Measurement of the production of high-$p_{\rm T}$ electrons from heavy-flavour hadron decays in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

TL;DR

This study measures high-$p_{\rm T}$ electrons from heavy-flavour hadron decays in Pb-Pb collisions at 2.76 TeV, revealing significant suppression due to energy loss in the quark-gluon plasma, with suppression varying by collision centrality.

Contribution

First measurement of heavy-flavour decay electrons' nuclear modification factor in Pb-Pb collisions at LHC energies, demonstrating energy loss effects for charm and beauty quarks.

Findings

Strong suppression of electrons in central collisions (up to a factor of 4).

Weaker suppression observed in semi-peripheral collisions.

Indicates energy loss of heavy quarks in the hot medium.

Abstract

Electrons from heavy-flavour hadron decays (charm and beauty) were measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass of energy $\sqrt{s_{\rm NN}}=2.76$ TeV. The transverse momentum ($p_{\rm T}$) differential production yields at mid-rapidity were used to calculate the nuclear modification factor $R_{\rm AA}$ in the interval $3<p_{\rm T}< 18$ GeV/$c$. The $R_{\rm AA}$ shows a strong suppression compared to binary scaling of pp collisions at the same energy (up to a factor of 4) in the 10% most central Pb-Pb collisions. There is a centrality trend of suppression, and a weaker suppression (down to a factor of 2) in semi-peripheral (50-80%) collisions is observed. The suppression of electrons in this broad $p_{\rm T}$ interval indicates that both charm and beauty quarks lose energy when they traverse the hot medium formed in Pb-Pb collisions at LHC.