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We study the role of the $Z/\gamma$-interference parton distribution function (PDF) in high-energy muon colliders. We review how this PDF emerges when electroweak interactions are applied to the collinear splitting process and show that the…

High Energy Physics - Phenomenology · Physics 2025-06-18 David Marzocca , Alfredo Stanzione

We extract new parton distribution functions (PDFs) of the proton by global analysis of hard scattering data in the general-mass framework of perturbative quantum chromodynamics. Our analysis includes new theoretical developments together…

High Energy Physics - Phenomenology · Physics 2010-10-27 Hung-Liang Lai , Marco Guzzi , Joey Huston , Zhao Li , Pavel M. Nadolsky , Jon Pumplin , C. -P. Yuan

It has been argued from the earliest days of quantum chromodynamics (QCD) that at asymptotically small values of $x$ the parton distribution functions (PDFs) of the proton behave as $x^\alpha$, where the values of $\alpha$ can be deduced…

High Energy Physics - Phenomenology · Physics 2017-03-28 Richard D. Ball , Emanuele R. Nocera , Juan Rojo

Double parton distribution functions (dPDF), accessible in high energy proton-proton and proton nucleus collisions, encode information on how partons inside a proton are correlated among each other and could represent a tool to explore the…

High Energy Physics - Phenomenology · Physics 2015-09-30 Matteo Rinaldi , Sergio Scopetta , Marco Traini , Vicente Vento

A set of quasi-parton distribution functions (quasi-PDFs) have been recently proposed by Ji. Defined as the matrix elements of equal-time spatial correlations, they can be computed on the lattice and should reduce to the standard PDFs when…

High Energy Physics - Phenomenology · Physics 2015-03-03 Leonard Gamberg , Zhong-Bo Kang , Ivan Vitev , Hongxi Xing

Next-to-leading order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been perfomed, from which the gluon and the quark densities of the proton and the value of the strong coupling constant,…

High Energy Physics - Experiment · Physics 2012-08-27 ZEUS Collaboration

The interpretation of LHC data, and the assessment of possible hints of new physics, require the precise knowledge of the proton structure in terms of parton distribution functions (PDFs). We present a systematic methodology designed to…

High Energy Physics - Phenomenology · Physics 2023-12-11 Elie Hammou , Zahari Kassabov , Maeve Madigan , Michelangelo L. Mangano , Luca Mantani , James Moore , Manuel Morales Alvarado , Maria Ubiali

The neutrino deep inelastic scattering (DIS) data is very interesting for global analyses of proton and nuclear parton distribution functions (PDFs) since they provide crucial information on the strange quark distribution in the proton and…

High Energy Physics - Phenomenology · Physics 2011-11-07 K. Kovarik , I. Schienbein , F. I. Olness , J. Y. Yu , C. Keppel , J. G. Morfin , J. F. Owens , T. Stavreva

We discuss the sensitivity of theoretical predictions of observables used in searches for new physics to parton distributions (PDFs) at large momentum fraction $x$. Specifically, we consider the neutral-current Drell-Yan production of gauge…

High Energy Physics - Phenomenology · Physics 2023-01-18 Richard D. Ball , Alessandro Candido , Stefano Forte , Felix Hekhorn , Emanuele R. Nocera , Juan Rojo , Christopher Schwan

We present the first lattice results on isovector unpolarized and longitudinally polarized parton distribution functions (PDFs) at physical pion mass. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework…

High Energy Physics - Lattice · Physics 2018-09-12 Huey-Wen Lin , Jiunn-Wei Chen , Tomomi Ishikawa , Jian-Hui Zhang

The recently developed "Data Set Diagonalization" method (DSD) is applied to measure compatibility of the data sets that are used to determine parton distribution functions (PDFs). Discrepancies among the experiments are found to be…

High Energy Physics - Phenomenology · Physics 2010-04-22 Jon Pumplin

In this talk we present the results of the investigation on the so called double parton distribution functions (dPDFs), accessible quantities in high energy proton-proton and proton nucleus collisions, in double parton scattering processes…

High Energy Physics - Phenomenology · Physics 2021-02-03 Matteo Rinaldi

The kinematic region covered by the LHC experiments probes low values of Bjorken-$x$. At the scale relevant for $W$ and $Z$ production the central rapidity region covers $10^{-3} < x < 10^{-1}$. This means that it is the HERA data which…

High Energy Physics - Phenomenology · Physics 2015-03-17 Amanda Cooper-Sarkar

We present new sets of nuclear parton distribution functions (nPDFs) at next-to-leading order and next-to-next-to-leading order in perturbative QCD. Our analyses are based on deeply inelastic scattering data with charged-lepton and neutrino…

High Energy Physics - Phenomenology · Physics 2022-06-09 Ilkka Helenius , Marina Walt , Werner Vogelsang

As data become more precise, estimating theoretical uncertainties in global PDF determinations is likely to become increasingly necessary to obtain correspondingly precise PDFs. Here we present a next generation of global proton PDFs…

High Energy Physics - Phenomenology · Physics 2021-08-03 Rosalyn L. Pearson , Richard D. Ball , Emanuele R. Nocera

We summarize several projects carried out by the CTEQ global analysis of parton distribution functions (PDFs) of the proton during 2010. We discuss a recently released CT10 family of PDFs with a fixed and variable QCD coupling strength;…

High Energy Physics - Phenomenology · Physics 2011-01-04 Marco Guzzi , Pavel Nadolsky , Edmond Berger , Hung-Liang Lai , Fredrick Olness , C. -P. Yuan

The computation of the parton distribution functions (PDF) or distribution amplitudes (DA) of hadrons from first principles lattice QCD constitutes a central open problem. In this study, we present and evaluate the efficiency of a selection…

High Energy Physics - Lattice · Physics 2019-05-01 Joseph Karpie , Kostas Orginos , Alexander Rothkopf , Savvas Zafeiropoulos

A re-analysis of the NMC and SLAC data leads to a great improvement in our knowledge of the valence d and u parton distribution functions at high x. Standard parton distributions with our modifications are in good agreement with QCD…

High Energy Physics - Phenomenology · Physics 2011-02-01 U. K. Yang , A. Bodek

We present an updated global analysis of collinearly factorized nuclear parton distribution functions (PDFs) at next-to-leading order in perturbative QCD. In comparison to our previous fit, EPPS16, the present analysis includes more data…

High Energy Physics - Phenomenology · Physics 2022-05-25 Kari J. Eskola , Petja Paakkinen , Hannu Paukkunen , Carlos A. Salgado

We review various methods used to estimate uncertainties in quantum correlation functions, such as parton distribution functions (PDFs). Using a toy model of a PDF, we compare the uncertainty estimates yielded by the traditional Hessian and…

High Energy Physics - Phenomenology · Physics 2022-08-17 N. T. Hunt-Smith , A. Accardi , W. Melnitchouk , N. Sato , A. W. Thomas , M. J. White