XX International Workshop on Deep-Inelastic Scattering and Related Subjects
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Europe/Berlin
Wolfgang Paul Lecture Hall (University of Bonn)
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28,
53115 Bonn,
Germany,
Ian Brock
(Universitaet Bonn (DE))
Conference secretariat
Participants
300
View full list
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Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Ian Brock (Universitaet Bonn (DE))- 09:00
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Coffee break 30m Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany, -
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Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Aharon Levy (Unknown)- 11:00
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Lunch break 1h 30m Mensa Poppelsdorf
Mensa Poppelsdorf
University of Bonn
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Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Sven-Olaf Moch (Unknown)-
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Welcome 5mSpeaker: Ulf G. Meißner (University of Bonn)
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Coffee break 25m Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany, -
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Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Jochen Christian Dingfelder (Universitaet Bonn (DE))- 17:00
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Welcome reception 3h Mensa Poppelsdorf
Mensa Poppelsdorf
University of Bonn
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Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
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09:00
Combined inclusive diffractive cross sections measured with forward proton spectrometers at HERA 20mA combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses diffractive deep inelastic scattering data measured by means of proton spectrometers. Correlations of systematic uncertainties are taken into account by the combination method,resulting in improved precision. The combined data cover the range 2.5 < Q2 < 200 GeV2 in photon virtualities, 0.00035 < xIP < 0.09 in fractional momentum losses, 0.09 < |t| < 0.55 GeV2 in four momentum transfer at the proton vertex and 0.0018 < beta < 0.56 in beta = x/xIP, where x is the Bjorken scaling variable.Speaker: Valentina Sola (Universita e INFN (IT))
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09:20
Measurement of the Diffractive Longitudinal Structure Function F_L^D at HERA 20mFirst measurements are presented of the diffractive cross section $\sigma_{ep \rightarrow eXY}$ at centre-of-mass energies $\sqrt{s}$ of 225 and 252 GeV, together with a precise new measurement at $\sqrt{s}$ of 319 GeV, using data taken with the H1 detector in the years 2006 and 2007. Together with previous H1 data at $\sqrt{s}$ of 301 GeV, the measurements are used to extract the diffractive longitudinal structure function F_L^D in the range of photon virtualities 4.0 <= Q^2 <= 44.0 GeV^2 and fractional proton longitudinal momentum loss 5 10^{-4} <= x_{IP} <= 3 10^{-3}. The measured F_L^D is compared with leading twist predictions based on diffractive parton densities extracted in NLO QCD fits to previous measurements of diffractive Deep-Inelastic Scattering and with a model which additionally includes a higher twist contribution derived from a colour dipole approach. The ratio of the diffractive cross section induced by longitudinally polarised photons to that for transversely polarised photons is extracted and compared with the analogous quantity for inclusive Deep-Inelastic Scattering.Speaker: David Salek (CERN)
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Inclusive Measurement of Diffractive Deep Inelastic Scattering at HERA 20mMeasurements of the cross section for the diffractive process ep -> eXY are presented, where Y is a proton or a low mass proton excitation carrying a fraction 1 − xIP > 0.95 of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfying MY < 1.6 GeV and |t| < 1.0 GeV^2. Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range 3 <= Q2 < =1600 GeV^2, triple differentially in xIP , Q^2 and beta = x/xIP , where x is the Bjorken scaling variable. Thesemeasurements are made after selecting diffractive events by demanding that a large rapidity interval separates the final state hadronic systems X and Y . New measurements covering data taking periods 1999-2000 and 2004-2007 are combined with previously published results in order to provide a single set of diffractive cross sections using the large rapidity gap selection method from the H1 experiment. Comparisons of measurements with predictions from the diffractive parton density and dipole models are shown. Finally, the proton vertex factorisation hypothesis, which is an important aspect in the modelling of diffractive structure, is discussed.Speaker: Emmanuel Sauvan (LAPP (IN2P3/CNRS))
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Measurement of Dijet Production in Diffractive Deep-Inelastic Scattering with a Leading Proton at HERA 20mThe cross section of diffractive deep-inelastic scattering ep \rightarrow eXp is measured, where the system X contains at least two jets and the leading final state proton is detected in the H1 Forward Proton Spectrometer. The measurement is performed for fractional proton longitudinal momentum loss xIP < 0.1 and covers the range 0.1 < |t| < 0.7 GeV2 in squared four-momentum transfer at the proton vertex and 4 < Q2 < 110 GeV2 in photon virtuality. The differential cross sections extrapolated to |t| < 1 GeV2 are in agreement with next-toleading order QCD predictions based on diffractive parton distribution functions extracted from measurements of inclusive and dijet cross sections in diffractive deep-inelastic scattering. The data are also compared with leading order Monte Carlo models.Speaker: Richard Polifka (University of Toronto (CA))
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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Search for the Standard Model Higgs boson at ATLAS 24mThe experimental results of the search for the Standard Model Higgs boson at the Large Hadron Collider (LHC) running at a centre-of-mass energy of 7 TeV are reported, based on a total integrated luminosity of up to 4.9 fb-1 collected by the ATLAS detector in 2011. The search combines several Higgs boson decay channels in the mass range from 110 GeV to 600 GeV and derives upper limits on the production cross section as a function of the Higgs boson mass. A wide range of Higgs boson mass hypotheses is excluded at a 95% confidence level. Some excess of events is also reported.Speaker: Dr Prolay Kumar Mal (CEA - Centre d'Etudes de Saclay (FR))
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Status of SM Higgs searches at the Tevatron 24mWe present results from the search for a standard model Higgs boson using up to 10/fb of proton-antiproton collision data produced by the Fermilab Tevatron at a center-of-mass energy of 1.96 TeV. The data were recorded by the CDF and D0 Detectors between March 2001 and September of 2011. Updated results from many exclusive channels as well as the combined Tevatron search are presented.Speaker: Kyle Knoepfel (F)
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
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The LHCb upgrade 25mThe LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux of beauty and charmed hadrons produced at the LHC. The operation and the results obtained from the data collected in 2010 and 2011 demonstrate that the detector is robust and functioning very well. However, the limit of 1 fb$^{-1}$ of data per year cannot be overcome without improving the detector. We therefore plan for an upgraded spectrometer by 2018 with a 40 MHz readout and a much more flexible software-based triggering system that will increase the data rate as well as the efficiency specially in the hadronic channels. Here we present the LHCb detector upgrade plans, based on the recently submitted Letter of Intent, with a particular focus on prospects for QCD-related physics analyses.Speaker: Renaud Le Gac (Universite d'Aix - Marseille II (FR))
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
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Isolated photons+jet in DIS 20mIsolated-photon+jet production in ep collisions at a centre-of-mass energy of 318 GeV has been measured with the ZEUS detector at HERA using an integrated luminosity of up to 300 pb-1. Measurements of prompt-photon+jet cross sections are presented as functions of the photon transverse energy and pseudorapidity in a wide range of exchanged-photon virtuality. In addition, differential gamma+jet cross sections are presented as functions of the jet transverse energy and pseudorapidity. Leading-logarithm parton-shower Monte Carlo predictions and perturbative QCD calculations were compared to the data.Speaker: Oleg Kuprash (DESY)
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Photon Results from CDF 20mPrompt isolated photon pairs production cross sections, as well as direct photon production in association with a heavy (b or c) quark jets are presented. Differential cross sections are presented as a function of several variables. The results are compared with a next-to-leading order perturbative QCD calculations.
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Photon and photon+jet production measured with the ATLAS detector 20mIsolated prompt photons provide a direct probe of short-distance physics, complementary to that provided by measurements of jets or vector-bosons. The inclusive prompt photon cross section has been measured over a wide range of transverse momenta; the diphoton cross section has also been measured as a function of diphoton mass, total transverse momentum and azimuthal separation; the cross section for photons produced in association with jets is also measured. The results use data to suppress backgrounds, and also to remove the effects of underlying event and multiple proton-proton interactions in a theoretically well-controlled manner. The results are compared to the predictions of next-to-leading-order QCD.Speaker: Leonardo Carminati (Università degli Studi e INFN Milano (IT))
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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Inclusive D- and B-Meson Production at the LHC 18mI present predictions for the inclusive production of D- and B-mesons at the CERN LHC in the general-mass variable-flavor-number scheme at next-to-leading order, an approach which takes into account the finite mass of the heavy quarks. Numerical results are compared to data where available. Measurements at large rapidities have the potential to pin down models of intrinsic charm.Speaker: Hubert Spiesberger (Univ. Mainz)
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09:18
Heavy Flavour Production in ATLAS 18mATLAS has studied heavy flavour production in a variety of decay channels and inclusive signatures including charmed mesons, jets originating from b-quarks and inclusive muons and electrons. Differential production cross sections for beauty and charm are extracted from these signatures and compared with a variety of theoretical predictions.Speaker: Adam Edward Barton (Lancaster University (GB))
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Open heavy flavor production in pp collisions with ALICE at LHC 18mALICE is the LHC experiment dedicated to the study of the Quark Gluon Plasma (QGP) in Pb-Pb collisions. Heavy quarks are ideal probes to explore the QGP formation and properties, since they experience the full collision history and are expected to be abundantly produced at the LHC. It is of great importance to measure the heavy flavor cross section not only in Pb-Pb collisions, but also in pp collisions. In fact, the measurement in the latter is used both as a reference for the Pb-Pb results and as test of the pQCD predictions in a new energy domain. ALICE measures heavy quark production both at central and forward rapidity, reconstructing heavy flavour particles, both exclusively, using a selection of hadronic decay channels, and inclusively, using single leptons. Since the start up of the LHC, ALICE has been collecting Pb-Pb data at √sNN = 2.76 TeV and pp data at √s = 2.76 and 7 TeV. We present results on the measurement of heavy quark production through the hadronic decay channels of D mesons and via single leptons, with emphasis on the results obtained with pp data.Speaker: Rosa Romita (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))
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Production of c-cbar pairs at LHC: k_t-factorization and double-parton scattering 18mWe discuss charm production at LHC. The production of single $c \bar c$ pairs is calculated in the $k_t$-factorization approach. We use several unintegrated gluon distributions from the literature. Some of them include effect of small-$x$ saturation and fulfill Balitsky-Kovchegov evolution equation. The hadronization is included with the help of fragmentation functions found for the production of $c$ ($\bar c$) in $e^+ e^-$ collisions. Differential distributions for several charmed mesons will be presented and compared to recent results of the ALICE and LHCb collaborations. Some missing strength is identified. Different schemes of fragmentation are discussed. Furthermore we discuss production of two pairs of $c \bar c$ within a simple formalism of double-parton scattering (DPS). Surprisingly large cross sections, comparable to single-parton scattering (SPS) contribution, are predicted for LHC energies. Both total inclusive cross section as a function of energy and differential distributions are shown. We include recently discussed evolution of double partons in the case of two scales. We discuss perspectives how to identify the double scattering contribution. We find much larger cross section for large rapidity distance between charm quarks from different hard parton scatterings compared to single scattering. First predictions for two $c \bar c$ pair production in single-parton scattering will be presented. Predictions for the production of different pairs of charm mesons ($D0 $D0$, D0 {\bar D}0$, etc.) are presented for the kinematics of LHCb experiment. I will show also predictions for so-called nonphotonic electrons and muons coming from the semileptonic decays of charmed mesons. The double-parton scattering gives large contribution with large (pseudo)rapidity gap between electrons ($e^+ e^+, $e^- e^-, $e^+ e^-$) or muons. This can be measured experimentally.Speaker: Prof. Antoni Szczurek (Cracow, INP & Rzeszow Univ.)
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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Recent Results of Double Helicity Asymmetries at PHENIX 25mThe determination of the gluon polarization within the proton, $\Delta G$, is one of the critical pieces to understanding the proton spin puzzle. Using collisions of polarized protons with $\sqrt{s}=200 \:GeV$ and $\sqrt{s}=500 \:GeV$ at the Relativistic Heavy Ion Collider (RHIC), PHENIX can access gluons and $\Delta G$ at leading order. Constraints on $\Delta G$ come from measurements of double longitudinal asymmetries, $A_{LL}$, of various particle production cross sections. We will present the recent $A_{LL}$ results at central $(|{\eta}|<0.35)$ and forward $(3.1 < |{\eta}| < 3.9)$ rapidities along with comparisons to various models of the gluon polarization. A summary of the current issues limiting the precision of these measurements will follow. Finally, we will discuss the possibilities in the near to mid-term future of the PHENIX $\Delta G$ program, specifically, constraining $\Delta G$ at low-x.Speaker: Mr Scott Wolin (University of Illinois at Urbana-Champaign)
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New COMPASS Results on Polarized Parton Distributions Inside the Nucleon 25mA short review of the COMPASS results concerning gluon polarization inside the nucleon, DG/G, is given including two new measurements: Firstly, a DG/G determination in leading order and in three bin of the gluon momentum fraction x_g from asymmetries in high-p$_T$ hadron pair production for Q$^2>$1 (GeV/c)$^2$; secondly, a preliminary next-to-leading order analysis based on open charm production, i.e. D mesons decaying via various channels. The latter result is obtained from our combined proton and deuteron data. In addition the cross-section for the $D^*$ production is given and kinematic distribution of the $D^*$ are compared with the AROMA generator. Finally results for the LO flavor separation of the three lightest quark polarized parton distributions.Speaker: Marcin Stolarski (LIP Laboratorio de Instrumentacao e Fisica Experimental de Part)
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Structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
09:00
Measurement of high-Q2 e+p neutral current cross sections at HERA and determination of the structure function xF3 20mThe cross sections for neutral current deep inelastic scattering in e+p collisions with a longitudinally polarised positron beam have been measured using the ZEUS detector at HERA. The single-differential cross-sections dsigma/dQ2, dsigma/dx and dsigma/dy and the double-differential cross sections in Q2 and x are measured in the kinematic region Q2 > 185 GeV2 for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 136 pb-1 taken in 2006 and 2007 at a centre-of-mass energy of 318 GeV. The structure functions xF_3 and xF_3^{\gammaZ} are determined by combining the e+p results presented in this analysis with previously measured e-p neutral current data. The measured cross sections are compared to the predictions.Speaker: Friederike Januschek (DESY)
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Luminosity Measurement at HERA with Elastic QED Compton Events 20mAt HERA, deep inelastic scattering progresses have been studied in order to probe the fundamental forces predicted by the standard model and the structure of the proton. One of the most fundamental processes is the elastic production of photons, e p -> e p gamma. For the case where the momentum transfer at the proton vertex is small, but both the electron and the photon have significant transverse momentum, the process is referenced as elastic QED Compton scattering. This process has the feature that it may be calculated at high precision in the framework of perturbative QED, and experimental background from other processes, like deeply-virtual Compton scattering, is small. In this analysis, the rate of elastic QED Compton events together with the cross section predicted from QED in used to measure the integrated luminosity of H1 datasets. The results are compared to default measurements of the integrated luminosity using Bethe-Heitler events.Speaker: Stefan Schmitt (Ruprecht-Karls-Universitaet Heidelberg (DE))
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W,Z production at ATLAS, constraints on parton density functions and determination of the strange sea density 30mMerged abstract: "W/Z production at ATLAS, and constraints on parton density functions" "QCD analysis of the ATLAS W-> lnu and Z ->ll cross-sections measurements and determination of the strange sea density"Speaker: Uta Klein (University of Liverpool (GB))
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QCD NLO analysis of inclusive, charm and jet data (HERAPDF 1.7) 25mA preliminary global NLO QCD analysis of the HERA data is presented. The following data sets are used in this analysis: the NC and CC inclusive DIS cross sections obtained from the combination of the measurements from H1 and ZEUS based on HERA I and HERA II data at the nominal proton beam energy, the preliminary combined inclusive NC DIS cross sections at reduced proton beam energies,the inclusive jet cross sections from H1 and ZEUS and the preliminary combined HERA results on the structure function F2(charm).Speaker: Krzysztof Nowak (Deutsches Elektronen-Synchrotron (DE))
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Coffee break 20m
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Diffraction and vector mesons Lecture Hall, Institute for Applied Physcis
Lecture Hall, Institute for Applied Physcis
University of Bonn
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QCD fits in diffractive DIS revisited 20mA new method for the extraction of diffractive parton distributions is presented which avoids the use of Regge theory ansatz and is in much closer relation with the factorization theorem for diffractive hard processes.Speaker: Federico Alberto Ceccopieri (Fondazione Angelo Della Riccia Ente Morale)
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A global analysis of diffractive events at HERA 20mWe extract diffractive parton distribution functions (DPDFs) and diffractive structure functions from the most recent H1 and ZEUS diffractive DIS data obtained by various methods. We consider Pomeron as an object with parton distribution function, evolving according to the next-to-leading order (NLO) DGLAP equations within the framework of the ‘Fixed Flavour Number Scheme’ (FFNS). Having performed a global fit analysis, we achieve a very good description of all available measurements by introducing a new set of quark distribution form for the Pomeron. We predict longitudinal and charm proton diffractive structure function as well. Our results are compared with other analysis from the literature.Speaker: Mrs Sara Taheri Monfared (Semnan university and IPM)
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Evidence for breakdown of the DGLAP description in diffractive DIS at HERA 20mHERA data on diffractive DIS show deviations from twist 2 DGLAP predictions below Q^2 5 GeV^2 at low x_P, which may reach up to 100%. These deviations are consistent with higher twists effects extracted from the saturation model. It is a first direct evidence for the higher twists in DIS. This finding affects determination of the diffractive parton densities that are used for the predictions at the LHC.Speaker: Mariusz Sadzikowski (Jagiellonian University)
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Analysis of higher twists in DIS and diffractive DIS at HERA and its implications for the saturation model 20mWe present new results on determination of higher twist contributions in diffractive DIS and compare them to the inclusive DIS case. In both cases the framework for the estimates is provided by the saturation model. We discuss the methods of higher twist extraction from the saturation model and compare the results for DIS and DDIS. We point out a striking difference in higher twist importance between DIS and DDIS: at low Q2 the effects are minor in DIS and they are large in DDIS. Moreover a comparison to HERA data hints on a necessary improvement of higher twist treatment in the saturation model. We present a possible QCD explanation of both findings.Speaker: Leszek Motyka (Jagellonian Univerisity)
