Nucleon strangeness polarization from varLambda /bar{varLambda } hyperon production in polarized proton\u2013proton collision at RHIC

Xiaonan Liu,Bo-Qiang Ma

doi:10.1140/epjc/s10052-019-6916-z

Xiaonan Liu, Bo-Qiang Ma

Open Access

https://doi.org/10.1140/epjc/s10052-019-6916-z

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Abstract

We calculate the inclusive production of a polarized varLambda or bar{varLambda } hyperon from the single longitudinally polarized proton and proton (pp) collision at RHIC. By comparing the data reported by the STAR Collaboration, we find that this process is sensitive to the polarization of strange and antistrange quarks of the proton in the experimental range. By introducing asymmetric coefficients with the minimization of chi ^2, we further identify the asymmetry of the polarized strange–antistrange quarks in the proton sea and find that the first moment is varDelta s approx -,0.025pm 0.019 for strange quark and varDelta bar{s} approx -,0.001pm 0.012 for antistrange quark, with central values agreeing with the light-cone meson–baryon fluctuation model prediction, the recent lattice QCD determination of strangeness polarization and results from a global QCD analysis given by the Jefferson Lab Angular Momentum (JAM) Collaboration.

Highlights

The STAR experiment at Relativistic Heavy Ion Collider (RHlC) [51,52,53] is carrying out a spin physics prog√rasm=i2n0h0iGghe-Venaenrdgy√pso=lar5iz0e0dGperVotionno–rpdreortoton collisions at gain a deeper insight into the nucleon spin structure and dynamics of the proton
By comparing recent data [55] reported by the STAR Collaboration, we find that this process is sensitive to the polarization of strange and antistrange quarks of the proton in the experimental range
By introducing asymmetric coefficients with the minimization of χ 2 in fitting data, we further identify the asymmetry of the polarized strange–antistrange quarks in the proton and find that the first moment is Δs ≈ − 0.025 ± 0.019 for strange quark and Δs ≈ − 0.001 ± 0.012 for antistrange quark, with central values agreeing with the light-cone meson–baryon fluctuation model prediction [6], the recent lattice quantum chromodynamics (QCD) determination of strangeness polarization [56] and results from a global QCD analysis given by the Jefferson Lab Angular Momentum (JAM) Collaboration [57]

Summary

Introduction

The STAR experiment at Relativistic Heavy Ion Collider (RHlC) [51,52,53] is carrying out a spin physics prog√rasm=. The experiments measuring the polarization of Λ hyperon produced in singly polarized pp collisions [54,55] may provide information about the inclusive production of hadrons and the strange and antistrange quark polarizations inside the proton. By comparing recent data [55] reported by the STAR Collaboration, we find that this process is sensitive to the polarization of strange and antistrange quarks of the proton in the experimental range. Such result agrees with the conclusions in previous studies [40,41,42]. As the Λ/Λhyperon production process in singly polarized pp collisions contains many different hard subprocesses, Sect.

The general formulae for cross section

Elucidate the kinematic regions and major subprocess

Fragmentation functions and AKK parametrization

Results

Summary