Anisotropic Collective Flow of Lambda Hyperons Produced in C + C Collisions at 4.2 AGeV/c

TL;DR

This study investigates the anisotropic collective flow and spectral temperatures of lambda hyperons in C+C collisions at 4.2 AGeV/c, comparing experimental results with model simulations and previous findings in heavier systems.

Contribution

It provides new measurements of lambda hyperon flow and spectral temperatures in light-ion collisions, and compares these with proton and pion emissions as well as with prior heavier system results.

Findings

Lambda flow signs match proton flow signs.

Flow parameters for lambdas agree with protons within errors.

Spectral temperatures are similar for protons and pions regardless of lambda production.

Abstract

Features of anisotropic collective flow and spectral temperatures have been determined for lambda hyperons emitted from C + C collisions, at incident momentum of 4.2 AGeV/c, measured using the Propane Bubble Chamber of JINR at Dubna. Moreover, characteristics of protons and of negative pions, emitted from those collisions, have been determined and provided for comparison. The directed and elliptic flows of lambdas both agree in sign with the corresponding flows of protons. Parameters of the directed and elliptic flows for lambdas agree further, within errors, with the corresponding parameters for the co-produced protons. This contrasts an earlier finding by the E895 Collaboration of the directed flow being significantly weaker for lambdas than protons, in the much heavier Au + Au system, at comparable incident momentum. Particle spectral temperatures in the C + C collisions have been determined focusing independently on either center-of-mass energy, transverse energy or transverse momentum distributions. For either protons or negative pions, the temperatures were found to be approximately the same, no matter whether the emission of those particles was associated with lambda production or not. Results of the measurements have been compared to the results of simulations within the Quark-Gluon String Model.