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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Searches for Beyond-Standard Model Higgs boson at ATLAS 18mThe discovery of a neutral Higgs boson with large decay branching fraction to tau and muon pairs, as well as the discovery of a charged Higgs boson would represent a strong evidence of new physics beyond the Standard Model. The experimental results of the searches for the Higgs bosons beyond the Standard Model with the ATLAS detector are reported. The searches are based on an integrated luminosity of up to 4.9 fb-1 of proton-proton collision data recorded at the Large Hadron Collider (LHC) at a centre-of-mass energy of 7 TeV. Exclusion limits on production cross-sections are given as function of the Higgs boson mass and are analyzed in the framework of the minimal supersymmetric model.Speaker: Bruno Lenzi (CERN)
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Searches for low-mass Higgs states at BABAR 18mSeveral types of new-physics models predict the existence of low-mass Higgs states. Previous BABAR searches for leptonic and invisible light-Higgs decays have excluded large regions of model parameter space. We present new searches for hadronic Higgs decays and for a dark-sector Higgs produced in association with a dark gauge boson.Speaker: Valentina Santoro (University of Ferrara)
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BSM Higgs and other bump searches at the Tevatron 18mIn Beyond Standard Model (BSM) theories such as supersymmetry, the electroweak symmetry breaking mechanism predicts one or several Higgs bosons with different couplings and masses compared to the Standard Model one. We will present the constraints on BSM theories coming from searches for exotic Higgs bosons from the CDF and D0 collaborations at the Tevatron. In addition, other bump searches will also be presented, such as in the dijet mass spectrum in W+2jets events.Speaker: Emilien Chapon (Centre d'Etudes de Saclay (CEN Saclay)-Unknown-Unknown)
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Future of DIS Seminar room, Bethe Centre for Theoretical Physcis
Seminar room, Bethe Centre for Theoretical Physcis
University of Bonn
- 11:00
- 11:25
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The E-906/SeaQuest experiment at Fermilab 25mThe E-906/SeaQuest experiment at Fermilab will continue a series of Drell-Yan measurements to explore the antiquark structure of the nucleon and nuclei. To extend existing measurements to larger values of Bjorken-x, a 120 GeV proton beam extracted from Fermilab's main injector is used, resulting in a factor of 50 more luminosity than previous experiments and enabling access to values of x up to 0.9. An overview will be presented of the key physics goals of the E-906/SeaQuest collaboration. These include investigation of the dramatic dbar/ubar flavor asymmetry in the nucleon sea and its behavior at high x; study of the EMC effect in Drell-Yan scattering and the unexpected absence of any antiquark excess in existing data; and measurements of the angular dependence of the Drell-Yan process, sensitive to spin-orbit correlations within the nucleon. The talk will conclude with a status report on the ongoing commissioning of this new experiment.Speaker: Dr Markus Diefenthaler (University of Illinois at Urbana-Champaign)
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Future Programme of COMPASS at CERN 25mCOMPASS at CERN is preparing for a new series of measurements on the nucleon structure comprising deep virtual Compton scattering and hard exclusive meson production using muon beams, as well as Drell-Yan reactions using a polarised proton target and a negative pion beam. The former will mainly constrain the generalized parton distribution H and determine the transverse size of the nucleon, while the later measurements will provide information on transverse-momentum dependent (TMD) PDFs. Of particular interest is to verify the predicted change of sign of T-odd TMD PDFs going from DIS to Drell-Yan reactions. The necessary hardware upgrades and the projected results of the programme will be discussed.Speaker: Dr Gerhard Mallot (CERN)
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
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11:00
Jet-veto efficiencies at all orders in QCD 20mWe present accurate (NLL+NNLO) predictions for jet-veto efficiencies for Higgs and Z production at the LHC, obtained with the automated resummation program CAESAR. We discuss all sources of theoretical uncertainties associated to the presented results, highlighting which further calculations would be needed in order to reduce them.Speaker: Andrea Banfi (Freiburg U)
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From Jet Counting to Jet Vetoes 20mThe properties of jets are used in many LHC physics searches. Higgs searches use jet vetoes and fixed recoil jet multiplicities. Searches for new physics particles require a careful distinction of decay jets from QCD jet radiation. We show that the exclusive number of jets at hadron colliders can be described with two simple patterns: staircase scaling and Poisson scaling. In photon plus jets production we can interpolate between the two patterns using simple kinematic cuts. The associated theoretical errors are well under control. We show how understanding the exclusive jet multiplicities significantly impacts Higgs searches and searches for supersymmetry at the LHC.Speaker: Peter Schichtel (ITP)
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11:40
Measurements of jet production in pp collisions with the ATLAS detector 20mDifferential jet cross sections and distributions have been measure inclusively, in dijet events and in multijet events, using information from the ATLAS calorimeters and tracking detectors. The inclusive jet measurements extend from 20 GeV to 1.5 TeV, and the dijet measurements cover a very wide mass range. Measurements based on tracking alone are sensitive only to the charged-particle content of the jet, but all accurate measurements down to low transverse momentum, where the onset of hard scattering can be studied as jets emerge from some scattering events. A wide range of QCD-based calculations is confronted with the data, ranging from soft physics models the high multiplicity partonic matrix elements and NLO QCD calculations matched to parton shower simulations, testing the understand of QCD in a new kinematic range.Speaker: Adam Yurkewicz (Northern Illinois University (US))
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The High-Energy-Jets framework applied to multi-jet production 20mThe theoretical description of multi-jet final states is an issue of great importance at the LHC. The High Energy Jets (HEJ) framework offers a new approach to this and provides an all-order resummation of the dominant contributions from wide-angle QCD radiation. I will give a brief introduction to the framework and then show comparisons to early data from ATLAS and CMS analyses and discuss comparisons with other theoretical frameworks. I will end by discussing current ongoing developments.Speaker: Jennifer Smillie
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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Constraining the intrinsic charm/bottom content of the nucleon via photon + heavy quark production 18mThe production of a prompt photon in association with a heavy-quark (charm or bottom) jet is a versatile process that can be used to study the structure of the proton and the nucleus. This process is extremely sensitive to the heavy quark PDFs, and can thus directly probe for intrinsic charm or bottom contributions. We present various predictions of this process at different colliders and detectors (D0,CDF, RHIC, ATLAS, CMS and LHCb) portraying how the different kinematic ranges affect the constraint of IC/IB.Speaker: Karol Kovarik (KIT)
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11:18
Fully massive scheme for jet production in DIS 18mWe present the consistent treatment of heavy quarks in jet production processes in DIS at NLO accuracy. The method is based on the ACOT massive factorization scheme (Aivazis-Collins-Olness-Tung) which is already in use in global fits for PDFs. Extension of this method to jets faces the problem of infra-red singularities, which have to cancel between real and virtual corrections. Moreover, potential mass singularities have to be controlled in both contributions. To this end, we extended the dipole subtraction method (S. Catani, S. Dittmaier, M. H. Seymour, Z. Trocsanyi), which in its original form did not take into account QCD massive splittings in the initial state. We constructed relevant kinematics and dipole splitting functions together with their integrals. We partially adapted the method in MC program and checked against the known massive inclusive NLO results.Speaker: Piotr Kotko
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Measurements with ATLAS detector of jets containing charm and bottom quarks 18mThe inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass, the azimuthal angle difference between the two jets, and the angular variable chi in two dijet mass regions. The results are compared to next-to-leading-order QCD predictions. D*+/- meson production in jets is also measured. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate.Speaker: David Calvet (Univ. Blaise Pascal Clermont-Fe. II (FR))
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Measurement of Inclusive D* Meson and D* Meson Dijet Cross Sections in Photoproduction at HERA 18mThe inclusive photoproduction of D* mesons and of D*-tagged dijets is investigated with the H1 detector at the $ep$ collider HERA. The kinematic region covers small photon virtualities $Q^{2} < 2\ {\rm GeV}^2$ and photon-proton centre-of-mass energies of $100 < W_{\gamma p} < 285\ {\rm GeV}$. Inclusive \dstar\ meson differential cross sections are measured for central rapidities $|\eta(D*)| < 1.5$ and transverse momenta $p_{T}(D*) >1.8\ {\rm GeV}$. The heavy quark production process is further investigated in events with at least two jets with transverse momentum $\ptj > 3.5\ {\rm GeV}$ each, one containing the \dstar\ meson. Differential cross sections for D*-tagged dijet production and for correlations between the jets are measured in the range $|\eta(D*)| < 1.5$ and $p_{T}(D*) >2.1\ {\rm GeV}$. The results are compared with predictions from Monte Carlo simulations and next-to-leading order perturbative QCD calculations.Speaker: Zlatka Georgieva Staykova (University of Antwerp (BE))
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12:12
Measurements of open heavy flavor production by PHENIX at RHIC 18mHeavy flavor quarks are produced in the early stages of heavy ion collisions and serve as an important probe of the strongly interacting deconfined medium believed to be produced in these collisions at RHIC. Measuring observables such as Nuclear Modification Factor and Elliptic Flow for open heavy flavor production can help in quantifying medium effects. Measurement of heavy flavor production in p+p collision is an absolutely necessary baseline measurement for nuclear modification factor. On the other hand, measurements of heavy quark production in p+p collisions provides an important cross-check of pQCD calculations. PHENIX has a unique ability to measure single lepton spectra both at |eta|< 0.35 and at 1.4<|eta|<1.9 rapidity ranges, with its Central and Muon arms, respectively. Single leptons are used to tag the production of heavy flavor quarks via semileptonic decay of heavy flavor mesons (D,B). The most recent PHENIX single lepton measurements for different colliding ion systems will be presented and compared to the most recent available theoretical model predictions.Speaker: Irakli Garishvili (Lawrence Livermore Nat. Laboratory (US))
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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11:00
TMD Theory Overview 35mTransverse momentum dependent (TMD) distribution and fragmentation functions are described as Fourier transforms of matrix elements containing non-local combinations of quark and gluon fields. While the collinear functions are light-cone correlators in which the non-locality is restricted along the light-cone, the transverse momentum dependent functions are light-front correlators including a transverse (space-like) separation away from the light-cone. In the matrix elements the time-ordering is superfluous and they are parts of the full (squared) amplitudes that account for the connections to the hadrons (soft parts). The collinear (x-dependent) parton (quark or gluon) distribution functions (PDF’s) that appear in the parameterization of collinear leading-twist correlators are interpreted as momentum densities including polarized parton densities in polarized hadrons. They involve only spin-spin densities and they do not allow for a description of single-spin asymmetries in high-energy scattering processes at leading 1/Q order in the hard scale Q. TMD (x and pT-dependent) PDF’s that appear in the parameterization of TMD correlators include spin-spin as well as momentum-spin correlations and they are able to describe single-spin and azimuthal asymmetries, such as Sivers and Collins effects in semi-inclusive deep inelastic scattering (SIDIS), but there are many open issues on pT-factorization. Upon taking moments in pT (or taking Bessel weights) the correlators involve higher-twist operators, but evaluated at zero-momentum (gluonic pole matrix elements). They can be incorporated in a ‘generalized’ factorization scheme with specific gluonic pole factors such as the sign in SIDIS versus Drell-Yan, which can be traced back to having TMD’s with non-trivial process-dependent past- or future-pointing gauge links appearing in the light-front separated, non-local operator combinations.Speaker: Piet J Mulders (VU University)
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11:35
One-Hadron transverse spin asymmetries at COMPASS 25mThe quark content of the nucleon at twist-two level in the collinear case can be fully characterized by three independent distribution functions for each quark flavour: the unpolarized distribution function f1(x), the helicity distribution function g1(x) and the transverse spin distribution function h1(x), also called transversity. The measurements of single spin asymmetries in semi-inclusive deep inelastic scattering (SIDIS) on a transversely polarized target are an important part of the COMPASS physics program. By measuring azimuthal asymmetries in hadron production one can access both transversity - using the Collins fragmentation function - and the Sivers distribution function. The COMPASS collaboration has measured these asymmetries in the scattering of a 160 GeV/c polarized mu+ beam off a transversely polarized 6LiD (deuteron) target in the years 2002-2004 and off a transversely polarized NH3 (proton) target in 2007 and 2010. In this contribution we present the results from the 2010 data for the Collins and Sivers asymmetries.Speaker: Christoph Adolph (Friedrich-Alexander-Univ. Erlangen (DE))
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12:00
Azimuthal distributions of charged hadrons, pions, and kaons produced in deep-inelastic scattering off unpolarized protons and deuterons 25mThe azimuthal $\cos\phi$ and $\cos2\phi$ modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measuread at the HERMES experiment. For the first time these modulations were determined in a four-dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.Speaker: Francesca Giordano (U)
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11:00
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Structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
11:00
Impact of LHC data on (NN)PDFs 25mA determination of parton distribution functions with reliable estimation of associated uncertainties is a key ingredient for exploiting the full physics potential of the experiments at the LHC collider. On the other hand, measurements from the LHC will provide important constraints on PDFs in kinematic regions which are so far not covered by data included in global analyses. In this talk I will discuss the effect of including recent LHC vector boson and inclusive jet production measurements into the NNPDF global parton fit. I will also show how the impact of including new data in a global fit can be rapidly assessed using a method based on Bayesian reweighting.Speaker: Dr maria ubiali (University of Edinburgh)
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11:25
ABM11 PDFs and benchmarks at NNLO 25mWe present a determination of the nucleon parton distribution functions (ABM11) and the strong coupling constant $\alpha_s$ at next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and fixed-target data for Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for $n_f=3,4,5$ and uses the \MSbar scheme for $\alpha_s$ and the heavy quark masses. The fit results are compared with other NNLO PDFs and used to compute the benchmark cross sections at hadron colliders to NNLO accuracy.Speaker: Sergey Alekhin
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11:50
Progress in the dynamical parton distributions 25mDifferent theoretical improvements and the inclusion of alternative data sets in the determination of dynamical parton distribution functions are reported. Highlights in the ongoing developments as well as the role of the input scale in parton analysis are discussed.Speaker: Pedro Jimenez-Delgado (Jefferson Lab)
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12:15
Uncertainties in Determining Parton Distributions at Large x: Results from the CJ Collaboration 20mThe results of a global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x, will be reported. Effects of target mass corrections (TMC), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. Importantly, uncertainties in parton distribution functions (PDFs) at large x arising from nuclear effects in deuterium F2 structure function data are evaluated. Within this global analysis, the impact on the PDFs from uncertainties in the deuteron wave function at short distances and nucleon off-shell effects, the use of relativistic kinematics, as well as the use of less a restrictive parametrization of the d/u ratio, have been assessed. In particular the d-quark and gluon PDFs are found to vary significantly with the choice of nuclear model. The impact of these uncertainties on the determination of the neutron structure function, and on W boson production and parton luminosity at the Tevatron and the LHC are highlighted. Prospects for new measurements sensitive to the d-quark and gluon distributions but insensitive to nuclear corrections will also be discussed.Speaker: Cynthia Keppel (Hampton University)
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12:35
An update on higher twist contributions to DIS structure functions 20mWe report on a QCD re-analysis of the unpolarized non-singlet world data data in the valence region up to $O(\alpha_s^{3(4)})$ correlated to the value of the strong coupling constant $\alpha_s(M_Z2)$ and the higher twist contributions. We investigate contributions of twist $\tau = 3$ and higher to the polarized structure functions $g_1(x,Q2)$ and $g_2(x,Q2)$.Speaker: Johannes Bluemlein (DESY)
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14:00
Lunch break 1h 5m Mensa Poppelsdorf
Mensa Poppelsdorf
University of Bonn
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16:05
Combined: Future of DIS/spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
- 14:00
- 14:25
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15:15
Generalized parton distributions from present and future measurements 25mWe discuss the access of generalized parton distributions (GPDs) from deeply virtual Compton scattering (DVCS) and deeply virtual meson production. We also illustrate that DVCS measurements at a future high-luminosity electron-ion-collider provide insight in both the transverse distribution of sea quarks and gluons as well as the proton spin decomposition.Speaker: Dieter Mueller (BNL and Ruhr-University Bochum)
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Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
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14:00
Central Exclusive Production in pp ̄ Collisions at CDF II 20mWe report central exclusive production results studied at the Run II Collider Detector at Fermilab with focus on our recently published paper on the first observation of exclusive γγ production in pp ̄ collisions at √s = 1.96 TeV at the Tevatron. In particular, starting from earlier studies by the CDF collaboration, we discuss exclusive dijet, dilepton, Z, J/Ψ and χc productions and finally our recent observation of exclusive diphoton production. Whereas the lepton pairs and Z are purely QED processes, the J/Ψ is produced by photo-production, mediated by photon-pomeron exchange (γ + IP). The double pomeron exchange producing the exclusive dijet, Charmonium and diphotons via quark-loop is of great interest looking towards the possibilities of finding an exclusive Higgs at the Large Hadron Collider (if it exists). The production mechanism for an exclusive Higgs is similar via a heavy quark-loop with no other particles produced.Speaker: Dr Erik Brücken (Helsinki Institute of Physics (FI))
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14:20
Exclusive dimuon production in the forward region with LHCb 20mWe report on studies of exclusive dimuon production, using LHCb experimental data. Exclusively produced muon pairs can be produced by two photon fusion (a QED process ideally suited to obtaining a precise integrated luminosity measure), or by resonance production. We show results for exclusive dimuon production, and observations of the exclusive J/psi. psi‘ and chi_c states, obtained with data at $\sqrt(s) = 7$~TeV. We compare our results to predictions.Speaker: Dermot Moran (Univ Manchester)
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14:40
Exclusive photon-photon processes in p-p collisions in CMS" 20mWe present the search for exclusive diphoton production and the measurement of exclusive dilepton production, based on the data recorded by the CMS experiment at the LHC in 2010. An upper limit on the cross section is set for exclusive diphoton production, which is compared with the QCD perturbative theory predictions using different PDF sets. The exclusive dielectron production provides an excellent control sample for exclusive diphoton production, and a comparison between the measurement and the QED prediction is discussed. In addition, we report a measured cross section of exclusive dimuon production, which is compared with the theoretical QED prediction evaluated with the event generator LPAIR."Speaker: Wenbo Li (Peking University (CN))
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15:00
