Publications

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Gluon pseudo-distributions at short distances

I. Balitsky, W. Morris, A. Radyushkin

SciPost Phys. Proc. 8, 161 (2022) · published 14 July 2022 | · pdf

We present the results that are necessary in the ongoing lattice calculations of the gluon parton distribution functions (PDFs) within the pseudo-PDF approach. We identify the two-gluon correlator functions that contain the invariant amplitude determining the gluon PDF in the light-cone $z^2 \to 0$ limit, and perform one-loop calculations in the coordinate representation in an explicitly gauge-invariant form. Ultraviolet (UV) terms, which contain $\ln (-z^2)$-dependence cancel in the reduced Ioffe-time distribution (ITD), and we obtain the matching relation between the reduced ITD and the light-cone ITD. Using a kernel form, we get a direct connection between lattice data for the reduced ITD and the normalized gluon PDF.

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DIS physics at the EIC and LHeC and connections to the future LHC and $\nu$A programs

T. J. Hobbs

SciPost Phys. Proc. 8, 155 (2022) · published 14 July 2022 | · pdf

Deeply-inelastic scattering (DIS) stands to enter a golden age with the prospect of precision programs at the Electron-Ion Collider (EIC) and Large Hadron-electron Collider (LHeC). While these programs will be of considerable importance to resolving longstanding issues in (non)perturbative QCD as well as hadronic and nuclear structure, they will also have valuable implications for a wider range of physics at the Energy and Intensity Frontiers, including at the High-Luminosity LHC (HL-LHC) and future $\nu A$ facilities. In this plenary contribution, we highlight a number of salient examples of the potential HEP impact from the complementary EIC and LHeC programs drawn from their respective Yellow Report and Whitepaper. Interested readers are encouraged to consult the extensive studies and literature from which these examples are taken for more detail.

1 citation
Time reversal-odd effects in QCD and beyond

Dylan Manna, Andrea Signori, Christine Aidala

SciPost Phys. Proc. 8, 169 (2022) · published 14 July 2022 | · pdf

In this paper we will describe a parallel between phenomenological and symmetry-based descriptions of the process dependence of the time-reversal-odd phenomena in QCD, such as the Sivers effect, with the goal of defining the essential elements that lead to such process dependence in QCD. This will then serve as a starting point to explore possible generalizations in a different gauge theory.

1 citation
Next generation proton PDFs with deuteron and nuclear uncertainties

Rosalyn L. Pearson, Richard D. Ball, Emanuele R. Nocera

SciPost Phys. Proc. 8, 026 (2022) · published 11 July 2022 | · pdf

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 (NNPDF4.0) that include theoretical uncertainties due to the use of heavy nuclear and deuteron data in the fit. We estimate these uncertainties by comparing the values of the nuclear observables computed with the nuclear PDFs against those computed with proton PDFs. For heavy nuclear PDFs we use the nuclear nNNPDF2.0 set, while for deuteron PDFs we develop an iterative procedure to determine proton and deuteron PDFs simultaneously, each including the uncertainties in the other. Accounting for nuclear uncertainties resolves some of the tensions in the global fit of the proton PDFs, especially those between the nuclear data and the extended LHC data set used in NNPDF4.0.

1 citation
Production of three isolated photons in the high-energy factorization approach

Vladimir Saleev

SciPost Phys. Proc. 8, 167 (2022) · published 14 July 2022 | · pdf

We study large-$p_T$ three-photon production at the LHC at the center-of-mass energy $\sqrt{s}=8$ TeV. We use the LO approximation of the parton Reggeization approach consistently merged with the real NLO corrections. For numerical calculations use the parton-level generator KaTie and modified KMR-type unintegrated parton distribution functions. We find good agreement between our predictions and data with the same accuracy as in the NNLO calculations based on the collinear parton model of QCD. At higher energies ($\sqrt{s}=13$ and 27 TeV) parton Reggeization approach predicts larger cross sections, up to $\sim 10$ \% and $\sim 20$ \%, respectively.

