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36. Combined inclusive diffractive cross sections measured with forward proton spectrometers at HERAValentina Sola (Universita e INFN (IT))27/03/2012, 09:00Diffraction and vector mesonsA 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...Go to contribution page
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David Salek (CERN)27/03/2012, 09:20Diffraction and vector mesonsFirst 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...Go to contribution page
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Emmanuel Sauvan (LAPP (IN2P3/CNRS))27/03/2012, 09:40Diffraction and vector mesonsMeasurements 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 โ 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...Go to contribution page
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Richard Polifka (University of Toronto (CA))27/03/2012, 10:00Diffraction and vector mesonsThe 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...Go to contribution page
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Federico Alberto Ceccopieri (Fondazione Angelo Della Riccia Ente Morale)27/03/2012, 11:00Diffraction and vector mesonsA 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.Go to contribution page
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Mrs Sara Taheri Monfared (Semnan university and IPM)27/03/2012, 11:20Diffraction and vector mesonsWe 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 โFixed Flavour Number Schemeโ (FFNS). Having...Go to contribution page
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Mariusz Sadzikowski (Jagiellonian University)27/03/2012, 11:40Diffraction and vector mesonsHERA 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...Go to contribution page
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Leszek Motyka (Jagellonian Univerisity)27/03/2012, 12:00Diffraction and vector mesonsWe 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...Go to contribution page
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Dr Erik Brรผcken (Helsinki Institute of Physics (FI))27/03/2012, 14:00Diffraction and vector mesonsWe 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 ฮณฮณ production in pp ฬ collisions at โs = 1.96 TeV at the Tevatron. In particular, starting from earlier studies by the CDF collaboration, we discuss exclusive dijet, dilepton, Z, J/ฮจ and ฯc productions and finally...Go to contribution page
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Dermot Moran (Univ Manchester)27/03/2012, 14:20Diffraction and vector mesonsWe 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. psiโ and chi_c states, obtained with data...Go to contribution page
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Wenbo Li (Peking University (CN))27/03/2012, 14:40Diffraction and vector mesonsWe 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...Go to contribution page
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Dr Marek Tasevsky (Acad. of Sciences of the Czech Rep. (CZ))27/03/2012, 15:00Diffraction and vector mesonsWe 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...Go to contribution page
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Adrien Besse (L)27/03/2012, 15:20Diffraction and vector mesonsExclusive 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...Go to contribution page
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Emilien Chapon (Centre d'Etudes de Saclay (CEN Saclay)-Unknown-Unknown)27/03/2012, 15:40Diffraction and vector mesonsWe 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...Go to contribution page
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Antonio Vilela Pereira (Universita e INFN (IT))27/03/2012, 16:50Diffraction and vector mesonsThe talk will present CMS measurements on diffractive W and dijet production in p-p collisions at 0.9, 2.36 and 7 TeV.Go to contribution page
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Dr Mickey Chiu (Brookhaven National Lab)27/03/2012, 17:10Diffraction and vector mesonsOne 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...Go to contribution page
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Prof. Antoni Szczurek (Institute of Nuclear Physics Krakow (Poland))27/03/2012, 17:30Diffraction and vector mesonsWe 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....Go to contribution page
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Jacek Ciborowski (University of Warsaw)28/03/2012, 16:00Diffraction and vector mesonsThe 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...Go to contribution page
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Dr Justyna Tomaszewska (DESY)28/03/2012, 16:20Diffraction and vector mesonsThe 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...Go to contribution page
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Prof. Ruben Sandapen (University of Moncton (Canada))28/03/2012, 16:40Diffraction and vector mesonsWe 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...Go to contribution page
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Prof. Kazuhiro Tanaka (Juntendo University)28/03/2012, 17:00Diffraction and vector mesonsIn the conventional b_* model for the CollinsโSoperโSterman 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...Go to contribution page
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Prof. Alessandro Papa (University of Calabria and INFN Cosenza (Italy))29/03/2012, 09:00Diffraction and vector mesonsWe 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.Go to contribution page
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Clara Salas (IFT)29/03/2012, 09:20Diffraction and vector mesonsAn 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.Go to contribution page
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Pavel Ruzicka (Acad. of Sciences of the Czech Rep. (CZ))29/03/2012, 09:40Diffraction and vector mesonsTransverse 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...Go to contribution page
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Josรฉ Daniel Madrigal (IFT UAM/CSIC, Madrid)29/03/2012, 11:00Diffraction and vector mesonsLipatov'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...Go to contribution page
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Dr Marat Siddikov (UTFSM)29/03/2012, 11:20Diffraction and vector mesonsIn 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...Go to contribution page
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Dr Jeffrey Berger (Penn State University (USA))29/03/2012, 11:40Diffraction and vector mesonsIn 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...Go to contribution page
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Dr Krzysztof Kutak (Instytut Fizyki Jadrowej Polskiej Akademii Nauk)29/03/2012, 12:00Diffraction and vector mesonsMotivated 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...Go to contribution page
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Dr Michal Deak (Universidade de Santiago de Compostela)29/03/2012, 12:20Diffraction and vector mesonsWe 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...Go to contribution page
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