News on Exclusive Production of the BSM Higgs Bosons 20mWe investigate the prospects for Central Exclusive Diffractive (CED) production of BSM Higgs bosons at the LHC using forward proton detectors installed at 220~m and 420~m distance around ATLAS and / or CMS. We update a previous analysis for the MSSM taking into account improvements in the theoretical calculations and the most recent exclusion bounds from the LHC. We extend the MSSM analysis to new benchmark scenarios that are in agreement with the cold dark matter relic abundance and other precision measurements. Finally, we comment on the determination of Higgs spin-parity and coupling structures at the LHC and show that the forward proton mode could provide crucial information on the $\cp$ properties of the Higgs bosons.Speaker: Dr Marek Tasevsky (Acad. of Sciences of the Czech Rep. (CZ))
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15:20
High energy exclusive leptoproduction of the rho-meson: theory and phenomenology 20mExclusive leptoproduction of vector mesons has been the subject of recent significant progress, both theoretically and experimentally. In particular, the hard regime with a highly virtual photon exchange allows to separate a short distance dominated amplitude of hard subprocess from suitably defined hadronic objects. However, a consistent picture is still missing, in particular for contributions to the scattering amplitude beyond the leading power in the photon virtuality. We recently described the hard production of transversally polarized rho-meson, up to twist 3 accuracy, including 2- and 3- particles Fock-states, in the HERA kinematics of high center-of-mass energy. Furthermore, we here show how saturation effects could be included in our model. This is based on the dipole representation of the scattering amplitude in coordinate space, which we extend up to twist 3, based on our previous studies of the scattering amplitude in momentum space. We compare our model with H1 and ZEUS data for the ratios of helicity amplitudes T(gamma*T -> rhoT )/T(gamma*L -> rhoL) and T(gamma*T -> rhoL)/T(gamma*L -> rhoL) and get a good description of the data.Speaker: Adrien Besse (L)
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15:40
W, Z and jet central exclusive production at the LHC 20mWe study the W/Z pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and W/Z bosons. Tagging the protons in the final state in the ATLAS Forward Physics detectors as an example allows to improve the reach on anomalous couplings by four orders of magnitude reaching the values predicted by extra-dimension theories. The measurement of the exclusive jet production using the same detectors at the LHC will also be described.Speaker: Emilien Chapon (Centre d'Etudes de Saclay (CEN Saclay)-Unknown-Unknown)
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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14:00
Some Z' and W' models facing current LHC searches 18mWe present the implications of recent LHC results on some classes of Z' and W' models. We also remark how the strongest bounds (coming for example from searches for Z' -> dileptons and W' -> lepton + neutrino) do not apply to some theoretically motivated resonances, and discuss where signals from such states would appear.Speaker: Ennio Salvioni (Universita e INFN (IT))
- 14:18
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14:36
Searches for new physics with leptons and/or jets at ATLAS 18mWe present the most recent results of searches beyond the Standard Model with leptons and /or jets conducted by the ATLAS collaboration based on several inverse femtobarns of data.Speaker: Antonio Policicchio (INFN Cosenza)
- 14:54
- 15:12
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Searches for fourth generation heavy quarks with the ATLAS detector 18mThe addition of one or more heavy quarks is a natural extension to the Standard Model. Fourth generation heavy quarks can be produced at the LHC at rates that can be observed in the 2011 data samples. The talk presents results from searches\'a0performed by the ATLAS collaboration for fourth generation quarks decaying via several potential decay channels.Speaker: Jiahang Zhong (University of Oxford (GB))
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
- 14:00
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14:20
Z+Jets results from CDF 20mInclusive Z boson plus jets cross sections, as well as bottom jet production in association with a Z-boson cross sections, are measured in a final state where the Z boson has decayed in two muons or electrons. Results are based on $\sim 9$ fb$ ^{-1}$ of data in $\rm p\bar{p}$ collisions at $\rm \sqrt{s}$ = 1.96 TeV collected with the CDF detector in Run II. Differential cross sections are measured as a function of several variables, among which jet transverse momentum, jet rapidity and jets multiplicity. Measurements are compared to results from different next-to-leading order perturbative QCD predictions and event generators.Speaker: Lorenzo Ortolan
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14:40
Studies of vector boson+jet production with ATLAS 20mThe production of jets in association with a W or Z boson in proton-proton collisions at 7 TeV is an important process to understand in QCD. The cross section, differential in several kinematics variables, has been measured up to high jet multiplicities and compared to new higher-order QCD calculations. The ratio of (Z + a single jet)/(W + a single jet) can provide a very precise test of QCD and has also been measured. In addition, the cross sections for vector bosons produced with bottom jets, Z+b-jet and W+b-jet, have been measured and compared to NLO QCD calculations. Overall, the cross sections demonstrate the need for the inclusion of higher-multiplicity matrix elements in the calculations, even in cases where a parton shower simulation is present.Speaker: Camille Belanger-Champagne (McGill University (CA))
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15:00
W+n-jet predictions at NLO matched with a parton shower 20mThe MC@NLO method as implemented in the Sherpa MC generator is presented using the production of W-bosons in conjunction with up to three jets as an example. Corresponding results computed at next-to leading order in QCD and including parton shower corrections are compared to recent experimental data from the Large Hadron Collider.Speaker: Frank Siegert (Albert-Ludwigs-Universitaet Freiburg (DE))
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15:20
Matching Tree-Level Matrix Elements with Interleaved Showers 20mWe present the recent implementation of CKKW-L merging inside Pythia8, and comment on the treatment of multiparton interactions in the context of matrix element merging. Since multiple interactions inside Pythia8 are fully interleaved with space- and time-like showers, care has to be taken when allowing for MPI. Further, we will discuss the uncertainties of the implementation.Speaker: Stefan Prestel (L)
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15:40
Subleading N-colour improved Parton Showers 20mParton shower Monte Carlos are by now standard tools to simulate hadronic final states. Having seen a tremendous improvement of combining parton showers and fixed order calculations in recent years, efforts are now underway to improve the shower approximations themselves, as well. In this contribution we will present first steps towards including subleading colour contributions into parton shower algorithms and discuss the impact of these corrections. Technical aspects required to arrive at such an improved algorithm, particularly generalizations of the Sudakov veto algorithm, will also be discussed.Speaker: Simon Plaetzer (DESY Hamburg)
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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14:00
Charm fragmentation fractions in Photoproduction 18mThe production of D*, D+, D0, Ds and Lambda_c charm hadrons and their antiparticles in ep scattering at HERA was studied with the ZEUS detector using the full HERA II data set. The measurement has been performed in the photoproduction regime. The fractions of c quarks hadronising as a particular charm hadron, f(c -> D, Lambda_c), were derived in the visible kinematic range. The obtained fractions can be compared to previous results from HERA and to measurements from e+e- experiments.Speaker: Ganna Dolinska (Kiev University)
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14:18
Soft-gluon resummation in heavy top-pair production at hadron colliders 18mThe current state of the art in top-pair production is based on threshold resummation on top of the exact NLO result. We will examine the role - and the limitations - of the soft-gluon approximation in describing precision top-pair production at hadron colliders. We will demonstrate that the only way to substantially improve our knowledge of this observable is through fixed order calculation at NNLO. The status of this ongoing calculation will also be presented.Speaker: Alexander Mitov (CERN)
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14:36
Differential and total cross sections for top pair and single top production 18mI present theoretical results at approximate NNLO for top quark production at the LHC at 7 and 8 TeV energy. Total cross sections are shown for ttbar production and single top production in the t and s channels and via associated tW production.Top quark transverse momentum and rapidity distributions are also presented.Speaker: Nikolaos Kidonakis (Kennesaw State University)
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14:54
ATLAS: Top quark pair production cross-section 18mWe present measurements of the production of top quarks in proton-proton collisions at 7 TeV with the ATLAS detector at the Large Hadron Collider. The cross section of pair-produced top quarks is measured in several channels, including the single lepton, dilepton and all hadronic channel, some using information from b-tagging.Speaker: Kate Shaw (Abdus Salam Int. Cent. Theor. Phys. (IT))
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15:12
CMS: Measurements of total and differential top-production cross sections 18mWe present precise measurements of the top quark pair production cross section at 7 TeV, performed using CMS data collected in 2010-2011. The total cross section is measured in the lepton+jets, dilepton and fully hadronic channels, including the tau-dilepton and tau+jets modes. The results are combined and confronted with precise theory calculations. We also obtain an indirect constraint on the top quark mass through its relation to the cross section. Various differential cross sections are measured as well and compared with theoretical models. Measurements of the top pair invariant mass distribution are used to search for new particles decaying to top pairs. Further results include measurements of the top pair charge asymmetry and single top production.Speaker: Antonio Tropiano (Universita e INFN (IT))
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15:30
Top quark production at D0 18mWe present measurements of the cross sections for the production of top-antitop quark pair production via the strong interaction and for the production of single top quarks via the weak interaction in proton-antiproton collisions at sqrt(s)=1.96 TeV using data corresponding to integrated luminosities of up to 5.4 fb-1. The data were collected with the D0 detector at the Fermilab Tevatron collider. For the top-antitop pair production, measurements are obtained from the study of the kinematic properties and of the b-tagging rates in final states for with either a charged lepton pair accompanied by additional jets and missing transverse momentum, and in final states with one charged lepton, three or more jets and missing transverse momentum. For the single top quark production the measurement is obtained from the final states with one charged lepton, at least two jets and missing transverse momentum, and studies of the relative contributions of different production mechanisms are also presented. Finally we present measurements of the forward-backward asymmetry in the top-antitop quark final states.Speaker: Karel Soustruznik (C)
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15:48
Top quark physics in CDF 18mThe study of the dynamics of top-quark pair production in proton-proton and proton-antiproton collisions plays an important role in the understanding of parton interactions at large Bjorken-x. It tests the assumptions of the standard model and of quantum chromodynamics at the electroweak scale and beyond. The CDF data set is an ideal sample for measuring observables sensitive to the dynamics of top-quark pair production, given the excellent understanding of detector performance and the unique proton-antiproton initial state. We present recent measurements of such observables from CDF. These include the direct measurement of the ratio R of the branching fraction of top-quark decaying to W + b-quark over the branching fraction of top-quark decaying to W + any quark flavor. The measurement uses data corresponding to 7.5/fb of integrated luminosity in the lepton+jets decay channel. The ratio R constrains the |V_tb| element of the CKM matrix. We also present a measurement of the spin correlation coefficient of the top-quark pair, which can be directly measured uniquely in the top-pair system thanks to the very short life time of the top-quark. This measurement uses data corresponding to 5.1/fb of integrated luminosity in the dilepton decay channel. Finally, we present a study of the top-quark pair production asymmetries in the lepton+jets channel using the full CDF Run II data set which corresponds to an integrated luminosity of 8.7/fb. The study includes the measurement of the cross section differential in the top-pair rapidity difference, the measurement of the inclusive forward-backward asymmetry A_FB, as well as the measurement of A_FB as a function of the rapidity difference and of the invariant mass of the top-pair system. The production asymmetries are sensitive to the top-quark pair production mechanism, thus constraining quantum chromodynamics at higher order and testing for possible new physics.Speaker: Konstantinos Vellidis (University of Athens (GR))
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Structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
14:00
Progress in CTEQ-TEA PDF analysis 25mI discuss latest developments in the CTEQ-TEA PDF analysis: NNLO PDFs, benchmarking of NLO and NNLO cross sections included in the global fits, analysis of constraints on PDFs with the method of PDF-induced correlations.Speaker: Pavel Nadolsky (Southern Methodist University)
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14:25
Global Analysis of Nuclear Parton Distributions 20mWe present a new global QCD analysis of nuclear parton distribution functions and their uncertainties. In addition to the most commonly analyzed data sets for deep inelastic scattering of charged leptons off nuclei and Drell-Yan di-lepton production, we include also measurements for neutrino nuclei scattering as well as inclusive pion production in deuteron gold collisions. The analysis is performed at next-to-leading order accuracy in perturbative QCD in a general mass variable flavor number scheme, adopting a current set of free nucleon parton distribution functions, defined accordingly, as reference. The emerging picture is one of consistency, where universal nuclear modification factors for each parton flavor reproduce the main features of all data without any significant tension among the different sets. We use the Hessian method to estimate the uncertainties of the obtained nuclear modification factors and examine critically their range of validity in view of the sparse kinematic coverage of the present data. We briefly present several applications of our nuclear parton densities in hard nuclear reactions at BNL-RHIC, CERN-LHC, and a future electron ion collider.Speaker: Rodolfo Sassot (Universidad de Buenos Aires)
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14:45
An update and comparison of global NPDF analyses 20mA global NPDF analysis of the combined charged-lepton DIS, DY and neutrino DIS data finds a tension between the nuclear correction factors in nA DIS and ℓA DIS. We explore possible sources of this tension by comparing the input PDFs used by different nuclear global fitting groups, and also compute ratios of experimental observables which (largely) minimize any theoretical bias. We also show comparisons with recent nPDF determinations. This work helps to isolate the sources of possible tensions in the extracted nuclear corrections.Speaker: Karol Kovarik (University of Karlsruhe)
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15:05
Using the BFKL resummation to fit DIS data: collinear and running coupling effects 20mThe proton structure function F_2 is studied in the low x regime using BFKL evolution instead of the usual DGLAP approach, suited for large values of the DIS x variable. The NLL analysis requires the inclusion of running coupling effects which lead to off-diagonal terms in the BFKL kernel that need to be treated carefully. We also introduce an all-orders resummation that improves the collinear behavior of the NLL BFKL result. This study is presented emphasizing the theoretical uncertainties that appear throughout the analysis and a comparison with the combined HERA data is given.Speaker: Clara Salas (IFT, Madrid)
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Determination of CCFM uPDF with combined HERA data 20mWe present a new determination of the un-integrated PDF using the combined HERA data. We obtain acceptable chi*2/ndf. We find that for a good description of HERA data the gluon splitting function including non-singular terms as well as kinematic constraints and NLO alphas are necessary. We determine for the first time a full set of uncertainty uPDFs which allow to study the uPDF uncertainty for processes at HERA and the LHC. We also show a comparison of predictions using the new uPDFs with measurements from HERA and the LHC.Speaker: Hannes Jung (Deutsches Elektronen-Synchrotron (DE))
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Coffee break 20m
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18:00
Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
- 16:50
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17:10
Probing the Low-x Structure of the Nucleus with the PHENIX Detector 20mOne of the fundamental goals of the PHENIX experiment is to understand the structure of cold nuclear matter, since this serves as the initial state for heavy-ion collisions. Knowing the initial state is vital for interpreting measurements from heavy-ion collisions. Moreover, the structure of the cold nucleus by itself is interesting since it is a test-bed for our understanding of QCD. In particular there is the possibility of novel QCD effects such as gluon saturation at low-x in the nucleus. At RHIC we can probe the structure of cold nuclear matter using d+Au collisions. We will present measurements of forward di-hadron correlations and inclusive J/Psi production, which seem to show some interesting effects in the cold nucleus, especially as one probes down to Bjorken x of about $10^{-3}$ in the Au nucleus.Speaker: Dr Mickey Chiu (Brookhaven National Lab)
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17:30
Diffractive pQCD mechanisms of exclusive production of $b \bar b$ dijets and $W^+ W^-$ pairs in proton-proton collisions 20mWe discuss central exclusive production of $W^+W^-$ pairs in proton-proton collisions at LHC. Several observables related to this process are calculated. Predictions for the total cross section and differential distributions in rapidity and transverse momentum of $W^{\pm}$ and $WW$ invariant mass are presented. We show results for different polarization states of the final $W^{\pm}$ bosons. We discuss both $\gamma \gamma \to W^+ W^-$ mechanism as well as a new mechanism of exclusive diffractive production. The amplitude for the latter process is calculated in the Durham model used recently to estimate cross section for exclusive production of Higgs boson, gluon-gluon, $b \bar b$ dijets as well as for pairs of photons. Some results for those processes will be discussed briefly and compared to the CDF collaboration data. The amplitude for the $p p \to p p W^+ W^-$ process is expressed in terms of off-diagonal unintegrated gluon distribution functions. We compare the two (QED and QCD) types of contributions. The phase space integrated diffractive contribution when separated is only a small fraction of fb compared to 115.4 fb of the $\gamma \gamma$ contribution. The $\gamma \gamma$ contribution dominates at small four-momentum transfers squared in the proton lines as well as in a broad range of $W^+ W^-$ invariant masses. This opens a possibility of searches for anomalous four-boson $\gamma \gamma W^+ W^-$ coupling due to new physics beyond Standard Model. The example are Higgsless models. The presentation will be based mostly on our recent study. I will also show some published results on exclusive production of Higgs and dijets.Speaker: Prof. Antoni Szczurek (Institute of Nuclear Physics Krakow (Poland))
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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16:30
Measurement of the neutrino velocity with the OPERA detector in the CNGS beam 18mThe OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies.Speaker: Torben Ferber (Hamburg University)
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A theoretical review of the implications of recent OPERA results 18mWe review the theoretical implications of the OPERA results, with particular emphasis on the consistency with other tests of special relativity (directly or through quantum effects in the charged lepton sector) and the difficulties in construction of models satisfying all constraints.Speaker: Sergey Sibiryakov (Institute for Nuclear Research of RAS)
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Results from NA48 and NA62 18mMerged abstract: "High precision measurement of the form factors of the semileptonic decays K+- -> pi0 l+- nu (Kl3)" "Rare kaon decay measurements with NA62 minimum bias data." "First Measurement of the very rare Decay K+ -> pi+ pi0 e+ e-" "Lepton Universality Tests in Kaon Decays at NA62"Speaker: Mauro Piccini (Universita e INFN (IT))
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
- 16:30
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The CLAS12 Physics Program 25mWith the doubling of the Jefferson Lab beam energy and the complete rebuilding of the CLAS spectrometer underway, a full experimental program is already approved for Hall B. The components of this program relevant to deep-inelastic scattering will be discussed.Speaker: Keith Griffioen (C)
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17:20
