Stefan Prestel
(Deutsches Elektronen-Synchrotron (DE))
28/04/2015, 08:30
WG4 QCD and Hadronic Final States
This contribution reviews recent developments in matching higher-order perturbative QCD calculations to parton-shower event generators.
Tony Kwan
(University of Victoria (CA))
28/04/2015, 08:55
WG4 QCD and Hadronic Final States
The ATLAS Collaboration has performed precision measurements
of the transverse momentum of the Z/gamma* boson and the angular
correlations of the DrellโYan lepton pairs with the phi* observable,
in different di-lepton invariant mass and rapidity regions. These
measurements are sensitive to soft resummation effects and hard jet
emissions for small and large momentum transfers,...
Harikrishnan Ramani
(Yang Institute Of Theoretical Physics)
28/04/2015, 09:45
WG4 QCD and Hadronic Final States
The WW production cross-section measured at the LHC has been consistently exhibiting a mild excess beyond the SM prediction leading to speculations that new physics could be hiding in these measurements. In this talk, I discuss a possible explanation of the excess in terms of large logarithms that arise from a jet-veto condition that is imposed in the experimental analyses to reduce...
Sanshiro Mizuno
(University of Tsukuba (JP))
29/04/2015, 08:30
WG4 QCD and Hadronic Final States
Direct photons are very interesting probes because they are not modified once created and emitted during all stages of the collisions.
Especially soft photons have been actively measured to study the hot and dense medium (QGP) created in high energy heavy ion collisions.
It is expected that direct photons have different angular emission patterns depending on their production...
Petr Balek
(Charles University (CZ))
29/04/2015, 08:50
WG4 QCD and Hadronic Final States
Recent results on electroweak probes in lead-lead and
proton-lead collisions from the ATLAS Detector at the LHC
Abstract: Photons and weak bosons do not interact strongly with the
dense and hot medium formed in the nuclei collisions, thus should be
sensitive to the nuclear modification of parton distribution functions
(nPDFs). In particular, proton-lead collisions provide an...
Ivan Sykora
(Comenius University (SK))
29/04/2015, 09:10
WG4 QCD and Hadronic Final States
Bose-Einstein correlations provide a unique opportunity for
detailed understanding of the space-time geometry of the hadronization
region, for determining the size and shape of the source from which
particles are emitted and for interpreting of quark confinement
effects. Bose-Einstein correlation lead to an enhancement of the
production of identical bosons close in phase space. The...
Sandra Padula
(UNESP - Universidade Estadual Paulista (BR))
29/04/2015, 09:30
WG4 QCD and Hadronic Final States
Two-particle, quantum-statistical (Bose-Einstein) correlations are measured with the CMS experiment in pp collisions at 0.9, 2.76 and 7 TeV center-of-mass energies, as well as in pPb and peripheral PbPb collisions, respectively at 5.02 and 2.76 TeV center-of-mass energy per nucleon. The analysis is performed as a function of both the charged particle multiplicity and the average transverse...
Soumya Mohapatra
(State University of New York (US))
29/04/2015, 09:50
WG4 QCD and Hadronic Final States
Measurements of soft particle production have provided
valuable insight on properties of the evolution of the quark-gluon
plasma in Pb+Pb collisions at the LHC. In particular, measurements of
flow harmonics using the azimuthal angle distributions of low-pT
particles directly test hydrodynamic model descriptions of its
evolution. The large acceptance of the ATLAS detector enables...
Paolo Gunnellini
(Deutsches Elektronen-Synchrotron (DE))
29/04/2015, 10:45
WG4 QCD and Hadronic Final States
A measurement of the underlying event activity in pp collisions is performed using events with a leading charged particle jet produced at central pseudorapidities and of transverse momentum in the range of 1 to 100 GeV. The underlying event activity is measured independently in the two halves of the transverse region with the maximum as well as minimum activities. The results obtained from pp...
Claire Gwenlan
(University of Oxford (GB))
29/04/2015, 11:10
WG4 QCD and Hadronic Final States
The measurement of production properties of mesons and
baryons at sqrt(s)=7 TeV using pp collision data collected with the
ATLAS experiment is presented and compared to predictions. Particle
distributions sensitive to the underlying event in proton-proton
collisions have also been measured with the ATLAS detector at the LHC
at 7 TeV centre-of-mass energy. Various and complementary...
You-Hao Chang
(National Taiwan University (TW))
29/04/2015, 11:35
WG4 QCD and Hadronic Final States
Double parton scattering is measured in different channels using the CMS experiment at the CERN LHC. Data from pp collisions collected at 7 and 8 TeV center-of-mass energy are used. Several final states are investigated to identify and measure the signature of double parton scattering in inelastic events. Parameters are extracted from the data that are suited in an optimal way to distinguish...
Giovanni Ossola
(City University of New York (US))
29/04/2015, 14:00
WG4 QCD and Hadronic Final States
This talk will focus on the automation of higher-order QCD calculations.
Alex Baudouin E Van Spilbeeck
(Universiteit Antwerpen Physics Department)
29/04/2015, 14:25
WG4 QCD and Hadronic Final States
Several measurements of QCD jets are presented as performed at different center-of-mass energies with the CMS experiment. By extending the measurement into the forward phase space and also towards low-pT the sensitivity to new features of QCD is maximised. The simultaneous observation of several jets in the same event is exploited to study for example the angular correlations of Mueller...
Tomas Jezo
(Milano Bicocca)
29/04/2015, 14:50
WG4 QCD and Hadronic Final States
We discuss the subject of matching the NLO QCD corrections to the parton shower for processes mediated by coloured resonances. In order to perform precise realistic simulations of the production of resonances their decay must be included. In current frameworks for NLO+PS simulations, however, problems arise when generating the radiation from the decay of the resonance, especially for narrow...
