Conveners
WG1: Structure Functions and Parton Densities
- Richard David Ball (Edinburgh University)
- Vladimir Chekelian (MPI fuer Physik)
- Karol Kovarik
WG1: Structure Functions and Parton Densities
- Richard David Ball (Edinburgh University)
- Vladimir Chekelian (MPI fuer Physik)
- Karol Kovarik
WG1: Structure Functions and Parton Densities
- Karol Kovarik
- Richard David Ball (Edinburgh University)
- Vladimir Chekelian (MPI fuer Physik)
WG1: Structure Functions and Parton Densities
- Karol Kovarik
- Richard David Ball (Edinburgh University)
- Vladimir Chekelian (MPI fuer Physik)
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Julia Grebenyuk (DESY)29/04/2014, 08:30WG1: Structure Functions and Parton DensitiesOral presentationThe reduced cross sections for $e^{+}p$ deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, $318$, $251$ and $225$ GeV. The cross sections, measured double differentially in Bjorken $x$ and the virtuality, $Q^2$, were obtained in the region $0.13\ \leq\ y\ \leq\ 0.75$ and $5\ \leq\ Q^2\ \leq\ 110$ GeV$^2$, where $y$...Go to contribution page
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Stanislav Shushkevich (Deutsches Elektronen-Synchrotron (DE))29/04/2014, 08:53WG1: Structure Functions and Parton DensitiesOral presentationInclusive ep double differential cross sections for neutral current deep inelastic scattering are measured with the H1 detector at HERA. The data were taken with a lepton beam energy of 27.6 GeV and two proton beam energies of Ep = 460 and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of 6.5x10^-4 โคx โค0.65 for...Go to contribution page
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Aharon Levy (Tel Aviv University (IL))29/04/2014, 09:16WG1: Structure Functions and Parton DensitiesOral presentationThe neutral current $e^\pm p$ cross section has been measured up to values of Bjorken $x\cong 1$ with the ZEUS detector at HERA using an integrated luminosity of 187 ${\rm pb}^{-1}$ of $e^-p$ and 142 ${\rm pb}^{-1}$ of $e^+p$ collisions at $\surd s = 318$ GeV. Differential cross sections in $x$ and $Q^2$, the exchanged boson virtuality, are presented for $Q^2 \geq 725$ GeV$^2$. An improved...Go to contribution page
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Oleksii Turkot (DESY)29/04/2014, 09:40WG1: Structure Functions and Parton DensitiesOral presentationA combination is presented of all inclusive deep inelastic cross sections measured by the H1 and ZEUS collaborations in neutral and charged current unpolarised $e^{\pm}p$ scattering at HERA. The data were taken between 1994 and 2007. They span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and in Bjorken $x$. The combination method used takes the correlations of...Go to contribution page
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Voica Ana Maria Radescu (Deutsches Elektronen-Synchrotron (DE))29/04/2014, 10:05WG1: Structure Functions and Parton DensitiesOral presentationNew combined H1 and ZEUS data on neutral and charged current inclusive cross sections at HERA from all running periods 1994-2007, are used as the sole input to NLO and NNLO QCD analyses to determine new sets of parton distributions, HERAPDF2.0, with small experimental uncertainties and an estimate of model and parametrisation uncertainties. Charm and jet production data are also included in...Go to contribution page
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Prof. Robert Samuel Thorne (University College London (UK))29/04/2014, 11:00WG1: Structure Functions and Parton DensitiesOral presentationI present an update of the PDFs obtaining using the same overall framework as MSTW. In particular I concentrate on the effect of new data sets, particularly from the LHC, but compare the changes in the PDFs resulting from this source to changes due to some differences in theoretical procedure.Go to contribution page
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Carl Schmidt (Michigan State University)29/04/2014, 11:25WG1: Structure Functions and Parton DensitiesOral presentationAn update on activities of the CTEQ-TEA global analysis project will be given. This includes discussion of the latest NNLO CT10 parton distribution functions and their implications for predictions at the LHC. We also present a study of QED effects, including photon PDFs, in the CT10 analysis, and show how the ZEUS DIS plus observed photon data can constraint the initial photon PDF.Go to contribution page
