Contribution to a conference proceedings

PUBDB-2025-02476

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Towards nucleon structure function moments and parton momentum fractions from lattice QCD

Can, K. U. (Corresponding author)Extern* ; Horsley, R. ; Rakow, P. E. L. ; Schierholz, G.Extern* ; Stüben, H. ; Young, R. D. ; Zanotti, J. M. ; QCDSF Collaboration (Collaboration Author)

2024

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Report No.: ADP-25-18/T1280; DESY-25-069; LTH 1400; PoS(QCHSC24)085; arXiv:2505.04033

Abstract: We calculate the lowest even isovector moment of the $F_2$ structure function in $2+1$-flavour lattice QCD with varying quark masses corresponding to $m_\pi \approx [410, 360, 300] \; {\rm MeV}$, at a fixed volume of $V = 48^3 \times 96$ and coupling $\beta = 5.65$ ($a = 0.068(3) \, {\rm fm}$). We directly compute the physical Compton amplitude using the Feynman-Hellmann approach and extract moments of the physical structure function. We report on the quark-mass dependence of the lowest isovector moment and estimate its value at the physical quark-mass point with $\sim 10\%$ uncertainty at fixed $Q^2$. By analysing the $Q^2$ dependence of the moments at the $SU(3)$ symmetric point ($m_\pi \approx 410 \; {\rm MeV}$), we separate the leading- and higher-twist contributions and estimate the parton momentum fraction, $\langle x \rangle_{u-d}$, which agrees with existing results.

Note: 14 pages, 4 figues. Contribution to the the XVIth Quark Confinement and the Hadron Spectrum Conference (QCHSC24) 19-24 August, 2024 Cairns Convention Centre, Cairns, Queensland, Australia preprint:626424

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Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)

Experiment(s):

1. No specific instrument

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