Matthias Saimpert
(CEA/IRFU,Centre d'etude de Saclay Gif-sur-Yvette (FR))
29/04/2015, 16:15
WG4 QCD and Hadronic Final States
Measurements of the inclusive photon production performed by
the ATLAS collaboration are reported in different fiducial regions
covering a wide acceptance. Comparisons to the data of next-to-leading
order QCD calculations MCFM and JetPhox with different PDFs are
presented. The theoretical uncertainties, including scale, strong
coupling, and PDF uncertainties are evaluated. The cross...
Enrico Bothmann
(II. Physikalisches Institut, Universitaet Goettingen)
29/04/2015, 16:40
WG4 QCD and Hadronic Final States
The determination of theoretical error estimates and PDF/$\alpha_s$-fits require
fast evaluations of differential cross sections for varied QCD input parameters.
These include PDFs, the strong coupling constant $\alpha_S$
and the renormalization and factorization scales.
Beyond leading order QCD, a full dedicated calculation for each set of parameters
is often too time-consuming,...
Dr
Mirko Serino
(Institute of Nuclear Physics, PAN, Cracow)
29/04/2015, 17:05
WG4 QCD and Hadronic Final States
We use an extension of the Britto-Cachazo-Feng-Witten (BCFW) recursion relation to evaluate analytically tree-level 5-point matrix elements of two fermions and three gluons with one of the partons off the mass-shell, while preserving gauge invariance.
These amplitudes find their domain of application within the high-energy factorisation (or TMD-factorisation) framework, which requires...
Aditi Mukhopadhyay
(urn:Google)
29/04/2015, 17:30
WG4 QCD and Hadronic Final States
We present the current status of the comparisons with the respective data of the predictions of our approach of exact amplitude-based resummation in quantum field theory as applied to precision QCD calculations as needed for LHC physics. The agreement between the theoretical predictions and the data exhibited continues to be encouraging.
Feng Yuan
(LBNL)
30/04/2015, 08:30
WG4 QCD and Hadronic Final States
In this talk, we will present our recent theoretical calculations of all order soft gluon resummation for dijet azimuthal angular correlations at the hadron colliders. The relevant coefficients for the Sudakov resummation factor, the soft and hard factors, are calculated. The theory predictions agree well with the experimental data from D0 Collaboration at the Tevatron, ATLAS and CMS...
Leonard Apanasevich
(University of Illinois at Chicago (US))
30/04/2015, 08:55
WG4 QCD and Hadronic Final States
We present recent jets results from CMS at a centre of mass energy of 7 and 8 TeV. The impact of those data on the precise measurement of the QCD parameters is studied.
Camille Belanger-Champagne
(McGill University (CA))
30/04/2015, 09:20
WG4 QCD and Hadronic Final States
The measurements of the production cross sections of inclusive, di- and tri-jet events probe the dynamics of QCD and can constrain the parton proton structure. Double-differential cross sections are measured and compared to expectations based on next-to-leading order QCD calculations as well as to next-to-leading order Monte Carlo simulations. The study of di-jet systems with a veto on...
Ringaile Placakyte
(Deutsches Elektronen-Synchrotron (DE))
30/04/2015, 09:45
WG4 QCD and Hadronic Final States
Inclusive jet, dijet and trijet differential cross sections are measured in neutral current deep-inelastic scattering for exchanged boson virtualities 150 < Q^2 < 15000 GeV^2 using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of 351 pb^{-1}. Double differential Jet cross sections are obtained using a regularised unfolding...
Daekyoung Kang
(LANL)
30/04/2015, 10:45
WG4 QCD and Hadronic Final States
Event shapes provide a key method of measuring jets in DIS. This was done successfully by H1 and ZEUS and compared with theoretical calculations with next-to-leading-logarithmic (NLL) resummation.
We will present a high precision calculation of a event shape called DIS thrust, with next-to-next-to-next-to-leading-logarithmic resummation and a rigorous treatment of hadronization corrections....
Dr
Yazid Delenda
(Universitรฉ Hadj Lakhdar - Batna)
30/04/2015, 11:10
WG4 QCD and Hadronic Final States
We calculate non-global logarithms at finite $N_c$ for the hemisphere mass distribution in $e^+e^-\to q \bar{q}$ at single logarithmic accuracy up to fifth order in the coupling constant. Our results indicate the possibility of resummation of these logarithms to all orders into an exponential form. We compare our findings to those reported in the literature at large $N_c$ and find agreement....
Dr
Kamel Khelifa-Kerfa
(Universitรฉ Hassiba Benbouali de Chlef)
30/04/2015, 11:35
WG4 QCD and Hadronic Final States
We present a general formalism for computing the matrix-elements squared for the emission of soft energy-ordered gluons to (theoretically) any order in perturbation theory at finite $N_c$. Our formalism is valid in the eikonal approximation. A Mathematica package is being developed for the automated calculation of all real/virtual eikonal squared-amplitudes necessary at a given order. For the...
Heather Turmeau Mcaslan
(University of Sussex (GB))
30/04/2015, 12:00
WG4 QCD and Hadronic Final States
Event shape observables are essential tools for studying the behaviour of high energy QCD. Yet in the region where soft and collinear gluon emission is most dominant, standard perturbation theory is rendered unreliable and the series must be resummed to all orders in the strong coupling. We have recently developed a general method for the resummation of event shapes, in e+e- annihilation, at...