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Dr Maria Ubiali (RWTH Aachen University)29/04/2014, 11:50WG1: Structure Functions and Parton DensitiesOral presentationIn this talk preliminary results on the NNPDF3.0 PDF set are presented. The novel NNPDF analysis, based on an improved fitting methodology and statistically validated by closure tests, includes the most recent data from HERA and a wide set of recent LHC data. Statistical features and tests will be presented, along with the impact of the new data on PDFs. Some of the implications for the...Go to contribution page
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Sergey Alekhin (DESY-Zeuthen)29/04/2014, 12:15WG1: Structure Functions and Parton DensitiesOral presentationWe consider impact of the recent data obtained by the LHC, Tevatron, and fixed-target experiments on the quark distributions in the nucleon with a particular focus on disentangling of different quark species. Improved determination of the poorly known strange sea distribution is obtained and the standard candle benchmarks for the Drell-Yan process at the LHC are updated.Go to contribution page
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Amanda Sarkar (University of Oxford (GB))29/04/2014, 14:20WG1: Structure Functions and Parton DensitiesOral presentationThe HERAPDF1.5 PDF set, evolved in leading order (LO) $\alpha_s$ using DGLAP evolution equations, is presented. This LO PDF is particularly useful for Monte Carlo event generators, based on LO matrix elements plus parton showers.Go to contribution page
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Hayk Pirumov (Deutsches Elektronen-Synchrotron (DE))29/04/2014, 14:45WG1: Structure Functions and Parton DensitiesOral presentationThe proton parton distribution functions (PDFs) are essential for precision physics at the LHC and other hadron colliders. Their current level of accuracy dominates the theory uncertainties in Higgs production and it affects substantially theory predictions for Beyond Standard Model high mass production. We would like to present the first stable release of the HERAFitter package - an...Go to contribution page
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Mykhailo Lisovyi (Deutsches Elektronen-Synchrotron (DE))29/04/2014, 15:10WG1: Structure Functions and Parton DensitiesOral presentationSets of parton distribution functions of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter package using the HERA data and preserving correlations between uncertainties for the LO, NLO and NNLO sets. The sets are used to study uncertainties for...Go to contribution page
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Bernd Surrow (Temple University)29/04/2014, 15:35WG1: Structure Functions and Parton DensitiesOral presentationBased upon the color-dipole picture, simple closed analytic expressions for the longitudinal and the transverse photo-absorption cross sections at low values of the Bjorken variable of $x <0.1$ have been derived. The color-dipole picture, constrained by experimental data, including the final results from the H1 and ZEUS collaborations at HERA, as well as the recent results on the...Go to contribution page
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Hannes Jung (Deutsches Elektronen-Synchrotron (DE))29/04/2014, 16:30WG1: Structure Functions and Parton DensitiesOral presentationThe combined measurements of protonโs structure functions in deeply inelastic scattering at the HERA collider provide high-precision data capable of constraining parton density functions over a wide range of the kinematic variables. We perform fits to these data using transverse momentum dependent QCD factorization and CCFM evolution. The results of the fits to precision measurements are used...Go to contribution page
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Dr Harleen Dahiya (Dr. B.R. Ambedkar National Institute of Technology)29/04/2014, 16:55WG1: Structure Functions and Parton DensitiesOral presentationWe investigate the spin flip Generalized Parton Distribution $E(x,0,t)$ in impact parameter space using the explicit light front wave functions (LFWFs) for the two-particle Fock state of the electron in QED. The Fourier transform (FT) of the GPDs by taking the longitudinal momentum transfer as zero ($\zeta=0$) gives the distribution of quarks in the transverse plane. We study the relationship...Go to contribution page
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Dr Alexey Vladimirov (Lund University)29/04/2014, 17:20WG1: Structure Functions and Parton DensitiesOral presentationWe suggest a novel way of matching the non-perturbative part of TMD with the perturbative part aimed to increase the amount of perturbative information in the TMD PDF expression. For that we perform the OPE for the TMD PDF operator in the Laguerre polynomial basis. The choice of basis is dictated by the phenomenological observation that TMDs in the region of middle-$b_T$ has Gaussian...Go to contribution page