Precision Polarized SIDIS Experiments in Hall-A at 12 GeV JLab 25mOne of the cleanest ways to access the Transverse Momentum Dependent (TMD) parton distribution functions of the nucleon is to measure single (SSA) and double spin asymmetries (DSA) in semi-inclusive DIS reactions using polarized nucleon targets. The Jefferson Lab 12 GeV upgrade will provide a unique opportunity to perform such precision measurements and to map these multi-dimensional PDFs. In this talk, we will present our plans for performing these precision measurements in Hall-A using Large acceptance SoLID spectrometer and polarized proton and 3 He (neutron) targets. In particular, we will focus on two approved A-rated experiments using both longitudinally and transversely polarized 3 He targets, and a conditionally approved experiment with a transversely polarized proton target. The high luminosities from these targets and the large acceptance of the SoLID spectrometer will allow for a precise 4-dimensional (x, Q2 , z, PT ) mapping of SSA and DSA. The full azimuthal angular coverage is necessary to untangle various angular moments and thereby reduce the systematic uncertainties. These experiments will provide the most precise data to extract transversity, Sivers and Worm-gear distributions of u and d-quarks and provide comprehensive information on the correlation between quark angular momentum and the nucleon’s spin.Speaker: Mr Kalyan Allada (Jefferson Lab)
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
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16:30
Towards parton shower to 2 to 2 matrix element matching in kt-factorisation 20mWe present a subtraction method for including next to leading order corrections to a 2 to 2 jet production process in kt-factorisation equivalent to a jet matching procedure in Monte Carlo generators. We study the improvement in soft cut dependance.Speaker: Dr Michal Deak (Universidade de Santiago de Compostela)
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16:50
Drell-Yan lepton pair production in the kt-factorization approach 20mIn the framework of the kt-factorization approach, the production of unpolarized Drell-Yan lepton pair at high energies is studied. The consideration is based on the O(alpha) and $O(alpha alpha_s) off-shell partonic matrix elements with virtual photon and Z boson exchange. The calculations include leptonic decays of Z bosons with full spin correlations as well as gamma - Z interference. The unintegrated parton densities in a proton are determined by the Kimber-Martin-Ryskin prescription. Our numerical predictions are compared with the data taken by the D0, CDF and CMS collaborations at the Tevatron and LHC energies. Special attention is put on the specific angular distributions measured very recently by the CDF collaboration for the first time.Speaker: Mr Maxim Malyshev (SINP MSU)
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17:10
Electroweak Gauge-Boson and Higgs Production at Small qT : Infrared Safety from the Collinear Anomaly 20mWe discuss the differential cross sections for electroweak gauge-boson and Higgs production at small and very small transverse momentum q_T. Large logarithms are resummed using soft-collinear effective theory. The collinear anomaly generates a non-perturbative scale q^∗, which protects the processes from receiving large long-distance hadronic contributions. A numerical comparison of our predictions with data on the transverse-momentum distribution in Z-boson production at the Tevatron and LHC is given.Speaker: Daniel Wilhelm (Mainz U)
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17:30
Quark and Gluon Tagging at the LHC 20mDistinguishing light-quark jets from gluon jets on an event-by-event basis could significantly enhance the reach for many new physics searches at the Large Hadron Collider. Through an exhaustive search of existing and novel jet substructure observables, we find that a multivariate approach can filter out over 95% of the gluon jets while keeping more than half of the light-quark jets. Moreover, a combination of two simple variables, the charge track multiplicity and the p_T-weighted linear radial moment (girth), can achieve similar results. I will discuss applications and address theoretical issues in the definitions of quark and gluon jets.Speaker: Jason Gallicchio (UC Davis)
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17:50
Normalised Multi-jet Cross Sections using Regularised Unfolding and Extractions of alpha_s(M_Z) in Deep-Inelastic Scattering at high Q^2 at HERA (H1) 20mNew results on normalised inclusive jet, di-jet and trijet differential cross sections in neutral current deep-inelastic ep scattering (DIS) based on a regularised unfolding procedure are presented. Detector effects like acceptance and migrations as well as statistical correlations between the multi-jets and the inclusive DIS events are taken into account in this procedure. The DIS phase space of this measurement with the H1 detector is given by the virtuality of the exchanged boson (gamma*,Z^0) 150 < Q^2 < 15000 GeV^2 and the inelasticity of the interaction 0.2 < y < 0.7. The jets are reconstructed in the Breit frame of reference using the k_t jet algorithm. In all cases the jet pseudorapidities in the laboratory frame are required to be in the range -1.0 < eta_lab < 2.5. For inclusive jets the transverse momenta in the Breit frame are 7 < P_T < 50 GeV. The di-jet and tri-jet phase space are defined by requiring 5 < P_T,i < 50 GeV, and the invariant mass of the two leading jets M_1,2 > 16 GeV. Compared to a previously published result on normalised multi-jet cross sections, the new features are an extended range in jet pseudorapidity, an improved hadronic energy scale uncertainty of 1% and the adoption of a regularised unfolding procedure. The unfolded normalised jet cross sections are compared to QCD calculations at NLO and values for the strong coupling alpha_s(M_Z) are extracted.Speaker: Daniel Andreas Britzger (Ludwig-Maximilians-Universitat Munchen)
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Inclusive-Jet Photoproduction at HERA 20mDifferential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q2 < 1 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb-1. Jets were identified in the laboratory using the kt cluster algorithm in the longitudinally inclusive mode. Cross sections are presented as functions of the jet pseudorapidity, etajet,and the jet transverse energy, Etjet. In addition, measurements of double-differential inclusive-jet cross sections are presented as functions of Etjet in different regions of etajet. These cross sections have the potential to constrain the gluon density in the proton and the photon when included as input to fits to extract the proton parton distribution functions. Next-to-leading-order QCD calculations give a good description of the measurements. A value of alphas(Mz) has been extracted from the measurements. The energy-scale dependence of the coupling has also been determined.Speaker: ewald paul (P)
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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16:30
ATLAS top quark mass measurement 18mWe present a measurement of the top-quark mass in proton-proton collisions at 7 TeV with the ATLAS detector at the Large Hadron Collider. The top mass is determined by making use of a two-dimensional template method in the single lepton channel. An indirect extraction of the top-quark mass from the measurement of the cross-section is also presented.Speakers: Christian Andreas Jung (TU Dortmund), Christian Andreas Jung (Technische Universitaet Dortmund (DE))
- 16:48
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Top-quark pair-production with one jet and parton showering at hadron colliders 18mWe discuss heavy-flavor production in association with one jet hadronic collisions matched to parton shower Monte Carlo programs at next-to-leading order QCD with account of top-quark decays and spin correlations in the decay products. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. Phenomenological studies for the LHC and the Tevatron are presented. In particular we study the impact of the parton shower on the top-quark charge asymmetry.Speaker: Sven-Olaf Moch (Unknown)
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17:42
Top--antitop quark + X hadroproduction at NLO accuracy with decay and evolution to the hadron level 18mAiming at better understanding of the properties of top quarks, we focus on top--antitop+X production at the LHC, with X being a vector, or scalar/pseudoscalar boson. We show predictions obtained by PowHel, a computing framework based upon the POWHEG-BOX program with input obtained from HELAC-NLO. The POWHEG-BOX generates event files according to the Les-Houches accord, and uses the POWHEG matching formalism to further evolve these events to the hadron level ready for use in any experimental analysis. We discuss the sensitivities of our predictions to the choice of the Shower Monte Carlo code (PYTHIA vs. HERWIG). We show examples of how the choice of different experimental cuts and/or heavy particle reconstruction strategies can affect the predictions and help disentangle our signals from important backgrounds, also involving top-quark production and decay.Speaker: Adam Kardos (University of Debrecen)
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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Recent STAR results and future prospects of the W boson program at RHIC at BNL 30mThe STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions at $\sqrt{s}=200\,$GeV and $\sqrt{s}=500\,$GeV to gain a deeper insight into the spin structure and dynamics of the proton. The completion of the first $\sqrt{s}=500\,$GeV polarized proton run in 2009 opened a new era of spin-flavor structure measurements from $W^{-(+)}$ boson production. $W^{-(+)}$ bosons are produced in $\bar{u}+d\,(\bar{d}+u)$ collisions and can be detected through their leptonic decays, $e^{-}+\bar{\nu}_{e}\;(e^{+}+\nu_{e})$, where only the respective charged lepton is measured. The discrimination of $\bar{u}+d\;(\bar{d}+u)$ quark combinations requires distinguishing between high $p_{T}$ $e^{-(+)}$ through their opposite charge sign, which in turn requires precise tracking information. Recent published STAR results on the first measurement of $W^{-}/W^{+}$ and $Z$ boson production will be shown. The STAR experiment has recently started the installation of the Forward GEM Tracker to enhance the charge separation of high $p_{T}$ $e^{-(+)}$ at forward pseudorapidities and will begin the commissioning of this new tracking system during the upcoming 2012 running period. The status of the Forward GEM Tracker along with a discussion of future prospects will be presented.Speaker: Prof. Bernd Surrow (MIT)
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17:00
NNPDF determination of polarized parton distributions of the nucleon at NLO 20mWe present a preliminary determination of a set of polarized parton distributions of the nucleon, at next-to-leading order, from a global set of deep-inelastic scattering data. The determination is based on the NNPDF methodology: a Monte Carlo sampling with neural networks used as unbiased interpolants. This method, which has already been applied to a determination of unpolarized parton distributions, is designed to provide a faithful and statistically sound representation of the uncertainty on parton distributions. We discuss the general NNPDF procedure to parton fitting, focusing on the algorithm used to determine the optimal fit. We also present a preliminary set of polarized PDFs, compared to other parton extractions recently obtained by other collaborations. In particular, we show that "traditional" fits tend to underestimate the PDF uncertainty, particularly for the gluon, which is basically unconstrained by inclusive DIS data.Speaker: Emanuele Roberto Nocera (Universita degli Studi di Milano and INFN, Milano)
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17:20
Longitudinal semi-inclusive double-spin asymmetries at HERMES. 20mFinal measurements are reported on the double-spin asymmetries for a longitudinally polarized hydrogen and deuterium targets at HERMES using the27.6 GeV HERA lepton beam. The kinematic dependences of the longitudinal semi-inclusive asymmetry simultaneously on Bjorken-x and hadron transverse momentum p_h, and Bjorken-x and the hadron energy fraction z are explored. Additionally, the hadron charge-difference asymmetry is presented, which under certain model assumptions grants access to the parton distributions of the valence quarks.Speaker: Dr Polina Kravchenko (DESY)
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$W$ Physics in Polarized Proton-Proton Collisions at PHENIX 20mA major direction of the physics program at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is to explore the origin of proton spin structure. Parity violating single spin asymmetries, $A_L$, for $W$-bosons in longitudinally polarized $p + p$ collisions at a center of mass energy of $\sqrt{s}$ = 500 GeV will give access to the flavor separated quark and anti-quark polarization distributions for up- and down-quarks in the proton. The PHENIX collaboration has measured $A_L$ for electrons from $W$-decay in the central rapidity region, $-0.35 < \eta < 0.35$ based on a data sample taken in 2009. A second data sample taken in 2011 is being used to measure $A_L$ for $W$-decays into muons with two PHENIX forward muon spectrometers covering $1.2 < |\eta| < 2.4$. Cross sections for $W^\pm$-boson production at central rapidity and the corresponding single spin asymmetries will be presented. The cross sections will be compared with similar measurements at LHC. The upgrade effort directed at $W$-physics in the muon spectrometers just has been completed. The new instrumentation will be briefly described and the the status of the $W$-analysis in the PHENIX muon spectrometers will be discussed.Speaker: Young Jin Kim (University of Illinois at Urbana-Champaign)
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Structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
16:30
Photon impact factor for BFKL pomeron at next-to-leading order 15mI will present an analytic expression in momentum space of the next-to-leading order photon impact factor for small-x deep inelastic scattering. The result is calculated using the operator product expansion in Wilson lines.Speaker: Giovanni Antonio Chirilli (Lawrence Berkeley National Laboratory (LBNL))
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Low x physics: a critical phenomenon? 15mThe DIS structure functions are expressed, in a rigorous way, as correlation functions in a quantum field theory containing a parameter r. It is shown that low x physics corresponds to the theory in the limit of r going to zero where the theory develops a large correlation length. This indicates critical behaviour. The data on F2 are analysed in a geometric way and values for the critical indices are extracted.Speaker: Prof. Otto Nachtmann (Institute for Theoretical Physics, University of Heidelberg)
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The Recent F_L Measurement from HERA and the Dipole Model 20mFrom the new measurement of F_L at HERA we derive fixed-Q^2 averages <F_L/F_2>. We compare these with bounds which are rigorous in the framework of the standard dipole picture. The bounds are sharpened by including information on the charm structure function F_2^(c). Within the experimental errors the bounds are respected by the data. But for 3.5 GeV^2 <= Q^2 <= 20 GeV^2 the central values of the data are close to and in some cases even above the bounds. Data on F_L/F_2 significantly exceeding the bounds would rule out the standard dipole picture at these kinematic points. We discuss, furthermore, what can be learned from data respecting the bounds but coming close to them.Speaker: Carlo Ewerz (ExtreMe Matter Institute EMMI, GSI, and Heidelberg University)
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17:20
Nonlinear equation for coherent gluon emissions 15mMotivated by the explored nowadays at LHC the regime of QCD where both the total energy of collision and momenta transfers are high, we investigate evolution equations of high energy factorization. In order to study such effects like parton saturation in final states one is inevitably lead to investigate how to combine physics of the BK and CCFM evolution equations. In this letter we obtain a new exclusive form of the BK equation which suggests a possible form of the nonlinear extension of the CCFM equation.Speaker: Krzysztof Kutak (I)
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17:35
The statistical model for parton distributions 20mFirst we recall the basic physical features of the parton distribution functions (PDF) in the quantum statistical approach of the nucleon. Several predictions from next-to-leading QCD calculations using these PDF are compared with recent experimental results: deep inelastic scattering from HERA, hadronic reactions from Tevatron and RHIC, neutrino data and also polarized data obtained by Compass at CERN and by the polarized pp collider at BNL.Speaker: Franco Buccella (Unknown)
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Combined: Hadronic final states/diffraction and vector mesons Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
- 08:30
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08:50
Measurement of Photon Production in the Very Forward Direction in Deep-Inelastic Scattering at HERA [H1] 20mThe production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron-proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of $126 \mathrm{pb}^{-1}$. The analysis covers the range of negative four momentum transfer squared at the positron vertex $6<Q^2<100$ GeV$^2$ and inelasticity $0.05<y<0.6$. Cross sections are measured for the most energetic photon with pseudorapidity $\eta>7.9$ as a function of its transverse momentum $p_T^{lead}$ and longitudinal momentum fraction of the incoming proton $x_L^{lead}$. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction $x_L^{sum}$ of all photons in the pseudorapidity range $\eta>7.9$. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays.Speaker: Hamlet Zohrabian
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09:10
Measurement of the Azimuthal Correlation between the most Forward Jet and the Scattered Positron in Deep-Inelastic Scattering at HERA [H1] 20mDeep-inelastic positron-proton scattering events at low photon virtuality Q^2 with a forward jet, produced at small angles with respect to the proton beam, are measured with the H1 detector at HERA. A subsample of events with an additional jet in the central region is also studied. For both samples differential cross sections and normalised distributions are measured as a function of the azimuthal angle difference, Delta phi, between the forward jet and the scattered positron. The sensitivity to QCD evolution mechanisms is tested by comparing the data to predictions of Monte Carlo generators based on different evolution approaches as well as to next-to-leading order calculations.Speaker: Lidia Goerlich (High Energy Department-Henryk Niewodniczanski Inst. Nucl. Physic)
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09:30
Forward Jets and Small-x Physics at the LHC 20mWe discuss QCD aspects of forward jet hadroproduction, including issues on factorization at large rapidities; shower Monte Carlo implementations; the role of forward jet and energy flow measurements at the LHC to investigate contributions to parton showers from large-angle gluon radiation and from multiple parton interactions.Speaker: Francesco Hautmann (University of Oxford (GB))
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09:50
Probing colour flow with jet vetoes 20mI discuss jet vetoes as a means of probing colour flow in hard scattering processes in hadronic collisions. As an example, I describe a calculation of the dijet cross-section with a jet veto which resums the leading logarithms of the veto scale and it is matched to a fixed-order computation. I compare this prediction to the measurement performed by the ATLAS collaboration as well as to other different approaches. Finally, I outline future developments in this research area.Speaker: Simone Marzani (IPPP / Durham University)
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Combined: Heavy flavours/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
08:30
New Heavy Flavor Contributions to the DIS Structure Function F_2(x,Q2) at O(\alpha_s3) 20mWe report on recent results obtained for the massive Wilson coefficients which contribute to the structure function $F_2(x,Q2)$ at $O(\alpha_s2)$ and $O(\alpha_s3)$ in the region $Q2/m2 \gsim 10$ for general values of the Mellin variable $N$ as well as to corresponding operator matrix elements emerging in FVNSs.Speaker: Johannes Bluemlein (DESY, Zeuthen)
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08:50
Heavy Quark Production in the ACOT Scheme at NNLO and N3LO 20mWe analyze the properties of the ACOT scheme for heavy quark production and make use of the MS-bar massless results at NNLO and N3LO for the structure functions F2 and FL in neutral current deep-inelastic scattering to estimate the higher order corrections. For this purpose we decouple the heavy quark mass entering the phase space from the one entering the dynamics of the short distance cross section. We show numerically that the phase space mass is generally more important. Therefore, the dominant heavy quark mass effects at higher orders can be taken into account using the massless Wilson coefficients together with an appropriate slow-rescaling prescription implementing the phase space constraints. Combining the exact ACOT scheme at NLO with these expressions should provide a good approximation to the missing full calculation in the ACOT scheme at NNLO and N3LO.Speaker: Fred Olness (Southern Methodist University)
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09:10
On the NNLO QCD corrections to deep-inelastic heavy-quark production 20mWe present exact results for the heavy-quark structure functions in deep-inelastic scattering (DIS) in different kinematical regimes and to next-to-next-to-leading order (NNLO) in perturbative QCD. We combine the behavior near threshold, in the high-energy limit and at asymptotically large $Q2 \gg m2$ to derive approximate expressions at NNLO accuracy. The remaining theoretical uncertainties of this approximation are negligible except in a region of small-$x$ and low $Q2$ and we illustrate the improvement in precision predictions for heavy-quark DIS.Speaker: Sven-Olaf Moch (DESY, Zeuthen)
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The singular behavior of one-loop massive QCD amplitudes with one external soft gluon 20mI report on the calculation of the one-loop correction to the soft-gluon current with massive fermions. This current is process independent and controls the singular behavior of one-loop massive QCD amplitudes in the limit when one external gluon becomes soft. It therefore constitutes a necessary ingredient for the numerical evaluation of observables with massive fermions at hadron colliders to next-to-next-to-leading order.Speaker: Isabella Bierenbaum (University Hamburg)
