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Friederike Januschek (DESY)27/03/2012, 09:00Structure functionsThe 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...Go to contribution page
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Stefan Schmitt (Ruprecht-Karls-Universitaet Heidelberg (DE))27/03/2012, 09:20Structure functionsAt 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...Go to contribution page
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Uta Klein (University of Liverpool (GB))27/03/2012, 09:40Structure functionsMerged 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"Go to contribution page
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Krzysztof Nowak (Deutsches Elektronen-Synchrotron (DE))27/03/2012, 10:10Structure functionsA 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...Go to contribution page
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Dr maria ubiali (University of Edinburgh)27/03/2012, 11:00Structure functionsA 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...Go to contribution page
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Sergey Alekhin27/03/2012, 11:25Structure functionsWe 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...Go to contribution page
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Pedro Jimenez-Delgado (Jefferson Lab)27/03/2012, 11:50Structure functionsDifferent 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.Go to contribution page
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290. Uncertainties in Determining Parton Distributions at Large x: Results from the CJ CollaborationCynthia Keppel (Hampton University)27/03/2012, 12:15Structure functionsThe 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...Go to contribution page
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Johannes Bluemlein (DESY)27/03/2012, 12:35Structure functionsWe 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 $g_2(x,Q2)$.Go to contribution page
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Pavel Nadolsky (Southern Methodist University)27/03/2012, 14:00Structure functionsI 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.Go to contribution page
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Rodolfo Sassot (Universidad de Buenos Aires)27/03/2012, 14:25Structure functionsWe 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...Go to contribution page
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Karol Kovarik (University of Karlsruhe)27/03/2012, 14:45Structure functionsA 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 โA 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...Go to contribution page
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Clara Salas (IFT, Madrid)27/03/2012, 15:05Structure functionsThe 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...Go to contribution page
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Hannes Jung (Deutsches Elektronen-Synchrotron (DE))27/03/2012, 15:25Structure functionsWe 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...Go to contribution page
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Giovanni Antonio Chirilli (Lawrence Berkeley National Laboratory (LBNL))27/03/2012, 16:30Structure functionsI 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.Go to contribution page
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Prof. Otto Nachtmann (Institute for Theoretical Physics, University of Heidelberg)27/03/2012, 16:45Structure functionsThe 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...Go to contribution page
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Carlo Ewerz (ExtreMe Matter Institute EMMI, GSI, and Heidelberg University)27/03/2012, 17:00Structure functionsFrom 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...Go to contribution page
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Krzysztof Kutak (I)27/03/2012, 17:20Structure functionsMotivated 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...Go to contribution page
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Franco Buccella (Unknown)27/03/2012, 17:35Structure functionsFirst 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...Go to contribution page
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David d'Enterria (CERN)28/03/2012, 11:30Structure functionsThe 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...Go to contribution page
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Voica Ana Maria Radescu (Deutsches Elektronen-Synchrotron (DE))28/03/2012, 11:50Structure functionsHERAFitter, 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...Go to contribution page
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