Perturbative and nonperturbative contributions to the strange quark asymmetry in the nucleon

Abstract

There are two mechanisms for the generation of an asymmetry between the strange and anti-strange quark distributions in the nucleon: nonperturbative contributions originating from nucleons fluctuating into virtual baryon-meson pairs such as $\Lambda K$ and $\Sigma K$, and perturbative contributions arising from gluons splitting into strange and anti-strange quark pairs. While the nonperturbative contributions are dominant in the large-$x$ region, the perturbative contributions are more significant in the small-$x$ region. We calculate this asymmetry taking into account both nonperturbative and perturbative contributions, thus giving a more accurate evaluation of this asymmetry over the whole domain of $x$. We find that the perturbative contributions are generally a few times larger in magnitude than the nonperturbative contributions, which suggests that the best region to detect this asymmetry experimentally is in the region $0.02<x<0.03$. We find that the asymmetry may have more than one node, which is an effect that should be taken into account, e.g. for parameterizations of the strange and anti-strange quark distributions used in global analysis of parton distributions.

14 pages, 4 figures, figures comparing theoretical calculations with NNPDF global analysis added, accepted for publication in EPJC

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• Novel Phenomenology of Parton Distributions from the Drell-Yan Process
• Flavor Structure of the Nucleon Sea
• Nonperturbative strange-quark sea from lattice QCD, light-front holography, and meson-baryon fluctuation models
• NNLO nucleon parton distributions from a light-cone quark model dressed with its virtual meson cloud
• Parton distributions from nonlocal chiral SU(3) effective theory: Flavor asymmetries
• Nonperturbative contribution to the strange-antistrange asymmetry of the nucleon sea
• Collinear parton distributions and the structure of the nucleon sea in a light-front meson-cloud model
• Nucleon strange $s\bar{s}$ asymmetry to the $\Lambda /\bar{\Lambda }$ fragmentation
• From $D_s^{\pm }$ production asymmetry at the LHC to prompt ${\nu }_{\tau }$ at IceCube