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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08:30
The MSSM after two years of LHC running 18mThe LHC is closing in on the Minimal Supersymmetric Standard Model. The null results from superparticle searches, and the preliminary evidence for a 124-126 GeV Higgs, severely constrain various popular minimal scenarios. In this talk I will review these constraints, and point out how the LHC results can still be accommodated within the MSSM. The resulting superparticle mass spectra may provide interesting clues about the underlying model which generates the soft SUSY breaking terms.Speaker: Mr Felix Bruemmer (Heidelberg University)
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08:48
Searches with Jets + missing Et without leptons at CMS 18mWe present results of searches for SUSY production at CMS in events containing hadronic jets and missing energy. Various discriminants based on the event kinematics are employed to suppress standard-model backgrounds. The results are interpreted in the context of the Constrained Minimal Supersymmetric Standard Model, and of a number of "simplified models.Speaker: Saeid Paktinat Mehdiabadi (School of Particles and Accelerator Inst. for Res. in Fundam. S)
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09:06
Searches with Jets + missing Et with leptons at CMS 18mWe present results of searches for SUSY production at CMS in events with lepton signatures. These include final states with single isolated leptons, Z bosons decaying to lepton pairs, non-resonant same- and opposite-sign lepton pairs, and three or more isolated leptons. The results are used to exclude previously unexplored regions of the supersymmetric parameter space assuming R-parity conservation with the lightest supersymmetric particle being either a neutralino or gravitino.Speaker: Martin Niegel (KIT - Karlsruhe Institute of Technology (DE))
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09:24
Search for R-partity violating SUSY signatures with the ATLAS detector 18mSearches for supersymmetry at the LHC also embrace signatures from R-parity violating processes. These can be final states with resonant or non-resonant lepton flavour violation or multiple leptons. The talk presents recent results from searches for R-partity violation in events containing leptons based on data recorded in 2011 by the ATLAS detector.Speaker: Carsten Peter Meyer (Johannes-Gutenberg-Universitaet Mainz (DE))
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09:42
Searches for strong R-parity conserving SUSY production at the LHC with the ATLAS detector 18mSearches for supersymmetric squarks and gluinos in events containing jets, missing transverse momentum with or without leptons are presented. The results are based on the full data sample (5 fb-1) recorded in 2011 at sqrt(s)=7 TeV cebtre-of-mass energy by the ATLAS experiment at the LHC.Speaker: Federica Legger (Ludwig-Maximilians-Univ. Muenchen)
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
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08:30
PHENIX Upgrade Plans for the Next Decade 25mDuring 12 years of operations, PHENIX has measured the gluon helicity structure of the proton, probed the proton transverse spin structure, studied effects in cold nuclear matter, discovered a strongly coupled QGP and has studied many of its basic properties. In parallel with ongoing luminosity upgrades at RHIC, PHENIX is in the process of planning and commissioning a series of upgrades in order to systematically expand its physics capabilities, allowing measurement of the sea quark helicity distributions, the low x gluon distribution in heavy nuclei and charm and bottom quark production in Heavy Ion collisions. PHENIX is also planning a larger upgrade for the next decade to answer many of the questions spurred by our discoveries during the last decade. With increased acceptance and improved electromagnetic and new hadronic calorimetry in the central region, we will advance understanding of the sQGP by studying jet energy loss. We also plan to upgrade our forward physics detector with additional calorimetry and tracking acceptance. This will allow for measurements of the Sivers effect in Drell-Yan, which can test our understanding of QCD factorization. The larger acceptance will improve our access to low x distributions in heavy nuclei, and also enable measurements of jets in the forward direction, which will allow for a more systematic approach to understanding the large transverse spin measurements seen at RHIC.Speaker: Dr Kieran Boyle (RIKEN BNL Research Center)
- 08:55
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Accelerator Design of High Luminosity Electron-Hadron Collider eRHIC 25mThe accelerator design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC is presented. We plan adding energy recovery linacs to accelerate the electron beam to 20 (potentially 30) GeV and to collide the electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10^34 cm^-2 s^-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. The important eRHIC R&D items include the high-current polarized electron source, the coherent electron cooling and the compact magnets for re-circulating passes. A natural staging scenario is based on step-by-step increases of the electron beam energy by building-up of eRHIC's SRF linacs.Speaker: Vadim Ptitsyn (B)
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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Insights into the nucleon spin from lattice QCD 35mFlavour singlet contributions to the nucleon spin are elusive due to the fact that they cannot be determined directly in experiment but require extrapolations to the small x region. Direct calculations of these contributions are possible using Lattice QCD, however, they pose a significant computational challenge due to the presence of disconnected quark line diagrams. I report on recent progress in determining these sea quark contributions on the lattice.Speaker: Sara Collins (University of Regensburg)
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HERMES latest results on phi meson spin density matrix elements 25mThe HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson (rho,phi,omega) leptoproduction using the 27.6 GeV self-polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas target. The latest results on spin density matrix elements of exclusive phi meson production using the full statistics collected at HERMES, are presented. Conclusions on the helicity amplitudes, which are related to spin density matrix elements, are also presented.Speaker: Mayya Golembiovskaya (DESY)
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09:30
Fragmentation functions at Belle 25mFragmentation functions (FFs) describe the formation of final state particles from a partonic initial state. Precise knowledge of these functions is a key ingredient in accessing quantities such as the nucleon spin structure in semi-inclusive deep inelastic scattering and proton proton collisions. However, fragmentation functions can currently not be determined from first principles Quantum Chromodynamics and have to be extracted from experimental data. The Belle experiment at KEK, Japan, provides a large data sample for high precision measurements of quantities allowing for first-time or more precise extractions of fragmentation functions. Completed and ongoing analyses for extractions of spin-independent (unpolarized FFs) as well as spin-dependent fragmentation functions (Collins and Interference FFs) at Belle will be presented.Speaker: Mr Martin Leitgab (University of Illinois at Urbana-Champaign)
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Coffee break 20m
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Combined: Hadronic final states/diffraction and vector mesons Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
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10:30
Dijet Production in QCD and N=4 SYM 20mPerturbative N=4 SYM computations for dijet production within the BFKL regime are shown to approach closely QCD predictions for suitable observables sensitive to the Möbius invariance of Regge limit. This similarity is strengthened by an appropriate choice of renormalization scale.Speaker: José Daniel Madrigal (IFT UAM/CSIC, Madrid)
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10:50
Next-to-leading and resummed BFKL evolution with saturation boundary 20mWe investigate the effects of the saturation boundary on small-x evolution at the next-to-leading order accuracy and beyond. We demonstrate that the instabilities of the next-to-leading order BFKL evolution are not cured by the presence of the nonlinear saturation effects, and a resummation of the higher order corrections is therefore needed for the nonlinear evolution. The renormalization group improved resummed equation in the presence of the saturation boundary is investigated, and the corresponding saturation scale is extracted. A significant reduction of the saturation scale is found, and we observe that the onset of the saturation corrections is delayed to higher rapidities. This seems to be related to the characteristic feature of the resummed splitting function which at moderately small values of x possesses a minimum.Speaker: David Zaslavsky (Penn State University)
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NLO BFKL jet phenomenology with Lipatov's high energy effective action 20mWe report on recent progress in the evaluation of next-to-leading order (NLO) corrections to forward-backward jet observables, using Lipatov's QCD high energy effective action. We calculate both real and virtual corrections to the quark induced forward jet vertex at NLO, making use of a new regularization method and a subtraction mechanism. We also present the real NLO corrections to the quark induced Mueller-Tang jet vertex. Together with the already know virtual corrections it will allow for the construction of the complete NLO Mueller-Tang jet impact factor which is the only missing element for a complete NLO BFKL description of jet events with rapidity gap.Speaker: Dr Martin Hentschinski (IFT UAM/CSIC Madrid)
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Resummation of large-x and small-x double logarithms in DIS and semi-inclusive e+e- annihilation 20mRecently a method has been developed to extend the resummation of large-x double logarithms in inclusive DIS and semi-inclusive e^+e^- annihilation (SIA) to terms and quantities not addressed by the soft-gluon exponentiation. The N^nLL (leading log, next-to-leading log etc) resummation is based on N^nLO fixed-order results, the large-x structure of DIS and SIA in dimensional regularization and the all-order factorization of mass singularities. The same formalism can be applied to the dominant x-1 ln^{2*n-a-n_0} x terms in SIA splitting functions and coefficient functions and the (in the flavour-singlet case) subdominant x0 ln^{2*n-a-n_0} x contributions to (most of) their DIS counterparts. The talk addresses the theoretical basics of these resummations and presents the main numerical results which, despite all formal similarities, are qualitatively different for DIS and SIA.Speaker: Andreas Vogt (University of Liverpool)
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Combined: Heavy flavours/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
10:30
Measurement of charm production in DIS with D* mesons and extraction of F2cc 18mCharm production has been measured with the ZEUS detector in deep inelastic ep scattering at HERA. The measurement is based on the full reconstruction of the decay chain D*->D0pis, D0->Kpi and exploits the full HERA II statistics. Differential cross sections have been measured. The kinematic range is 1.5 GeV < pT(D*) < 10GeV, |eta(D*)| < 1.5, 5 < Q2 < 1000GeV2 and 0.02 < y < 0.7. The observed cross sections is extrapolated to the full pt(D*) and eta(D*) range in order to determine the open-charm contribution, F2cc(x,Q2) to the proton structure function, F2.Speaker: Andrii Gizhko (Kiev University + DESY)
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10:48
Charm production in DIS using inclusive secondary vertices and extraction of F2cc 18mCharm production in deep inelastic scattering has been measured with the ZEUS detector using the full HERA II data set. The charm content in events with a jet has been extracted using the decay length significance and invariant mass of secondary vertices. Differential cross sections as a function of Q2, Bjoerken x, ET(jet) and eta(jet) were measured and compared to theoretical predictions. The open charm contribution to the proton structure function F2 was extracted from double differential cross sections.Speaker: Vladislav Libov (DESY)
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11:06
Measurement of D^{*\pm} Meson Production and Determination of F_2^{ccbar} at low Q2 in Deep-Inelastic Scattering at HERA 20mInclusive production of D* mesons in deep-inelastic ep scattering at HERA is studied in the range 5 < Q^2 <100 GeV^2 of the photon virtuality and 0.02 < y < 0.7 of the inelasticity of the scattering process. The observed phase space for the D* meson is p_T(D*) > 1.25 GeV and |eta(D*)| < 1.8. The data sample corresponds to an integrated luminosity of 348 pb^{-1} collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution F_2^{ccbar} to the proton structure function F_2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.Speaker: Eva Hennekemper (Uni Heidelberg)
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Electroweak and searches Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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10:30
Supersymmetry beyond the MSSM after the first LHC data 18mWe review the status of motivated beyond-MSSM scenarios in the light of the first searches at the LHC. In particular, we discuss the consequences for model building of a Higgs boson at about 125 GeV and of taking seriously the excess in the direct CP violation in the charm sector.Speaker: Paolo Lodone (Scuola Normale Superiore of Pisa)
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10:48
Search for supersymmetry in events involving third generation squarks and sleptons with ATLAS 18mSupersymmetry with large mixing between left and right scalar fermions predicts that the lightest partners of the SM fermions belong to the third generation. Moreover, naturalness arguments favour stop masses not too far from that of the top quark. The talk presents results from searches for gluino mediated sbottom and stop production, direct sbottom production, and gluino and squark mediated stau production using data recorded with the ATLAS detector in 2011.Speaker: Carlos Chavez Barajas (CERN)
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11:06
Searches for direct supersymmetric gaugino production with the ATLAS detector 18mNaturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the Higgs and electroweak gauge bosons, so-called gauginos, with masses not too far from those of their Standard Model counterparts. Gauginos with masses less than a few hundred GeV can give rise to direct pair production rates at the LHC that can be observed in the data sample recorded in 2011 by the ATLAS detector. The talk presents results from searches for direct gaugino production in final states with leptons and missing transverse momentum.Speaker: Louise Heelan (University of Texas at Arlington (US))
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11:24
SUSY searches with Photons at CMS 18mWe present results of searches for SUSY production at CMS in events with one or two isolated photons. The results are interpreted in terms of gauge-mediation models, with the gravitino as the lightest supersymmetric particle.Speaker: Dongwook Jang (Carnegie-Mellon University (US))
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11:42
Searches for SUSY with third-generation signatures in CMS 18mWe present results of searches for SUSY production at CMS in events containing hadronic jets and missing energy. The tagging of heavy flavor in the jets is used both to distinguish standard-model components, and for sensitivity to those SUSY models that lead to final states rich in heavy-flavored particles.Speaker: Alexis Kalogeropoulos (Inter-University Institute for High Energies (BE))
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
- 10:30
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10:55
The STAR Experiment: The second decade and beyond. 40mThe STAR experiment is one of the flagship experiments at the Relativistic Heavy-Ion Collider at Brookhaven Lab. Since starting to take data at the turn of the century, STAR’s large acceptance and measurement capabilities have proved to be vital in terms of characterising the QGP soup produced in heavy-ion collisions and heading towards a measurement of the proton spin in polarised p+p collisions. This has only been achieved through the constant upgrade and enhancement of detectors and components every year, one of many examples being the recordable DAQ rate increasing by a factor of 10^3 since the first year. Although many measurements have been performed in the last decade, much remains to be done. In this presentation I will outline the proposed measurements and corresponding detector upgrades over the next decade in p+p, p+A and A+A physics as well as STAR’s role in the transition of RHIC to an eRHIC accelerator complex.Speaker: Dr Matthew Lamont (BNL)
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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10:30
Transverse single spin asymmetries 35mLarge transverse single spin asymmetries (SSAs) of cross sections with a large momentum transfer in high energy collisions were once thought impossible in QCD. With over 30 years of experimental as well as theoretical efforts, large SSAs are not only possible in QCD, but also carry extremely valuable information on the motion and structure of quarks and gluons inside a polarized hadron. In this talk, I will review the physics behind the measured SSAs and the twist-3 mechanism to generate the SSAs. I will also discuss the transition between TMD factorization approach to twist-3 collinear factorization approach to SSAs.Speaker: Dr Jian-Wei Qiu (Brookhaven National Lab)
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11:05
PHENIX Transverse Spin Physics Results 25mUtilizing the RHIC polarized proton collider with transverse spin the PHENIX detector carried out cross section and asymmetry measurements in inclusive pizero and eta production at mid rapidity |n| < 0.35 using the central EM calorimeters where vanishing asymmetries were found. However, significant pizero and eta asymmetries were measured in the forward rapidity 3.1 < n < 3.9 using the MPC calorimeter. An inclusive cluster analysis of the MPC data also resulted in significant asymmetries. We will discuss the results in terms of energy dependence, the Sivers or Collins contributions at low transverse momentum, and higher Twist approaches at higher momenta. Future plans such as a inclusive jet production and Drell Yan measurements will also be presented.Speaker: Dr Yousef Makdisi (Brookhaven National Laboratory)
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11:30
Single and Double Spin Asymmetry Measurements in Semi-Inclusive and Inclusive DIS on Polarized He-3 25mJefferson Lab experiment E06-010 measured the target-single spin (SSA) and double spin asymmetries (DSA) in semi-inclusive deep inelastic pion electroproduction on a transversely polarized He-3 target. The measured asymmetry (A_UT) is sensitive to the nucleon transversity and Sivers distribution functions, whereas the measured A_LT asymmetry is related to the transverse momentum dependent PDF g_1T. The kinematics were chosen to be in the valence quark region with x ~ 0.16-0.35 and Q^2 ~ 1.4-2.7 GeV^2. The Collins moment, which is sensitive to transversity, the Sivers and A_LT moments, which are sensitive to the orbital motion of the quarks, were extracted using the azimuthal angular dependence of the measured asymmetries. These data, when combined with the data from other experiments on transversely polarized proton and deuteron targets, will help in extracting the nucleon transverse momentum dependent distribution functions via a global analysis. These semi-inclusive results will be presented and discussed along with the preliminary results for the inclusive single spin asymmetries.Speaker: Vincent Sulkosky (MIT)
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10:30
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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11:30
Quarkonium Production in ATLAS 18mThe production of Quarkonium is an important testing ground for QCD calculations. The J/ psi and Upsilon production cross-sections are measured in proton-proton collisions at the ATLAS detector. Differential cross sections as a function of transverse momentum and pseudorapidity will be presented. The fraction of J/\psi produced in $B$-hadron decays are also measured and the differential production cross-sections of prompt and non-prompt J/ \psi determined separately. Results are compared to predictions from perturbative QCD calculations.Speaker: Susan Cheatham (McGill University (CA))
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Structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
11:30
Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data 20mThe impact of isolated-photon data from proton-(anti)proton collisions at RHIC, SppbarS, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-gamma measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20%) of its uncertainties around fractional momenta x~0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20% at the LHC. We conclude that present and future isolated-photon measurements constitute an interesting addition to coming global PDF analyses.Speaker: David d'Enterria (CERN)
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11:50
HERAFitter 20mHERAFitter, a common initiative of the H1 and ZEUS collaborations, is an open source software package which provides a framework for precision QCD analyses, based on the evolution package of QCDNUM. The beta-release of the HERAFItter package contains a set of programs to fit inclusive deep inelastic scattering cross section data from HERA as well as Drell-Yan and inclusive jet processes, which are included using APPLGRID and FastNLO interfaces. HERAFitter provides an optimal platform to perform elaborate benchmarking studies of different theoretical models with rigorous treatment of experimental uncertainties. The package enables the determination of the proton parton density functions (PDFs) using precise data from LHC.Speaker: Voica Ana Maria Radescu (Deutsches Elektronen-Synchrotron (DE))
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Lunch break 1h 20m Mensa Poppelsdorf
Mensa Poppelsdorf
University of Bonn
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Combined: Diffraction and vector mesons/spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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13:30