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Alberto Accardi (Hampton U. and Jefferson Lab)29/04/2014, 17:45WG1: Structure Functions and Parton DensitiesOral presentationThe CJ (CTEQ-Jefferson Lab) collaboration has developed next-to-leading order parton distribution functions (PDFs) determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep inelastic scattering data at large x and low Q^2, nuclear corrections for deuterium targets, and a...Go to contribution page
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Paul Richard Newman (University of Birmingham (GB))30/04/2014, 08:30WG1: Structure Functions and Parton DensitiesOral presentationVarious measurements provided by the ATLAS collaboration have significant impact on parton density functions. The production of W and Z bosons inclusively or in association with charm-quark have are found to constraint the strange-quark density at medium and low Bjorken-x. Multi-Jet and photon production processes show impact on the gluon density. Off-resonance Drell Yan production at large...Go to contribution page
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Elena Yatsenko (Deutsches Elektronen-Synchrotron (DE))30/04/2014, 08:55WG1: Structure Functions and Parton DensitiesOral presentationNeutral current Drell Yan cross section is sensitive to the parton distribution functions of the proton and electroweak corrections. The measurements for two distinct kinematic regions, below the Z boson mass peak and above are performed by the ATLAS collaboration using 7 TeV pp collision data. The results are compared to NNLO QCD predictions corrected for NLO EW effects calculated using...Go to contribution page
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Heiner Wollny (CERN)30/04/2014, 09:20WG1: Structure Functions and Parton DensitiesOral presentationAt the LHC, inclusive production of W and Z bosons offer a unique window to perform stringent tests of theoretical predictions based on the Standard Model (SM) and probe its fundamental parameters. With the large samples of W and Z events collected with the CMS detector, many processes have been studied at an unprecedented precision. These measurements test the SM predictions up to...Go to contribution page
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Georg Sieber (KIT - Karlsruhe Institute of Technology (DE))30/04/2014, 09:45WG1: Structure Functions and Parton DensitiesOral presentationWe present recent CMS results related to the extraction of the strong coupling constant and constraints on parton distribution functions. Results are based in recent jet measurements performed with 2011 data taken at center-of-mass energy of 7 TeV. Alpha_S extraction is based on measurements of multijet events and inclusive jet production cross sections, with the latest to be used also for...Go to contribution page
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Georges Aad (CPPM, Aix-Marseille Universitรฉ, CNRS/IN2P3 (FR))30/04/2014, 11:00WG1: Structure Functions and Parton DensitiesOral presentationThe production of heavy flavour quarks in association with a vector boson represents an important process to study QCD. High precision is achieved in measurements of differential cross sections and comparisons are made to state-of-the-art NLO QCD calculations and different parton distribution function parameterizations. Measurement of the production of a W boson in association with a charm...Go to contribution page
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Aleko Khukhunaishvili (University of Rochester (US))30/04/2014, 11:25WG1: Structure Functions and Parton DensitiesOral presentationMeasurements of the muon charge asymmetry in inclusive pp to W+X production at sqrt(s)=7 TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 inverse femtobarns recorded with the CMS detector at the LHC. With a sample of more than twenty million W to mu nu events, the statistical precision is greatly improved in comparison to previous measurements. These new...Go to contribution page
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Ringaile Placakyte (Deutsches Elektronen-Synchrotron (DE))30/04/2014, 11:50WG1: Structure Functions and Parton DensitiesOral presentationAssociated W+charm production in proton-proton collisions at the LHC probes the strange quark in the proton at leading order. Recent CMS measurements of associated W+charm production and W muon charge asymmetry at 7 TeV are used together with HERA DIS data in a QCD analysis at next-to-leading order. The HERAFitter framework is used. The strange-quark fraction is determined as a function of the...Go to contribution page
