Heavy lepton pair production in nucleus-nucleus collisions at LHC energy - a case study

TL;DR

This study analyzes tau lepton pair production in lead-lead collisions at LHC energies, highlighting the dominance of Drell-Yan processes and the potential to detect quark-gluon plasma signals through tau pair yields.

Contribution

It provides the first detailed analysis of tau lepton pair production in heavy-ion collisions at LHC energies, considering various production mechanisms and their relative contributions.

Findings

Drell-Yan process dominates tau pair production from 4 to 20 GeV.

Tau pair yield ratio exceeds unity for 4-6 GeV, indicating QGP detection potential.

Thermal sources contribute less compared to Drell-Yan in the studied mass range.

Abstract

We present a study of $\tau^{+}\tau^{-}$ lepton pair production in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.5 TeV. The larger $\tau^{\pm}$ mass ($\sim$ 1.77 GeV) compared to $e^{\pm}$ and $\mu^{\pm}$ leads to considerably small hadronic contribution to the $\tau^{+}\tau^{-}$ pair invariant mass ($M$) distribution relative to the production from thermal partonic sources. The quark-anti-quark annihilation processes via intermediary virtual photon, Z and Higgs bosons have been considered for the production of $ \tau^{+}\tau^{-}$. We observe that the contribution from Drell-Yan process dominates over thermal yield for $\tau^{+}\tau^{-}$ pair mass from 4 to 20 GeV at the LHC energy. We also present the ratio of $\tau$ lepton pair yields for nucleus-nucleus collisions relative to yields from p+p collisions scaled by number of binary collisions at LHC energies as a function $\tau$ pair mass. The ratio is found to be significantly above unity for the mass range 4 to 6 GeV. This indicates the possibility of detecting $\tau^{+}\tau^{-}$ pair from quark gluon plasma (QGP) in the mass window $4\leq M$(GeV)$\leq 6$.