Imaging partons using exclusive scattering processes 25mThe spatial distribution of partons in the proton or a nucleus can be probed in suitable exclusive scattering processes. I review the theoretical foundation and the physics interest of this idea, and I report on recent performance estimates for parton imaging in the proton at an Electron-Ion collider.Speaker: Markus Diehl (DESY)
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13:55
GPD analysis of hard scattering processes : progress report 20mWe present some recent results on the analysis of hard scattering processes in the framework of Generalized Parton Distributions. In particular we compute DVCS observables on unpolarized targets with the Kroll - Goloskokov model (suited to DVMP analysis). We also discuss NLO contributions to DVCS and TCS processes for various kinematic settings (collider and fixed target experiments).Speaker: Hervé MOUTARDE (I)
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14:15
Spin structure of the "forward" nucleon charge-exchange reaction n + p ---> p + n and the deuteron charge-exchange breakup 20mThe structure of the nucleon charge-exchange process n + p --> p + n is investigated basing on the isotopic invariance of the nucleon-nucleon scattering. Using the operator of permutation of the spin projections of the neutron and proton, the connection between the spin matrices, describing the amplitude of the nucleon charge-exchange process at zero angle and the amplitude of neutron elastic scattering on the proton in the "backward" direction, has been considered. Due to the optical theorem, the spin-independent part of the differential cross-section of the process n + p --> p + n at zero angle for unpolarized particles is expressed through the difference of total cross-sections of unpolarized proton-proton and neutron-proton scattering. Meantime, the spin-dependent part of this cross-section is proportional to the differential cross-section of the deuteron charge-exchange breakup d + p --> (pp) + n at zero angle at the deuteron momentum {\bf k}_d = 2{\bf k}_n ( {\bf k}_n is the initial neutron momentum ). Analysis shows that, assuming the real part of the spin-independent term of the "forward" amplitude of the process n + p --> p + n to be smaller or of the same order as compared with the imaginary part, in the wide range of neutron laboratory momenta k_n > 700 MeV/c the main contribution into the differential cross-section of the process n + p --> p + n at zero angle is provided namely by the spin-dependent term .Speaker: Dr Valery Lyuboshitz (Joint Institute for Nuclear Research, Dubna, Russia)
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14:35
Overview of Deeply Virtual Compton Scattering at HERMES 20mDeeply Virtual Compton Scattering represents the best experimental channel through which to understand Generalised Parton Distributions. The HERMES experiment measured the most diverse set of DVCS results of any experiment; this talk discusses the most recent sets of DVCS results released by HERMES and the unique experimental conditions found at HERMES that facilitated the measurements. We also examine the various ways in which the HERMES experimental measurements are being used to constrain GPDs and how future experiments can learn from the HERMES program.Speaker: Morgan Murray (U)
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14:55
Vector Meson Production and DVCS at CLAS and CLAS12 20mGeneralised Parton Distributions (GPDs) offer an insight into the three-dimensional structure of the nucleon and its internal dynamics, relating the transverse position of quarks to their longitudinal momentum. Two effective means of accessing GPDs are Deeply Virtual Compton Scattering (DVCS) and Meson Production (DVMP), in which a high energy electron scatters from a single quark in the nucleon and, respectively, a real photon or meson is produced as a result. Jefferson Laboratory (JLab), USA, is ideally suited for measuring these processes and a very active experimental programme has been underway in the recent years, making use of the lab's continuous electron beam up to 6 GeV in energy and its large angle spectrometer CLAS. In the future, a vast, new, as-yet unprobed kinematic region will become experimentally accessible when the current upgrade of the JLab accelerator to operate at a maximum energy of 12 GeV is completed in a few years. It is being complemented by the construction of a new suite of detectors, CLAS12, a number of them optimised specifically for exclusive reconstruction of DVCS and DVMP in the new kinematic region. We present a selection of recent results of DVCS and DVMP measurements using CLAS and introduce the exciting experimental programme planned for the future with CLAS12.Speaker: Dr Daria Sokhan (in2p3)
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15:15
Hard Exclusive Meson Production at COMPASS and Future DVCS Measurements at COMPASS-II 20mNew results for the transverse target spin azimuthal asymmetry $A_{UT}^{\sin(\phi-\phi_S})$ for hard exclusive $\rho^0$-meson production on a transversely polarised NH$_3$ target will be presented. The measurement was performed in 2007 and 2010 with the COMPASS detector using the 160\,GeV/$c$ muon beam of the SPS at CERN. The asymmetry is sensitive to the nucleon helicity-flip generalised parton distributions $E^q$, which are related to the orbital angular momentum of quarks in the nucleon. The DVCS program of the future COMPASS-II experiment, dedicated to investigate the nucleon structure through Generalised Parton Distributions is presented as well. The high energy muon beam from CERN SPS allows to measure these processes in a wide and up to now uncovered range in Bjorken $x$ and $Q^2$. The availability of muon beams with opposite charges and polarisations provides unique possibilities to access the GPDs.Speaker: Heiner Wollny (CEA - Centre d'Etudes de Saclay (FR))
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Combined: Electroweak and searches/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
13:30
Z' production in an extended MSSM 18mSearching for heavy neutral gauge bosons Z', predicted in extensions of the Standard Model based on a U(1)' gauge symmetry, is among the main new physics investigations undertaken by the experiments at the Tevatron and at the Large Hadron Collider. I will discuss study Z' phenomenology at hadron colliders according to several U(1)'-based models and in the Sequential Standard Model. In particular, as far as its decay is concerned, we shall include possible Z' decays into supersymmetric particles, besides the Standard Model modes so far investigated. Results on branching ratios and cross sections will be presented, as a function of the MSSM and U(1)' parameters, which will be varied within suitable ranges. Special attention will be paid to the decay into chargino, neutralino and charged-slepton pairs and gauge the feasibility to discover supersymmetry through this channel at the LHC.Speaker: Gennaro Corcella
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13:48
Measurements of dibosons with the ATLAS detector and associated constraints on new physics 18mDiboson cross sections have been measure for all combinations of W,Z and isolated photons. The cross sections are measured in kinematic regions defined by the decay kinematics, in some cases including vetoes on additional jets. The measurements are also extrapolated to the full phase space using theoretical calculations of the acceptance, and are additionally used to place contsraints on triple-gauge boson couplings.Speaker: Hugh Skottowe (Harvard University (US))
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14:06
Diboson Measurements with the CMS Detector 18mWe present studies of diboson production in pp collisions at 7 TeV center-of-mass energy based on data recorded by the CMS detector at the LHC in 2010 and 2011. These include precise measurements of W and Z production in association with a photon and of WW production, WZ and ZZ productions at the LHC. The leptonic decay modes of the W and Z bosons are used. The results are interpreted in terms of constraints on anomalous triple gauge couplings.Speaker: Santiago Folgueras (Universidad de Oviedo (ES))
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W mass measurements from the Tevatron 18mThe CDF collaboration has analyzed 2.2 fb-1 of Run II electron and muon data for a new precise determination of the mass of the W boson. The result is 80.387 +/- 0.019 GeV/c2, which is more precise than the combination of all preceding measurements. An update from D0 is also expected.Speaker: Tom Riddick
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15:00
Elastic Z0 production at HERA 18mA search for events ep-> ep Z0 has been performed in ep collisions at HERA using the ZEUS detector. The search is based on the entire HERA-I and HERA-II data set, amounting to 0.49 fb-1 of integrated luminosity. The Z0 was searched in the di-jet decay mode with elastic condition defined by etamax < 3, where etamax is defined as the pseudorapidity of the energy deposit in the calorimeter closest to the proton beam direction. A di-jet mass peak is observed at the Z0 mass and the number of signal events is extracted from a fit to the mass spectrum. The elastic Z0 production cross section is determined and compared to the SM prediction.Speaker: Takuya Nobe (Tokyo Institute of Technology (JP))
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
- 13:30
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14:40
An eRHIC Detector: Design Consideration and its Realization by Means of Detector R&D 25meRHIC is a proposed high luminosity, polarized Electron Ion Collider (EIC), which would make use of the existing RHIC infrastructure. eRHIC is a triple IP collider, with the possibility of using the two existing, but upgraded IP detectors and a dedicated eRHIC detector. A detector has to be designed that can make use of present knowledge and experience gained from the HERA detectors, but has to be adapted such that it is able to cope with the EIC physics program. This presentation will describe the eRHIC detector design and its IR as well the presently ongoing R&D activities for making technology choices towards such a detector.Speaker: Klaus Dehmelt (Stony Brook University USA)
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ePHENIX for eRHIC 20mAddition of a high intensity polarized electron beam facility which could realize Deep Inelastic Scattering (DIS) research with one of the RHIC beams is one of the future upgrades to the Relativistic Heavy Ion Collider (RHIC) presently under consideration. To take a full advantage of such machine evolution, after more than a decade of exciting physics results, both with heavy ion and polarized proton collisions, PHENIX Collaboration has launched a detector upgrade study consistent with the above collider upgrades, going in to the eRHIC era. We discuss a staged approach of the PHENIX upgrade program and physics topics we plan to address with the e-p and e-A collisions at eRHIC.Speaker: Alexander Bazilevsky (B)
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
- 13:30
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13:50
Inclusive particle production 20mDue to its unique pseudorapidity coverage and the possibility of providing measurements at low transverse momenta, the LHCb detector allows unique insight into particle production in the forward region at the LHC. The latest LHCb soft-QCD results, the measurements of charged particle multiplicity at 7 TeV and the measurement of the p/p, K-/K+, π-/π+, (p+p)/(π-+π+), (K-+K+)/( π-+π+ ) production ratios at 0.9 TeV and 7 TeV will be presented. These results offer an important input to the understanding of baryon transport and of the hadronisation process in a kinematical range where QCD models have large uncertainties.Speaker: Markward Britsch (Max-Planck-Gesellschaft (DE))
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14:10
Pion and Kaon multiplicities from muon-deuteron deep inelastic scattering at COMPASS 20mFragmentation functions, which turn partons into non-perturbative hadronic bound states in hard-scattering reactions, play a very important role in our understanding of the proton structure. Currently, our knowledge of fragmentation functions originates mainly from existing global QCD analyses which are mostly based on inclusive measurements in electron-positron annihilation process. While the latter mainly fixes the flavour singlet combinations of fragmentation functions, semi-inclusive deep inelastic scattering gives access to the flavour structure of FFs via hadron multiplicities. The COMPASS collaboration has recently measured pion and kaon multiplicities, in different combinations of bins in x, z and Q2, using 160 GeV/c muons off deuteron target. This measurement makes an experimental contribution for a deeper understanding on the fragmentation process.Speaker: Ms Nour Makke (Trieste UNiversity, INFN)
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14:30
Multidimensional Hadron Attenuation 20mHadron multiplicity ratios in semi-inclusive deep-inelastic scattering have been measured on neon, krypton and xenon targets relative to deuterium using the 27.6 GeV beam of HERA at the HERMES experiment. They are presented for pions (π+, π-), kaons (K+, K-), protons and anti-protons as a function of the virtual photon energy ν, its virtuality Q2, the fractional hadron energy z and the transverse hadron momentum pt with respect to the direction of the virtual photon. Dependences are presented in a two-dimensional representation, in the form of detailed binning over one variable and three slices over the other variable. These results may help to understand some aspects of the hadronization process.Speaker: Mr Gevorg Karyan (A.I. Alikhanyan National Science Laboratory)
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14:50
Scaled Momentum Distributions for K^0_s and Lambda/anti-Lambda in DIS at HER 20mScaled momentum distributions for the strange hadrons K0s and Lambda/Lambdabar were measured in deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb-1. The evolution of these distributions with the photon virtuality, Q2, was studied in the kinematic region 10 < Q2 < 40000 GeV2 and 0.001 < x < 0.75, where x is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Tuned leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next-to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from e+e- data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including e+e-, ep and pp data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding K0s and Lambda/Lambdabar strange hadrons.Speaker: Iris Abt (Werner-Heisenberg-Institut)
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15:10
On the pair correlations of neutral K, D, B and B_s mesons with close momenta produced in inclusive multiparticle processes 20mThe phenomenological structure of inclusive cross sections of the production of two neutral K mesons in hadron-hadron, hadron-nucleus and nucleus-nucleus collisions is investigated taking into account the strangeness conservation in strong and electromagnetic interactions. Relations describing the dependence of the correlations of two short-lived and two long-lived neutral kaons $K^0_S K^0_S$, $K^0_L K^0_L$ and the correlations of "mixed" pairs $K^0_S K^0_L$ at small relative momenta upon the space-time parameters of the generation region of $K^0$ and $\bar{K}^0$ mesons have been obtained. These relations involve the contributions of Bose-statistics and S-wave strong final-state interaction of two $K^0$ ( $\bar{K}^0$ ) mesons as well as of a $K^0$ meson with a $\bar{K}^0$ meson, and also the contribution of transitions $K^+ K^- --> K^0 \bar{K}^0$, and they depend upon the relative fractions of produced pairs $K^0 K^0$, $\bar{K}^0\bar{K}^0$ and $K^0\bar{K}^0$. It is shown that under the strangeness conservation the correlation functions of the pairs $K^0_S K^0_S$ and $K^0_L K^0_L$, produced in the same inclusive process, coincide, and the difference between the correlation functions of the pairs $K^0_S K^0_S$ and $K^0_S K^0_L$ is conditioned by the production of the pairs of non-identical neutral kaons $K^0 \bar{K}^0$. Analogous correlations for the pairs of neutral heavy mesons $D^0$, $B^0$ and $B_s^0$, generated in multiple processes with the charm (beauty) conservation, are analyzed, and differences from the case of neutral K mesons are discussed .Speaker: Dr Valery Lyuboshitz (Joint Institute for Nuclear Research, Dubna, Russia)
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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13:30
Testing NRQCD factorization with J/psi yield and polarization at NLO 18mWe study the polarization observables of $J/\psi$ hadroproduction at NLO in NRQCD, including the $^3\!P_J^{[8]}$ channel. Exploiting the color-octet long-distance matrix elements previously extracted through a global fit to unpolarized $J/\psi$ production data, we provide theoretical predictions in the helicity and Collins-Soper frames and compare them with data from CDF and ALICE. The notorious CDF $J/\psi$ polarization anomaly familiar from leading-order analyses persists at the quantum level, while the situation looks promising for the LHC.Speaker: Prof. Bernd Kniehl (Univ. Hamburg)
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13:48
Charmonium production in pp collisions with ALICE 18mDue to their large mass, heavy quark pairs are considered to be produced in the first instants of the collision in hard scatterings of partons which can be described perturbatively. However, the bound states of these pairs are produced via soft non-perturbative processes. The interplay between the perturbative and non-perturbative processes involved in quarkonium production makes this field a very important testing ground for QCD. At the LHC, the special setup of the ALICE experiment allows the study of charmonium production in pp collisions down to zero transverse momentum in a large rapidity range, $|y|<0.9$ and $2.5<y<4.0$. We will present results on charmonium production from pp collisions recorded by ALICE at $\sqrt{s}=$~2.76 and 7 TeV. These will include, among others, the first LHC measurements on $J/\psi$ polarization and the dependence of $J/\psi$ production on the event charged particle multiplicity. The data will be discussed using calculations from different theoretical models. We will also show results on the $J/\psi$ production in Pb--Pb collisions at $\sqrt{s_{NN}}=$~2.76 TeV in comparison with the pp collisions.Speaker: Ionut Cristian Arsene (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))
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J/psi Photoproduction in ultra-peripheral Au+Au collisions measured by RHIC-PHENIX. 18mTitle:J/psi Photoproduction in ultra-peripheral Au+Au collisions measured by RHIC-PHENIX. Ultra-peripheral collisions are heavy-ion collisions with impact parameter larger than twice the nuclear radius. Since there is no nuclear overlap, strong interactions cannot occur and ions interact through photon-ion (coherent), photon-nucleus (incoherent), and photon photon collisions. Measurement of vector meson photo production is a sensitive probe of gluon distribution in nuclei. At RHIC energy, measurement of J$/\psi$ photo production corresponds to x $\cong$ 0.015 and Q$^{2}$ =2.5 $GeV/c^2$. In the kinematic region, nuclear shadowing plays an important role and that still have large uncertainty. PHENIX has the capability of measuring J$/\psi$'s via their dielectron decays at mid-rapidity ($|y|<0.35$) and dimuon decays at forward (1.2$<|y|<$2.2) rapidity. PHENIX published J$/\psi$ photo production cross section at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV in the 2004 dataset [1] (add reference in the end). The measured cross section was found to be consistent with theoretical calculations within its statistical error. PHENIX collected higher statistics Au+Au collisions datasets in 2007 and 2010 that allow a more precise measurement over a wider rapidity range. In this talk I will present present new preliminary results for the integrated and differential cross section of UPC J$/\psi$ at central and forward rapidity.Speaker: Mr Akihisa Takahara (CNS, University of Tokyo and JRA RIKEN)
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Production of HF and quarkonia at CDF 18mWe report recent studies on heavy flavor production in 1.96 TeV proton-antiproton collisions collected by the CDF detector. These include a new measurement of the spin-alignment of Y mesons using dimuon decays in 6.7 fb^-1 of data. This measurement is the first to report the full angular distributions of dimuons as functions of Y transverse momentum in both the Collins–Soper and s–channel helicity frames. This is also the first measurement of spin alignment of Υ(3S) mesons.Speaker: Manuel Kambeitz
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14:42
Quarkonium results from LHCb 18mStudies of quarkonia production in the forward region provide important tests of NRQCD. During 2010 and 2011 the LHCb experiment has collected a dataset corresponding to an integrated luminosity of 1 fb-1 in proton-proton collisions at sqrt(s)= 7 TeV. We present studies based on 40 to 1000 fb-1 of data, including the production of the J/psi, psi(2S), Chi_c charmonium together with Upsilon and Chi_b bottomonium states. We also report measurements of double charm production, performed for the first time at a hadron collider. Absolute and relative branching ratios are presented and compared to the most recent theoretical predictions when available. In addition, we will discuss results for the exotic states the X(3872), Y(4140) and Z+(4430), and give prospects for these measurements.Speaker: Giovanni Sabatino (Universita degli Studi di Roma Tor Vergata (IT))
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15:00
Charmonium results at Belle 18mWe present recent results on charmonium and charmonium-like states studied by the Belle experiment at the KEK-B e+e- collider. After years of interesting discoveries in the field of hadron spectroscopy, Belle continues the research by measuring new final states produced in various processes accessible at the B-Factories. Main motivation is to complete the spectrum of charmonia predicted by QCD and to investigate the nature of so called X,Y,Z states.Speaker: Jolanta Brodzicka (INP Krakow)
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15:18
Charmonium and charmonium-like results from BABAR 18mCharmonium and charmonium-like states are a unique system for studying QCD and possibly exotic bound states. We present new results on such states, which are created in two-photon fusion or in electron-positron collisions and decaying into a variety of final states, including psi pi pi, eta_c pi pi, and J/psi omega.Speaker: Elisa Fioravanti (INFN Ferrara)
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Coffee break 20m
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Combined: Electroweak and searches/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