1 citation
Vision for QCD to the 2030s and Beyond

George Sterman

SciPost Phys. Proc. 8, 156 (2022) · published 14 July 2022 | · pdf

In this closing talk, I review some of the lessons we've learned about quantum chromodynamics, and reflect on what we may hope to learn in the coming years.

1 citation
CJ15 global PDF analysis with new electroweak data from the STAR and SeaQuest experiments

Sanghwa Park, Alberto Accardi, Xiaoxian Jing, Joseph F. Owens

SciPost Phys. Proc. 8, 177 (2023) · published 11 July 2023 | · pdf

We present updates to a recent CTEQ-Jefferson Lab (CJ) global analysis of parton distribution functions with a new set of electroweak data that provide unique access to quark flavor separation in the proton. In particular, recent $W$ and $Z$ boson measurements from the STAR experiment at RHIC put additional constraints on light quarks and antiquarks near the valence regime. The new measurement of the Drell-Yan lepton pair production ratio in $p+p$ and $p+d$ collisions by the SeaQuest experiment at Fermilab extends the large-$x$ coverage of the previous E866 experiment and sheds new light on the light antiquarks distribution. In this report, the impact of these new data sets on parton distribution functions will be presented with emphasis given to the flavor asymmetry of the light antiquark sea at large values of the parton momentum $x$.

1 citation
Central dileption production in proton-proton collisions with rapidity gap and with forward protons

Antoni Szczurek, Barbara Linek, Marta Luszczak

SciPost Phys. Proc. 8, 083 (2022) · published 12 July 2022 | · pdf

We discuss photon-photon fusion mechanisms of dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This is relevant for the LHC measurements by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons are taken into account and photon fluxes are expressed in terms of proton electromagnetic form factors and structure functions. Both double-elastic and single-dissociative processes are included in the analysis. Different parametrizations of the structure functions are used. Some differential distributions are presented. Some differences with respect to the results without proton measurement are discussed.

1 citation
PineAPPL: NLO EW corrections for PDF processes

Christopher Schwan

SciPost Phys. Proc. 8, 079 (2022) · published 12 July 2022 | · pdf

Modern parton distribution function (PDF) determinations either neglect higher-order corrections in the electroweak (EW) coupling or implement them approximately for a subset of PDF processes. We present a new tool, PineAPPL, which supports perturbative correction in arbitrary powers of the EW and strong coupling constant, and stores theoretical predictions independently of the used PDFs in so-called interpolation grids. These are the foundation of any PDF determination, and will allow us to perform a PDF fit taking into account EW corrections for all processes consistently. Apart from PDF determinations PineAPPL can also be used in precision phenomenology to study the impact of different choices of PDF sets, without rerunning the time-consuming computation. As an application of this tool we show Drell-Yan (DY) lepton-pair production were larger effects of NLO EW corrections can be seen that will potentially influence the PDF fit and comment about which observables are particularly suited and NLO EW PDF fit and which are not.

1 citation
Impact of LHC dijet production in pp and pPb collisions on the nNNPDF2.0 nuclear PDFs

Rabah Abdul Khalek

SciPost Phys. Proc. 8, 135 (2022) · published 14 July 2022 | · pdf

We quantify the impact of LHC dijet production measurements on the nNNPDF2.0 nuclear PDFs in twofold. First, from a proton baseline based on NNPDF3.1 and augmented by pp dijet production measurements from ATLAS and CMS at 7 and 8 TeV. Second, from a new nNNPDF2.0 global analysis including the ratio of pPb to pp dijet spectra from CMS at 5 TeV. We show that as opposed to the CMS at 5 TeV absolute pp and pPb dijet spectra, the pPb/pp ratio is well described in a nPDFs fit and provides strong constraints on the gluon of lead.

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