Eur. Phys. J. C (2012) 72: 2250
https://doi.org/10.1140/epjc/s10052-012-2250-4

Regular Article - Theoretical Physics

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

¹ Institute of High Energy Physics, CAS, P.O. Box 918(4), Beijing, 100049, China
² Theoretical Physics Center for Science Facilities, CAS, Beijing, 100049, China
³ Institute of Fundamental Science, Massey University, Private Bag 11 222, Palmerston North, New Zealand
⁴ College of Nuclear Science and Technology, Beijing Normal University, Beijing, 100875, China

^* e-mail: fenggq@ihep.ac.cn

Received: 13 September 2012
Revised: 19 November 2012
Published online: 1 December 2012

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 ΛK and ΣK, 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.