16:00
W/Z/DY + jet as a test of the NLO BFKL kernel 18mWe study W/Z/DY + jet events where the W/Z/DY boson is produced in the forward direction of one of the colliding protons and a jet is produced in the forward direction of the second proton. The resulting large rapidity difference between the final states then opens up the phase space for BFKL evolution which we would like to study in more detail. As a by-product of our study, we also provide an analytic expression for the high energy re-summed exclusive partonic W/Z + n jet cross-section in moment space. To construct the BFKL re-summed cross-section we determine an analytic expression for the exclusive W/Z/DY impact factor in (gamma, n) space which is combined with BFKL Green's function and jet impact factor. In particular, both impact factors are determined for non-zero conformal spin and allow therefore for the study of angular correlations. First numerical results for a number of observables which allow to isolate and test BFKL evolution are presented.Speaker: Martin Hentschinski (Autonoma University Madrid/CSIC)
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16:18
Measurements of W/Z production with the ATLAS detector 18mW and Z boson production have been measured in the electron, muon and tau decay channels. Total and differential cross sections, defined in terms of the decay lepton kinematics, have been measured as a function of rapidity and transverse momentum. Ratios of the cross sections demonstrate sensitivity to lepton universality, and the kinematic distributions constrain parton densities and QCD calculations including resummations of soft gluon radiation, and the matching of NLO matrix elements or high multiplicity tree-level matrix elements to parton shower approximations. The polarisation of W bosons is also measured, as, for the first time, is the polarisation of the tau lepton in W-->tau nu decays.Speaker: Jean-Baptiste Sauvan (Universite de Paris-Sud 11 (FR))
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16:36
Measurement of W and Z production in the forward region with LHCb 18mWe report on measurements of W and Z production in the forward region, using data collected at the LHCb experiment with a centre of mass energy of $\sqrt{s}=7$~TeV with an integrated luminosity of up to 1 fb-1. W and Z bosons are reconstructed in leptonic decay channels, and their cross-sections determined using data-driven techniques. Results are presented inclusively (within the fiducial region considered), and differentially as a function of boson rapidity (Z) and lepton pseudorapidity (W). The ratio of W to Z production, W+/W- production and the W charge asymmetry (for three lepton PT thresholds) is also given. All results are compared to NNLO predictions.Speaker: Mr Stephen Farry (University College Dublin (IE))
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16:54
Production of Z and W in association with heavy quarks at CMS 18mThe mechanism of production of heavy-flavoured mesons, containing b or c quarks, in association with vector bosons, W or Z, in the Standard Model is only partially understood. The study of events with one or two well-identified and isolated leptons accompanied by b-jets or secondary vertices is therefore crucial to refine the theoretical calculations in perturbative QCD, as well as validate associated Monte Carlo techniques. The deep understanding of these processes is furthermore required by Higgs and BSM analyses with similar final states. Using the LHC proton-proton collision data collected in 2010 and 2011 at a centre of mass energy of 7 TeV by the CMS detector, preliminary measurements of the Z+b(b) cross sections and angular correlations are presented. Finally, the study of the W+c production rate with respect to the W charge and W+light jets rates allows to probe the strange quark content of the proton. These results are also presented.Speaker: Marco Musich (INFN Torino (IT))
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17:12
Drell-Yan production in the forward region with LHCb 18mWe report on Drell-Yan production using data collected at the LHCb experiment with a centre of mass energy of $\sqrt{s}=7$~TeV in 2010. Drell-Yan events are selected with invariant di-muon masses $M_{\mu\mu}>10$~GeV/$c^2$. These measurements are sensitive to Bjorken-$x$ values as low as $1\times 10^{-5}$ and will provide important input to the knowledge of the parton density functions. The event selection and the signal extraction is described. The cross section is measured differentially as a function of the invariant mass of the two muons.Speaker: Jonathan Anderson (Universitaet Zuerich (CH))
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Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
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16:00
Measurement of the t dependence in exclusive photoproduction of Upsilon (1S) mesons at HERA 20mThe exclusive photoproduction reaction gamma p -> Upsilon(1S) p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468pb-1. The measurement covers the kinematic range 60 < W < 220 GeV and Q2 < 1 GeV2, where W is the photon--proton centre-of-mass energy and Q2 is the photon virtuality. The exponential slope, b, of the t dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured, yielding b=4.3 +2.0-1.3 (stat.) +0.5-0.6 (syst.) GeV2. This constitutes the first measurement of the t dependence of the gamma p -> Upsilon(1S) p cross section.Speaker: Jacek Ciborowski (University of Warsaw)
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16:20
Exclusive Electroproduction of two Pions at HERA 20mThe exclusive electroproduction of two pions in the mass range 0.4 < M(pipi) < 2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. The analysis was carried out in the kinematic range of 2 < Q2 < 80 GeV2, 32 < W <180 GeV and |t|<0.6 GeV, where Q2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |F(M(pipi)|, assuming that the studied mass range includes the contributions of the rho, rho' and rho'' vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios sigma(rho'->pipi)\sigma(rho) and sigma(rho''->pipi)/sigma(rho) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e+e- -> pipi.Speaker: Dr Justyna Tomaszewska (DESY)
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16:40
A holographic light-cone wavefunction for the rho wavefunction 20mWe obtain a very good description of the current HERA data on diffractive rho electroproduction using a holographic light-cone wavefunction for the rho meson. This holographic wavefunction is obtained using the Brodsky and de Teramond correspondance between hadronic modes in AdS space and light-cone wavefunctions in physical spacetime. We also show the corresponding holographic Distribution Amplitude is consistent with Sum Rules and lattice predictions.Speaker: Prof. Ruben Sandapen (University of Moncton (Canada))
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17:00
New determination of the nonperturbative form factor in QCD transverse-momentum resummation for vector boson production 20mIn the conventional b_* model for the Collins–Soper–Sterman resummation, the resummed form factor is accompanied by the nonperturbative gaussian form factor, and it is known that the nonperturbative parameter associated with the latter exhibits the strong dependence on the logarithm of the vector boson invariant mass. On the other hand, an another approach to treat the impact parameter (b space) transform in the resummation formalism has been developed as the ``minimal prescription (MP)'' based on an analytic continuation procedure. By contrast to the b_* approach, the MP has advantages that it leaves unchanged the perturbative expansion to any (and arbitrarily-high) fixed order in \alpha_s and it does not require any infrared cut-off to avoid the Landau pole in the b-space integration. In the framework of the MP, however, the behavior of the corresponding nonperturbative form factor as a function of the vector boson invariant mass has been unknown. In this work, we present a first systematic study of the nonperturbative form factor associated with the resummed form factor in the MP. The matching of the b-space resummation formulas between the MP and the b_* model indicates that the nonperturbative form factor in the MP has the milder dependence on the vector boson invariant mass than that in the b_* model . To clarify this point quantitatively, we perform a global fit of the nonperturbative form factor in the MP resummation at the next-to-leading logarithmic accuracy, with the Z boson production data at the Tevatron and the low energy Drell-Yan data. We obtain good description of the transverse momentum distribution of vector bosons using a gaussian form of the nonperturbative form factor and find the weak dependence of the corresponding nonperturbative parameter on the vector boson invariant mass, which in turn allows an interpretation as arising from the intrinsic transverse momentum of partons inside the proton.Speaker: Prof. Kazuhiro Tanaka (Juntendo University)
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
- 16:00
- 16:20
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16:45
Medium-induced soft gluon radiation in the quark scattering process without color transfer in t-channel 20mWe study coherence effects on the medium-induced soft gluon radiation off an ''asymptotic quark " traversing a hot and dense QCD medium. The transverse momentum spectrum of the emitted gluon is computed at first order in opacity expansion. The interference effects between the initial and final state radiation modify the soft gluon radiation when a finite angle between the initial and final quarks is considered. The spectrum presents a soft divergence. We comment on possible implications on observables in heavy ion collisions which are sensitive to the initial state radiation.Speaker: Hao Ma
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Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
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16:00
Studies of jet shapes and substructure with ATLAS 20mThe internal structure of jets produced in proton-proton collisions at 7 TeV centre-of-mass energy provides a direct test of QCD calculations of gluon and quark radiation, as well as having sensitivity to hadronisation and underlying event. The transverse energy distribution around the jet core has been measured, as well as the fragmentation of a jet into charged particles. Jet shapes - including the jet mass - and jet substructure have the potential to identify jets coming from massive, boosted particles decaying hadronically. Techniques have also been developed for reducing the sensitivity of jet physics to soft QCD and to multiple proton-proton collisions. A selection of such variables is also measured and compared to a range QCD calculations and phenomenological models.Speaker: Adam Robert Davison (University College London (UK))
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16:20
QCD resummation for jet-mass distributions 20mWe study the jet-mass distribution for jets produced in hadron-hadron collision in QCD. In order to obtain reliable phenomenological results we resum to all-order in perturbation theory those contributions coming from collinear and soft gluons. Beyond the leading-logarithmic accuracy the resummation is made more complicated by the presence of non-global logarithms and logarithms related to the choice of the jet-algorithm. We apply our calculation to the interesting case of the jet-mass in Z+jet events, which is of great phenomenological interest for boosted Higgs.Speaker: Simone Marzani (IPPP Durham)
- 16:40
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17:00
Boosted hadronically decaying tops in new physics searches 20mTop momentum reconstruction often plays an important role for new physics signal reconstruction at the LHC. In principle for a hadronically decaying top, it is possible to reconstruct its momentum fully but one suffers from large QCD and combinatorial backgrounds. Starting from geometrically large sizes of jets and looking into their substructure, we can efficiently reduce these background. We develop HEPTopTagger by adopting a combination of the Cambridge/Aachen algorithm and the mass drop criterion. As application for physics cases, we illustrate the scalar top reconstruction and the top forward-backward asymmetry.Speaker: 道久 竹内 (Heidelberg)
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16:00
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Heavy flavours Drawing Room, Mathematical Institute
Drawing Room, Mathematical Institute
University of Bonn
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16:00
Bottomonium(-like) states at Belle 18mThe Belle collaboration recently reported the discovery of the p-wave Bottomonium singlets, hb(1P) and hb(2P), the surprising observation of resonant substructure in Y(5S) --> pi+pi-Y(nS), hb(mP) (n=1-3, m=1,2), and the first observation of the radiative transition hb(1P) --> gamma etab(1S) in 121.4 1/fb of data collected near the Upsilon(5S) resonance at the KEKB asymmetric-energy e^+e^- collider. We report further studies performed at this energy.Speaker: Umberto Tamponi (Torino)
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16:18
Confirmation of a new narrow mass state decaying into Upsilon(1S)gamma 18mUsing the 1.3 fb$^{-1}$ sample of D0 RunII data taken between 2002 and 2006, we observe a new state decaying into $\Upsilon(1S) + \gamma$, where the $\Upsilon(1S)$ is detected by its decay into an oppositely charged muon pair, and the photon is reconstructed by its conversion into an electron-positron pair. The significance of this structure is six standard deviations and its mass is consistent with that of the state recently discovered by the ATLAS Collaboration.Speakers: Claus Buszello (Uppsala University (SE)), Claus Buszello (Department of Physics and Astronomy-University of Uppsala), Claus Buszello (Uppsala University)
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16:36
Bc + b baryons studies at LHCb 18mDuring the year 2011, the LHCb experiment has accumulated 1 fb-1 of data in proton-proton collisions data at 7 TeV, collecting a sample rich in both Bc mesons and b baryons. Studies of these states provide a wealth of new measurements as well as probes of QCD theory predictions. We will present studies of Bc production together with precision measurements of both the mass and lifetime, in Bc->J/psi pi, J/psi mu nu and studies of the Bc-> J/psi 3pi mode. Measurements of the properties of \Xi_b and Omega_b baryons including the mass and studies of excited B hadron states will also be presented.Speaker: Dr Zhenwei Yang (Tsinghua University (CN))
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16:54
Properties and decays of b hadrons at D0 18mMerged abstract: "Analysis of the decay $B_s^0 \rightarrow J/\psi K^+ K^-$ $M(K^+K^-)>1.35$~GeV" "Measurement of the $\Lambda_b$ lifetime in the $\Lambda_b \to J/\psi \Lambda$ exclusive decay channel using the full D0 dataset"Speaker: Enrique Camacho Perez (Centro Invest. Estudios Avanz. IPN (MX))
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17:12
Baryonic B decay results from BABAR 18mDecays of B mesons into final states containing baryons are much less understood than decays into mesons, and are useful for shedding light on baryon-production mechanisms and intermediate states. We report the results of recent and new studies of such decays, including B- -->Sigma_c++ pbar pi- pi-, B0bar -->Lambda_c+ pbar p pbar, and B --> D(*) p pbar (npi). Both the total decay rates and the resonant structure are reported.Speaker: Marcus Ebert (SLAC)
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Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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16:00
Overview on Orbital Angular Momentum 30mIn this talk, we will summarize recent developments on the orbital angular momentum of partons in nucleon, from various observables in high energy processes, including generalized parton distributions, transverse momentum dependent parton distributions, etc.Speaker: Dr Feng Yuan (Lawrence Berkeley National Laboratory)
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16:30
Constraining quark angular momentum with the Sivers function 20mThe determination of quark angular momentum requires the knowledge of the generalized parton distribution E in the forward limit. We assume a connection between this function and the Sivers transverse-momentum distribution, based on model calculations and theoretical considerations. Using this assumption, we show that it is possible to fit at the same time nucleon magnetic moments and semi-inclusive single-spin asymmetries. This imposes additional constraints on the Sivers function and opens a plausible way to quantifying quark angular momentum.Speaker: Alessandro Bacchetta (University of Pavia)
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16:50
Phenomenology of Sivers Effect with TMD Evolution 20mFollowing the TMD evolution scheme recently proposed for the Sivers distribution function, we propose a simple strategy to take into account this TMD Q^2 dependence in our phenomenological extraction of the Sivers function from SIDIS data. New results are presented and possible future applications are discussed.Speaker: Mariaelena Boglione (University of Turin)
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17:10
Transverse Single Spin Asymmetry in ep^\up -> e+J/\psi +X$ 20mWe discuss the possibility of using electroproduction of $J/\psi $ as a probe of gluon Sivers function by measuring single spin asymmetry in experiments with transversely polarized protons and electron beams. We estimate SSA for JLab, HERMES, COMPASS and eRHIC energies using color evaporation model of charmonium production and find asymmetry up to 25 $\%$ for certain choices of model parameters which have been used earlier for estimating SSA in SIDIS and Drell Yan process.Speaker: Dr Asmita Mukherjee (IIT Bombay)
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Departure for Satzvey Castle (bus transfer) 1h 30m Main entrance of Physics Institute
Main entrance of Physics Institute
University of Bonn
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23:00
Medieval banquet 4h Satzvey Castle
Satzvey Castle
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10:10
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Combined: Electroweak and searches/heavy flavours Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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09:00
Top quark pair production beyond NLO 18mI present recent calculations of observables in top quark pair production at hadron colliders, including the total cross section, the invariant mass distribution, the transverse momentum and rapidity distributions, and the forward-backward asymmetry. The calculations are based on the resummation of threshold logarithms at NNLL accuracy beyond NLO.Speaker: Li Lin Yang
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09:18
Measurements of single top quark production at ATLAS 18mWe present the result of a measurement of single top-quark production in the t-channel at 7 TeV proton-proton collisions with the ATLAS detector at the Large Hadron Collider. A lower limit on the CKM matrix element |Vtb| is extracted from this measurement. The single-top quark production in the Wt- and s-channels is also explored.Speakers: William Bell (Unknown), William Hamish Bell (Universite de Geneve (CH))
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09:36
Searches for BSM physics with top quarks at ATLAS 18mMerged abstract: "Searches for new physics effect involving top quarks" "Search for t tbar Resonances in p pbar collisions with the ATLAS detector at LHC"Speakers: Philippe Calfayan (Ludwig-Maximilians-Univ. Muenchen-Unknown-Unknown), Philippe Calfayan (Ludwig-Maximilians-Univ. Muenchen (DE))
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09:54
Searches for physics beyond the standard model with top quarks at CMS 18mSeveral searches of physics beyond the standard model involving top quarks in the final state are presented. These searches encompass top decays in FCNC channels, resonances decaying in ttbar final states, new heavy quarks decaying to top quarks, production of same-sign quarks, and recent tests of various new physics models.Speaker: Victor Eduardo Bazterra (University of Illinois at Chicago (US))
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10:12
Searches for new physics in the top sector at the Tevatron 18mThe kinematic properties of the data used for the measurement of the top-antitop quark pair production and of the single top quark production cross sections are used to set constraints on a variety of signals of physics beyond the SM. We set constraints on possible 4th generation top quarks, on possible resonances that would decay into top-antitop quark pairs, on possible resonances that would decay in top and bottom quark pairs. We also set constraints on possible anomalous couplings at the Wtb vertices. Finally we set limits on possible t-->uZ, cZ decays by studying final states with three charged leptons.Speaker: Yvonne Peters
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Combined: Hadronic final states/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,-
09:00
New features in version 2 of the fastNLO project 20mStandard methods for higher-order pQCD calculations of cross sections in hadron-induced collisions are time-consuming. The fastNLO project uses multi-dimensional interpolation techniques to convert the convolutions of perturbative coefficients with parton distribution functions and the strong coupling into simple products. By integrating the perturbative coefficients for a given observable with interpolation kernels, fastNLO can store the results of the time-consuming calculation in tables which can subsequently be used for very fast calculations of the same observable for arbitrary PDFs, alpha_s, and different scales. These tables and corresponding user codes are currently available for a large number of jet measurements at the LHC, the Fermilab Tevatron, and HERA. fastNLO is currently used in publications of experimental results by the ATLAS, CMS, CDF, D0, and H1 collaborations, and in all recent global PDF analyses by MSTW, CTEQ, and NNPDF. This talk will focus on new developments, implemented in the new version 2 of fastNLO, which enhance and broaden the functionality.Speaker: Daniel Andreas Britzger (DESY)
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09:20
Inclusive jet production measured with ATLAS, and constraints on PDFs 20mInclusive jet and dijet double-differential cross sections have been measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The cross sections were measured using jets clustered with the anti-kT algorithm. The measurements are performed in the jet rapidity range |y|<4.4, covering jet transverse momenta from 20 GeV to 1.5 TeV and dijet invariant masses from 70 GeV to 5 TeV. The data are compared to expectations based on next-to-leading order QCD calculations corrected for non-perturbative effects, as well as to next-to-leading order Monte Carlo predictions. In addition to a test of the theory in a new kinematic regime, the data also provide sensitivity to parton distribution functions in a region where they are currently not well-constrained.Speaker: Dr Bogdan Malaescu (CERN)
