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Momentum and spatial distributions of quarks and gluons inside hadrons are typically encoded in the so-called generalized parton distributions (GPDs). GPDs are multi-dimensional quantities that are very challenging to extract, both…

A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work significantly extends previous CTEQ and other global analyses on two fronts: (i) a full treatment…

High Energy Physics - Phenomenology · Physics 2011-07-18 J. Pumplin , D. R. Stump , J. Huston , H. L. Lai , P. Nadolsky , W. K. Tung

We present a detailed comparison of the most recent sets of NNLO PDFs from the ABM, CT, HERAPDF, MSTW and NNPDF collaborations. We compare parton distributions at low and high scales and parton luminosities relevant for LHC phenomenology.…

We present a numerical lattice quantum chromodynamics calculation of isovector form factors and the first few moments of the isovector structure functions of the nucleon. The calculation employs two degenerate dynamical flavors of…

High Energy Physics - Lattice · Physics 2008-12-18 Huey-Wen Lin , Tom Blum , Shigemi Ohta , Shoichi Sasaki , Takeshi Yamazaki

Parton distributions encode the momentum-space structure and, in their generalizations, the spatial tomography of quarks and gluons inside hadrons, the building blocks of visible matter. We present a unified neural-network approach that…

High Energy Physics - Lattice · Physics 2026-05-29 Min-Huan Chu , Krzysztof Cichy , Martha Constantinou , Paweł Sznajder , Jakub Wagner

We discuss the two most recent global analyses of nuclear parton distribution functions within the nCTEQ approach. LHC data on $W/Z$-boson, single-inclusive hadron and heavy quark/quarkonium production are shown to not only significantly…

High Energy Physics - Phenomenology · Physics 2022-10-20 M. Klasen , P. Duwentäster , T. Jezo , K. Kovarik , A. Kusina , J. G. Morfin , K. F. Muzakka , F. I. Olness , R. Ruiz , I. Schienbein , J. Y. Yu

We present, for the first time, an \textit{ab initio} calculation of the individual up, down and strange quark helicity parton distribution functions for the proton. The calculation is performed within the twisted mass clover-improved…

High Energy Physics - Lattice · Physics 2021-03-17 C. Alexandrou , M. Constantinou , K. Hadjiyiannakou , K. Jansen , F. Manigrasso

We present a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon. It can be applied in the framework of convolution formalism to the deep-inelastic structure functions…

High Energy Physics - Phenomenology · Physics 2014-11-17 H. Holtmann , A. Szczurek , J. Speth

Nuclear parton distribution functions (NPDFs) are determined by global analyses of experimental data on structure-function ratios F_2^A/F_2^{A'} and Drell-Yan cross-section ratios \sigma_{DY}^A/\sigma_{DY}^{A'}. The analyses are done in the…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Hirai , S. Kumano , T. -H. Nagai

Lattice QCD offers the possibility of computing parton distributions from first principles, although not in the usual $\overline{MS}$ factorization scheme. We study in this paper the evolution of non-singlet parton distribution functions…

High Energy Physics - Lattice · Physics 2023-11-01 H. Dutrieux , J. Karpie , C. Monahan , K. Orginos , S. Zafeiropoulos

We present results on the quark unpolarized, helicity and transversity parton distributions functions of the nucleon. We use the quasi-parton distribution approach within the lattice QCD framework and perform the computation using an…

High Energy Physics - Lattice · Physics 2021-09-22 Constantia Alexandrou , Martha Constantinou , Kyriakos Hadjiyiannakou , Karl Jansen , Floriano Manigrasso

We present a high-statistics lattice QCD determination of the valence parton distribution function (PDF) of the pion, with a mass of 300 MeV, using two very fine lattice spacings of $a=0.06$ fm and 0.04 fm. We reconstruct the $x$-dependent…

We present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data…

High Energy Physics - Phenomenology · Physics 2016-03-09 Sayipjamal Dulat , Tie Jiun Hou , Jun Gao , Marco Guzzi , Joey Huston , Pavel Nadolsky , Jon Pumplin , Carl Schmidt , Daniel Stump , C. P. Yuan

We present a systematic study of neutron-proton scattering in Nuclear Lattice Effective Field Theory (NLEFT), in terms of the computationally efficient radial Hamiltonian method. Our leading-order (LO) interaction consists of smeared, local…

We develop a non-perturbative model for valence parton distribution functions (PDFs) based on the mean field interactions of valence quarks in the nucleonic interior. The main motivation for the model is to obtain a mean field description…

High Energy Physics - Phenomenology · Physics 2021-12-08 Christopher Leon , Misak Sargsian

We present a model-independent determination of the nuclear parton distribution functions (nPDFs) using machine learning methods and Monte Carlo techniques based on the NNPDF framework. The neutral-current deep-inelastic nuclear structure…

High Energy Physics - Phenomenology · Physics 2020-10-28 Rabah Abdul Khalek , Jacob J. Ethier , Juan Rojo , Gijs van Weelden

This work studies collinearly factorizable nuclear parton distribution functions (nPDFs) in perturbative Quantum Chromodynamics (QCD) at next-to-leading order in the light of hadron-nucleus collision data which have not been included in…

High Energy Physics - Phenomenology · Physics 2019-12-18 Petja Paakkinen

We present preliminary results for fits of parton distribution functions (PDFs) which include the resummation of small-$x$ logarithms at NLLx accuracy, performed in the NNPDF framework. We observe an improvement in the description of DIS…

High Energy Physics - Phenomenology · Physics 2017-07-07 Luca Rottoli , Marco Bonvini

In this article we obtain a new set of nuclear parton distribution functions (nuclear PDFs) at next-to-leading order and next-to-next-to-leading order accuracy in perturbative QCD. The common nuclear deep-inelastic scattering (DIS) data…

High Energy Physics - Phenomenology · Physics 2021-08-17 Hamzeh Khanpour , Maryam Soleymaninia , S. Atashbar Tehrani , Hubert Spiesberger , Vadim Guzey

We investigate the connection of lattice calculations of moments of isovector parton distributions to the physical regime through extrapolations in the quark mass. We consider the one pion loop renormalisation of the nucleon matrix elements…

High Energy Physics - Lattice · Physics 2009-11-07 W. Detmold , W. Melnitchouk , A. W. Thomas