More Like this

1. Parton Distribution Functions and Lattice QCD

   https://doi.org/10.1051/epjconf/201920601003  

   Lin, Huey-Wen ; Yang, A. ; Wang, W.Y. ; Ng, S.C.C. ; Chan, A.H. ; Oh, C.H. ; Phua, K.K. ( January 2019 , EPJ Web of Conferences)

   Recently, there have been rapid developments in lattice-QCD calculations of proton structure, especially in the parton distribution functions (PDFs). We overcame a longstanding obstacle and for the first time in lattice-QCD are able to directly calculate the Bjorken- x dependence of the quark, helicity and transversity distributions. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework where the full Bjorken- x dependence of finite-momentum PDFs, called “quasi-PDFs”, can be calculated on the lattice. The quasi-PDF nucleon matrix elements are renormalized non-perturbatively in RI/MOM-scheme. Following a nonperturbative renormalization of the parton quasi-distribution in a regularization-independent momentum-subtraction scheme, we establish its matching to the $ \overline {{\rm{MS}}} $ PDF and calculate the non-singlet matching coefficient at next-to-leading order in perturbation theory. In this proceeding, I will show the progress that has been made in recent years, highlighting the latest state-of-the art PDF calculations at the physical pion mass. Future impacts on the large- x global PDF fits are also discussed. 

   more » « less
2. NNLO constraints on proton PDFs from the SeaQuest and STAR experiments and other developments in the CTEQ-TEA global analysis

   https://doi.org/10.21468/SciPostPhysProc.8.005  

   Guzzi, Marco ; Hobbs, Timothy ; Hou, Tie-Jiun ; Jing, Xiaoxian ; Xie, Keping ; Courtoy, Aurore ; Dulat, Sayipjamal ; Gao, Jun ; Huston, Joey ; Nadolsky, Pavel ; et al ( January 2022 , SciPost Physics Proceedings)

   We review progress in the global QCD analysis by the CTEQ-TEA group since the publication of CT18 parton distribution functions (PDFs) in the proton. Specifically, we discuss comparisons of CT18 NNLO predictions with the LHC 13 TeV measurements as well as with the FNAL SeaQuest and BNL STAR data on lepton pair production. The specialized CT18X PDFs approximating saturation effects are compared with the CT18sx PDFs obtained using NLL/NLO small-$x$ resummation. Short summaries are presented for the special CT18 parton distributions with fitted charm and with lattice QCD inputs. A recent comparative analysis of the impact of deuteron nuclear effects on the parton distributions by the CTEQ-JLab and CTEQ-TEA groups is summarized. 

   more » « less
3. The PDFLattice2017 workshop: a summary report

   https://doi.org/10.22323/1.297.0211  

   Nocera, Emanuele Roberto ; Lin, Huey-Wen ; Olness, Fred ; Orginos, Kostas ; Rojo, Juan ( December 2017 , XXV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2017))

   The workshop on Parton Distributions and Lattice Calculations in the LHC era (PDFLattice2017) was hosted at Balliol College, Oxford (UK), from 22nd to 24th March 2017. The workshop brought together the lattice-QCD and the global-fit physicists who devote their efforts to determine the parton distribution functions (PDFs) of the proton. The goals were to make the two communities more familiar between each other, review developments from both sides, and set precision targets for lattice calculations so that they can contribute, together with the forthcoming experimental input, to the next generation of PDF determinations. This contribution summarises the relevant outcome of the workshop, in anticipation of a thorough white paper. 

   more » « less
4. Heavy-flavor impact on CTEQ-TEA global QCD analyses

   https://doi.org/10.1051/epjconf/202227000004  

   Guzzi, Marco ; Ablat, Alim ; Dulat, Sayipjamal ; Hou, Tie-Jiun ; Nadolsky, Pavel ; Sitiwaldi, Ibrahim ; Xie, Keping ; Yuan, C.-P. ( January 2022 , EPJ Web of Conferences)

   Bruno, G.E. ; Chiodini, G. ; Colangelo, P. ; Corianò, C. ; Creanza, D.M. ; De Fazio, F. ; Nappi, E. (Ed.)

   We discuss heavy-flavor production at hadron colliders in recent global QCD analyses to determine parton distribution functions (PDFs) in the proton. We discuss heavy-flavor treatments in precision theory predictions at the LHC. In particular, we discuss factorization schemes in presence of heavy flavors in proton-proton collisions, as well as the impact of heavy-flavor production at the LHC on PDFs. We show results of recent updates beyond CT18, the latest global QCD analysis from the CTEQ-TEA group. 

   more » « less
5. Pion PDFs confronted by fixed-target charmonium production

   https://doi.org/10.1007/s43673-023-00085-4  

   Chang, Wen-Chen ; Hsieh, Chia-Yu ; Lian, Yu-Shiang ; Peng, Jen-Chieh ; Platchkov, Stephane ; Sawada, Takahiro ( July 2023 , AAPPS Bulletin)

   The pion, as the Goldstone boson of the strong interaction, is the lightest QCD bound state and responsible for the long-range nucleon-nucleon interaction inside the nucleus. Our knowledge on the pion partonic structure is limited by the existing Drell-Yan data which are primarily sensitive to the pion valence-quark distributions. The recent progress of global analysis of pion’s parton distribution functions (PDFs) utilizing various experimental approaches are introduced. From comparisons between the pion-induced$$J/\psi$$$J/\psi$and$$\psi (2S)$$$\psi \left(2S\right)$production data with theoretical calculations using the CEM and NRQCD models, we show how these charmonium production data could provide useful constraints on the pion PDFs.

    

   more » « less