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Vladyslav Libov (Deutsches Elektronen-Synchrotron (DE))30/04/2014, 14:00WG1: Structure Functions and Parton DensitiesOral presentationThe production of beauty and charm quarks in $ep$ interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared $5 < Q^2 < 1000$ GeV$^2$ using an integrated luminosity of 354 pb$^{-1}$. The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the...Go to contribution page
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Dr Maria Ubiali (University of Cambridge)30/04/2014, 14:25WG1: Structure Functions and Parton DensitiesOral presentationSeveral key processes at the LHC in the standard model and beyond that involve bottom quarks, such as single-top, Higgs, and weak vector boson associated production, can be described in QCD either in a 4-flavor or 5-flavor scheme. In the former, b quarks appear only in the final state and are typically considered massive. In 5-flavor schemes, calculations include b quarks in the initial state,...Go to contribution page
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Marco Guzzi (Deutsches Elektronen-Synchrotron (DE))30/04/2014, 14:50WG1: Structure Functions and Parton DensitiesOral presentationWe present phenomenological applications of DiffTop, a recently developed computer program for calculations of the differential cross section for top-quark pair production at hadron colliders. The code is based on an approximate next-to-next-to-leading order (NNLO) computation within the threshold resummation formalism in perturbative QCD. We compare the Difftop predictions with recent...Go to contribution page
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Daniel Andreas Britzger (Deutsches Elektronen-Synchrotron (DE))30/04/2014, 15:15WG1: Structure Functions and Parton DensitiesOral presentationPrecision higher order calculations in perturbative QCD for hadron-hadron collisions often require large computing power and are time consuming, in particular in next-to-next-to-leading order (NNLO) accuracy and for non-inclusive or differential quantities. However, such computations are used frequently in modern phenomenological analyses like determinations of the strong coupling constant,...Go to contribution page
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Mr Piotr Pietrulewicz (University of Vienna)30/04/2014, 15:40WG1: Structure Functions and Parton DensitiesOral presentationWe discuss a variable flavor number scheme for final state jets which can account for the effects of arbitrary finite quark masses for inclusive jet observables. The scheme is a generalization of the ACOT variable flavor number scheme with additional dynamical scales. It is based on a consistent description of massive collinear and soft modes allowing also for a treatment of rapidity...Go to contribution page
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Dr Hannu Paukkunen (University of Jyvรคskylรค)30/04/2014, 16:30WG1: Structure Functions and Parton DensitiesOral presentationWe discuss the Hessian PDF reweighting - a technique intended to estimate the effects that new measurements have on a set of PDFs. The method stems straightforwardly from considering new data in a usual $\chi^2$ fit and it naturally incorporates also non-zero values for the tolerance, $\Delta \chi^2 > 1$. In comparison to the contemporary Bayesian reweighting techniques, there is no need to...Go to contribution page
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Hannu Paukkunen (University of Jyvรคskylรค)30/04/2014, 16:55WG1: Structure Functions and Parton DensitiesOral presentationThe first p+Pb run at the LHC has opened a possibility to investigate the validity of the collinear factorization in a clearly higher energy scale than earlier in the nuclear collisions. Indeed, some processes that have been measured routinely in p+p($\overline {\rm p}$) collisions and utilized for years in free proton PDF fits, can now finally be reached also in the nuclear case. Such new...Go to contribution page
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Dr Aleksander Kusina (Southern Methodist University)30/04/2014, 17:20WG1: Structure Functions and Parton DensitiesOral presentationA global analysis of the proton PDF requires a combination of DIS, DY, and jet data. The flavor differentiation depends heavily on the DIS data, all of which is measured on nuclear targets in neutrino scattering; hence the nuclear PDFs (nPDFs) come into play. Additionally, the LHC heavy ion runs with lead beams provide information in an entirely new kinematic regime; here, the...Go to contribution page