Kinematical correlations of dielectrons from semileptonic decays of heavy mesons and Drell-Yan processes at BNL RHIC

TL;DR

This paper investigates the kinematical correlations of dielectrons from various mechanisms in proton-proton collisions at BNL RHIC, using advanced theoretical models to match experimental data and predict distributions.

Contribution

It introduces a comprehensive analysis of dielectron correlations including multiple production mechanisms using the $k_t$-factorization approach and recent decay data.

Findings

Good agreement with PHENIX dilepton mass spectrum

Predictions for transverse momentum and azimuthal angle distributions

Small contribution from diffractive charm-anticharm production

Abstract

We discuss kinematical correlations between charged leptons from semileptonic decays of open charm/bottom, leptons produced in the Drell-Yan mechanism as well as some other mechanisms not included so far in the literature in proton-proton scattering at BNL RHIC. The distributions of charm and bottom quarks/antiquarks are calculated in the framework of the $k_t$-factorization approach. For this calculation we use the Kwieci\'nski unintegrated parton distributions. The hadronization of heavy quarks is done by means of Peterson et al. fragmentation function. We use semileptonic decay functions found by fitting recent semileptonic data obtained by the CLEO and BABAR collaborations. The Drell-Yan processes were calculated including transverse momenta of quarks and antiquarks, also using the Kwieci\'nski parton distributions. We have also took into consideration reactions initiated by purely QED $\gamma^*\gamma^*$-fusion in elastic and inelastic pp collisions as well as recently proposed diffractive mechanism of exclusive charm-anticharm production. The contribution of the later mechanism is rather small. We get good description of the dilepton invariant mass spectrum measured recently by the PHENIX collaboration and present predictions for the dilepton pair transverse momentum distribution as well as distribution in azimuthal angle between electron and positron.