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HK: Fachverband Physik der Hadronen und Kerne
HK 18: Hadron Structure and Spectroscopy II
HK 18.6: Talk
Tuesday, March 21, 2023, 18:30–18:45, SCH/A316
Numerical evaluation of the > nonlinear GLR-MQ equations for nuclear parton distribution functions — •Janik Rausch1, Vadim Guzey2 und Michael Klasen3 — 1Humboldt-Universität Berlin, Deutschland — 2Universität Jyväskylä, Finnland — 3Westfälische Wilhelms-Universität Münster, Deutschland
We numerically study for the first time the nonlinear GLR-MQ evolution equations for nuclear parton distribution function (nPDFs) to NLO accuracy and quantify the impact of gluon recombination at small x. Using the nCTEQ15 nPDFs as input, we confirm the importance of the nonlinear corrections for small x 10−3, whose magnitude increases with a decrease of x and an increase of the atomic number A. We find that at x=10−5 and for heavy nuclei, after the upward evolution from Q0=2 GeV to Q=10 GeV, the quark singlet Ω(x,Q2) and the gluon G(x,Q2) distributions become reduced by 9−15%, respectively. The relative effect is much stronger for the downward evolution from Q0=10 GeV to Q=2 GeV, where we find that Ω(x,Q2) is suppressed by 40%, while G(x, Q2) is enhanced by 140%. These trends propagate into the F2A(x,Q2) nuclear structure function and the FLA(x,Q2) longitudinal structure function, which after the downward evolution become reduced by 45% and enhanced by 80%, respectively. Our analysis indicates that the nonlinear effects are most pronounced in FLA(x,Q2) and are already quite sizable at x ∼ 10−3 for heavy nuclei.