- 09:40
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10:00
On the timelike splitting functions at NNLO and beyond 20mWe present the third-order (NNLO) contributions to the timelike splitting functions governing the evolution of parton fragmentation functions in QCD. The hitherto missing quark-gluon and gluon-quark quantities have been derived by studying physical evolution kernels for photon- and Higgs-exchange DIS structure functions and their counterparts in semi-inclusive annihilation, together with constraints from the momentum sum rule and supersymmetric limit. A numerically tolerable uncertainty remains in the quark-gluon case which does not affect the endpoint logarithms for small and large momentum fractions x. The stability of the perturbative expansion at small x is spoiled by large double logarithms up to alpha_s^n ln^{2*n-2} x. Much more stable results are obtained when the fixed-order results are combined with the new small-x resummation up to the next-to-next-to-leading (NNL) logarithms (the derivation of which is discussed in another contribution).Speaker: Andreas Vogt (University of Liverpool)
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10:20
A new approach to hadron multiplicity ratio 20mWe present a new approach in considering and including the perturbative and non-perturbative contributions to the gluon-quark multiplicity ratio. The new method is motivated by new developments in timelike small x resummation and exploit the recently computed NNLO timelike splitting fnctions. Comparison of our new results with other methods and with data will also be presented.Speaker: Paolo Bolzoni (DESY)
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Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
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09:00
The NLO jet vertex for Mueller-Navelet and forward jets in the small-cone approximation 20mWe calculate in the next-to-leading order the impact factor (vertex) for the production of a forward high-p_T jet, in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. The final expression for the vertex turns out to be simple and easy to implement in numerical calculations.Speaker: Prof. Alessandro Papa (University of Calabria and INFN Cosenza (Italy))
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09:20
The non-forward BFKL equation, infrared effects and hard diffraction 20mAn iterative solution best suited for a Monte Carlo implementation for the non-forward BFKL equation is presented and possible applications discussed. We introduce running coupling effects in a way compatible with the bootstrap, fundamental condition for gluon reggeization and see how this naturally leads to renormalon effects in the infrared.Speaker: Clara Salas (IFT)
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09:40
Diffraction and rapidity gap measurements with ATLAS 20mTransverse energy distributions and regions of low activity in proton-proton scattering events are sensitive to soft physics, low x and diffractive processes, and have been measured in inclusive "minimum bias" scatters as well as in dijet events at sqrt(s) = 7 TeV. In the inclusive analysis, cross sections are measured differentially in terms of Delta eta F, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, in which no final state particles are produced above a transverse momentum threshold p_T Cut. The measurements span the region 0 < Delta eta F < 8 for 200 < p_T Cut < 800 MeV. The data are used to constrain the value of the pomeron intercept appropriate to triple Regge models of soft diffraction, and the cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements. The dijet measurements study jet activity in the rapidity interval bounded by a dijet system, as well as in the forward region. Differential distributions are compared to various QCD calculations including different approximations for gluon radiation.Speaker: Pavel Ruzicka (Acad. of Sciences of the Czech Rep. (CZ))
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Future of DIS Seminar room, Bethe Centre for Theoretical Physics
Seminar room, Bethe Centre for Theoretical Physics
University of Bonn
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- 09:35
- 10:05
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10:30
Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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09:20
Timelike Compton Scattering - new theoretical results and experimental possibilities 30mGeneralized Parton Distributions (GPDs) offer a new way to access the quark and gluon nucleon structure. We advocate the need to supplement the experimental study of deeply virtual Compton scattering by its crossed version, timelike Compton scattering (TCS) i.e. the exclusive photoproduction of a lepton pairs with large invariant mass. We review recent progress in this domain, in particular the need to include NLO corrections to any phenomenological program to extract GPDs from experimental data. We also stress that data on TCS at high energy should be available soon thanks to the proposed experimental program at JLab at 12 GeV, and study of ultraperipheral collisions at RHIC and LHC which opens a window on quark and gluon GPDs at very small skewness.Speaker: Jakub Wagner (National Center for Nuclear Research)
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09:50
Conformal symmetry and the relations between perturbative contributions to the Bjorken and Ellis-Jaffe sum rule of the polarized DIS 20mUsing operator-product expansion approach for the triangle diagram of Axial-Vector-Vector currents symmetry I derive the singlet variant of the Crewther relation, which is valid in the conformal -invariant limit of perturbative approach. I demonstrate that in the conformal-invariant limit of U(1)-model the non-singlet coefficient function of Bjorken and Ellis-Jaffe sum rule identically coincide with the coefficient function of singlet contribution to Ellis-Jaffe sum rules in all orders of perturbation theory. The discussions of the possible generalizations to the conformal-invariant limit of SU(N_c) theory is presented.Speaker: A. L. Kataev (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia)
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10:10
Distribution of linearly polarized gluons inside a large nucleus 20mI will discuss the color glass condensate (CGC) based calculation of two gluon TMDs inside a large nucleus at small x. The main focus is on the linearly polarized gluon TMD which is often referred to as the gluon Boer-Mulders function. With the derived gluon TMDs at small x, it is shown that an effective TMD factorization can be established at small x in a certain kinematical region. As a result, this distribution, in principle, can be accessed through measuring $\cos 2 \phi$ azimuthal asymmetries in various hard scattering processes, such as di-jets production in SIDIS, virtual photon-jet production in pA collisions and heavy quark pair production in pA collisions.Speaker: Dr jian zhou (Regensburg University)
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09:20
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10:40
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11:00
Coffee break 20m
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11:00
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12:40
Combined: Electroweak and searches/heavy flavours Lecture Hall 1, Physics Institute
Lecture Hall 1, Physics Institute
University of Bonn
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11:00
Hunting New Physics in Top Pair Production 18mFollowing recent intriguing experimental results on top quark pair production from the Tevatron I review the present status of new physics explanations put forward to explain the experimental observations deviating from standard model predictions. All proposals face severe constraints from precisely measured flavor, electroweak and high pt collider observables. Possible future measurements at the LHC able to discern among the various proposals are also discussed.Speaker: Jernej Kamenik (Jozef Stefan Institute)
- 11:18
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11:36
Searches for BSM physics using flavour transitions at the Tevatron 18mWe report recent results from indirect searches for BSM physics using flavor processes in the whole sample of 9.6 fb^-1 collected by CDF in Tevatron Run II. These include the final measurements of flavor-changing-neutral-current, rare B-> mu^+ mu^- and B-> K mu^+ mu^- decays, the final measurements of the bottom-strange mixing phase (phi_s) using Bs->J/Psi Phi decays, measurements of the branching fractions of Bs --> Ds(*)+Ds(*)- that help constrain DeltaGamma_s, and searches for charge-parity violation in charm decays. D0 results will also be presented.Speaker: Lucia Grillo
- 11:54
- 12:12
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11:00
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11:00
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12:40
Combined: Future of DIS/structure functions Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,- 11:00
- 11:40
- 12:10
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11:00
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12:40
Diffraction and vector mesons Lecture Hall, Institute for Applied Physics
Lecture Hall, Institute for Applied Physics
University of Bonn
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11:00
Calculation of the Two-Loop Gluon Regge Trajectory from Lipatov's Effective Action 20mLipatov's high-energy effective action is a very promising tool for computations in the Regge limit beyond leading order. Its use has been however restricted to tree-level calculations for many years. Recently a regularization/subtraction prescription was proposed that allows to extend the formalism to deal with loops in a consistent way. We illustrate the procedure with the computation of the gluon Regge trajectory at two loops.Speaker: José Daniel Madrigal (IFT UAM/CSIC, Madrid)
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11:20
Single-pion production in neutrino-matter collisions 20mIn this talk we present the results of the diffractive single-pion production on the protons and nuclei (both for the coherent and incoherent cases). We demonstrate that all the evaluations which are based on Adler relation (AR) are valid only in the region up to 10 GeV, in the regime of short lifetime of heavy hadronic fluctuations. At higher energies, when all the relevant time scales considerably exceed the size of the target, the AR explicitly breaks down on an absorptive target, such as a heavy nucleus. In this regime, close to the black disc limit, the off-diagonal diffractive amplitudes vanish, while the diagonal one, \pi->\pi, which enters the AR, maximizes and saturates the unitarity bound.Speaker: Dr Marat Siddikov (UTFSM)
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11:40
Diffractive Vector Meson Cross Sections from BK evolution with Impact Parameter 20mIn previous numerical work the solution to the BK evolution equation with impact parameter dependence was calculated with modeled confinement effects. This solution is used to calculate diffractive cross sections for the vector mesons J/Psi, Rho, and Phi. In order to bring the numerical results into agreement with HERA data modification to the photon wavefunction is necessary. This correction is discussed as well as effects on the ability to describe the F2 structure function data.Speaker: Dr Jeffrey Berger (Penn State University (USA))
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12:00
Nonlinear equation for coherent gluon emission 20mMotivated by the regime of QCD explored nowadays at LHC where both the total energy of collision and momenta transfers are high, evolution equations of high energy factorization are investigated. Briefly we overview results obtained so far for proton proton collisions within high energy factorization approach for jet related observables and we give some predictions for proton lead. This results motivate us to study such effects like parton saturation in final states where one is inevitably led to investigate how to combine physics of the BK and CCFM evolution equations. As a result of this study new equations are obtained. A new exclusive form of the BK equation is presented and also an extension of the CCFM equation to account for nonlinearity.Speaker: Dr Krzysztof Kutak (Instytut Fizyki Jadrowej Polskiej Akademii Nauk)
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12:20
A comparative study of small x Monte Carlos with and without QCD coherence effects 20mWe compare two Monte Carlo implementations of resummation schemes for the description of parton evolution at small values of Bjorken x. One of them if based on the BFKL evolution equation. The other one is based on the CCFM partonic kernel where QCD coherence effects are introduced. It has been argued that both approaches agree with each other in the x to 0 limit. We show that this is not the case for azimuthal angle dependent quantities since at high energies the BFKL approach is dominated by its zero conformal spin component while the CCFM gluon Green function receives contributions from all conformal spins even at very small x.Speaker: Dr Michal Deak (Universidade de Santiago de Compostela)
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11:00
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11:00
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12:40
Hadronic final states Small Lecture Hall, Mathematical Institute
Small Lecture Hall, Mathematical Institute
University of Bonn
- 11:00
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11:20
Minimum bias and underlying event studies 20mThe majority of proton-proton collisions at the LHC contain only soft, low transverse-momentum scatters. Such scatters also occur between the remnants of the protons in conjunction with short-distance, high momentum scatters. Measurements of soft particle production and energy flow are presented fir a wide range of different kinematic selections; correlations between the produced particles, and identified strange particles, are also studied. The energy flow and charged-particle distributions accompanying hard scatters are also measured. The measurements are compared to current Monte Carlo simulations and used to tune the parameters and suggest improved physics models.Speaker: Dr Arthur Moraes (University of Glasgow (GB))
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11:40
Measurement of the forward energy flow in pp collisions at sqrt{s}=7 TeV with the LHCb experiment 20mWe present the results on the energy flow measured with minimum-bias data collected by the LHCb experiment in $pp$ collisions at $\sqrt{s}=7$~TeV for inclusive minimum bias interactions, hard scattering processes and events with enhanced or suppressed fractions of diffractive contributions. The measurements are performed in the pseudorapidity range $2<\eta<5$ which corresponds to the main detector acceptance of the LHCb spectrometer. The results of the measurements are compared to predictions given by several Monte Carlo event generators, which model the underlying event activity in different ways.Speaker: Dmytro Volyanskyy (Max-Planck-Gesellschaft (DE))
- 12:00
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12:20
The Underlying Event in Herwig++ 20mWe review the modelling of multiple interactions in the event generator Herwig++ and study implications of recent tuning efforts to Tevatron and LHC data. A crucial ingredient to a successful description of minimum bias and underlying event observables is a model for colour reconnection. Improvements to this model inspired by statistical physics are presented.Speaker: Christian Roehr (K)
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11:00
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12:40
Spin physics Lecture Hall, Institute for Physical Chemistry
Lecture Hall, Institute for Physical Chemistry
University of Bonn
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11:00
Linearly Polarized Gluons and the Higgs Transverse Momentum Distribution 20mWe investigate the possible role of linearly polarized gluons in Higgs production from unpolarized pp collisions. The angular independent transverse momentum distribution of the produced Higgs boson is found to exhibit a modulation (max 30%) with respect to the naive, unpolarized expectation, with the sign depending on the CP nature of the Higgs boson. The transverse momentum distribution of a scalar Higgs will, therefore, have a shape clearly different from a pseudo-scalar Higgs. We suggest that this effect can be used to determine the parity of the Higgs at the LHC, without the need to use challenging angular distributions of final state particles.Speaker: Mr Wilco den Dunnen (VU University Amsterdam)
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11:20
COMPASS results on transverse spin asymmetries in two-hadron production in SIDIS 20mFor each quark flavour three independent parton distribution functions (PDF) are necessary to describe the nucleon at twist-two level, the quark distribution f1(x), the helicity distribution g1(x) and the transversity distribution h1(x). The transversity distribution function is chiral-odd and therefore is not accessible in deep inelastic scattering (DIS). However, h1(x) can be observed in semi-inclusive DIS in combination with another chirally odd function like the two-hadron interference fragmentation function (IFF) in two-hadron production, which is the subject of this contribution. The 160 GeV/c polarized µ+ beam of CERN's M2 beamline allows COMPASS to investigate the spin structure of the nucleon using polarized solid state targets. After taking the first data on a transversely polarized proton target NH3 in 2007, a full year of data taking followed in 2010 to increase precision. In this contribution the latest results from the 2010 data for the azimuthal asymmetries in two-hadron production are presented, as well as the corresponding results on a polarized deuteron target 6LiD from the data taken in the years 2002-2004. An extraction of h1(x) via a coupling to the two-hadron IFF has been carried out for the 2007 data.Speaker: Christopher Braun (Friedrich-Alexander-Univ. Erlangen (DE))
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11:40
Interference Fragmentation Functions and Transverse Spin Studies. 20mWe report on the first extraction of interference fragmentation functions from the semi-inclusive production of two hadron pairs in back-to-back jets in $e^+e^-$ annihilation. A nonzero asymmetry in the correlation of azimuthal orientations of opposite $\pi^+\pi^-$ pairs is related to the transverse polarization of fragmenting quarks through a significant polarized dihadron fragmentation function. A combined analysis of this asymmetry and the spin asymmetry in the SIDIS process $ep^{\uparrow}\to e'(\pi^+\pi^-)X$ has led to the first extraction of the transversity parton distribution function in the framework of collinear factorization. This result is presented as well.Speaker: Aurore Courtoy (IFPA, AGO Dpt., Universite de Liege)
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12:00
Cross Section for High-$p_T$ Hadron Production in Muon-Deuteron Scattering at $\sqrt{s} = 17.4$\,GeV 20mLepton-nucleon scattering experiments are performed to investigate the (spin-)structure of nucleons. The theoretical framework for the interpretation of such measurements is perturbative QCD (pQCD). In this contribution we present the measurement of the cross section for the quasi-real photoproduction of charged hadrons with high transverse momenta in muon-deuteron scattering at COMPASS ($\sqrt{s} = 17.4$\,GeV). Furthermore, the dependence of the cross section on pseudo-rapidity and the hadron charge is discussed. The results are compared to recent next-to-leading (NLO) pQCD calculations to evaluate the applicability of pQCD to this process at COMPASS energies.Speaker: Christian Hoeppner (Technische Universitaet Muenchen (DE))
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12:20
Soft-gluon resummation for high-pT hadrons at COMPASS 20mWe consider the cross section for the photoproduction reaction gamma + p -> h+ X in fixed-target scattering at COMPASS, where the hadron is produced at large transverse momentum. We investigate the role played by higher-order corrections to the cross section. In particular we adress large logarithmic ``threshold'' corrections to the partonic cross sections, which we resum to all orders.Speaker: Mrs Melanie Pfeuffer (University of Regensburg)
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11:00
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12:40
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14:00
Lunch break 1h 20m Mensa Poppelsdorf
Mensa Poppelsdorf
University of Bonn
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14:00
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18:00
Excursions 4h
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09:00
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10:30
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09:00
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10:20
Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Katerina Lipka (Deutsches Elektronen-Synchrotron (DE))- 09:00
- 09:40
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10:20
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10:50
Coffee break 30m Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany, -
10:50
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12:10
Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Cristinel Diaconu (Universite d'Aix - Marseille II (FR))- 10:50
- 11:30
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12:10
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13:30
Lunch break 1h 20m Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
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13:30
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14:50
Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Hannes Jung (Deutsches Elektronen-Synchrotron (DE))- 13:30
- 14:10
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14:50
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15:20
Coffee break 30m Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany, -
15:20
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17:00
Plenary Wolfgang Paul Lecture Hall
Wolfgang Paul Lecture Hall
University of Bonn
Kreuzbergweg 28, 53115 Bonn, Germany,Convener: Friedrich Klein (Physikalisches Institut)- 15:20
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- 16:40
- 16:50
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