Friederike Januschek
(DESY)

27/03/2012, 09:00

Structure functions

The 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...

Stefan Schmitt
(Ruprecht-Karls-Universitaet Heidelberg (DE))

27/03/2012, 09:20

Structure functions

At 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...

Uta Klein
(University of Liverpool (GB))

27/03/2012, 09:40

Structure functions

Merged 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"

Krzysztof Nowak
(Deutsches Elektronen-Synchrotron (DE))

27/03/2012, 10:10

Structure functions

A 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...

Dr
Maria Ubiali
(RWTH Aachen University)

27/03/2012, 11:00

Structure functions

A 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...

Sergey Alekhin

27/03/2012, 11:25

Structure functions

We 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...

Pedro Jimenez-Delgado
(Jefferson Lab)

27/03/2012, 11:50

Structure functions

Different 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.

290.
Uncertainties in Determining Parton Distributions at Large x: Results from the CJ Collaboration

Cynthia Keppel
(Hampton University)

27/03/2012, 12:15

Structure functions

The 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...

Johannes Bluemlein
(DESY)

27/03/2012, 12:35

Structure functions

We 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 $g_2(x,Q2)$.

Pavel Nadolsky
(Southern Methodist University)

27/03/2012, 14:00

Structure functions

I 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.

Rodolfo Sassot
(Universidad de Buenos Aires)

27/03/2012, 14:25

Structure functions

We 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...

Karol Kovarik
(University of Karlsruhe)

27/03/2012, 14:45

Structure functions

A 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...

Clara Salas
(IFT, Madrid)

27/03/2012, 15:05

Structure functions

The 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...

Hannes Jung
(Deutsches Elektronen-Synchrotron (DE))

27/03/2012, 15:25

Structure functions

We 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...

Giovanni Antonio Chirilli
(Lawrence Berkeley National Laboratory (LBNL))

27/03/2012, 16:30

Structure functions

I 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.

Prof.
Otto Nachtmann
(Institute for Theoretical Physics, University of Heidelberg)

27/03/2012, 16:45

Structure functions

The 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...

Carlo Ewerz
(ExtreMe Matter Institute EMMI, GSI, and Heidelberg University)

27/03/2012, 17:00

Structure functions

From 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...

Krzysztof Kutak
(I)

27/03/2012, 17:20

Structure functions

Motivated 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...

Franco Buccella
(Unknown)

27/03/2012, 17:35

Structure functions

First 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...

David d'Enterria
(CERN)

28/03/2012, 11:30

Structure functions

The 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...

Voica Ana Maria Radescu
(Deutsches Elektronen-Synchrotron (DE))

28/03/2012, 11:50

Structure functions

HERAFitter, 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...