Measurement of electrons from heavy-flavour hadron decays in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

TL;DR

This study measures electrons from heavy-flavour hadron decays in p-Pb collisions at 5.02 TeV, finding production consistent with binary scaling and supporting the interpretation of suppression in Pb-Pb collisions as hot medium effects.

Contribution

First measurement of heavy-flavour decay electrons in p-Pb collisions at 5.02 TeV, providing data on nuclear modification factors and cold nuclear matter effects.

Findings

$R_{pPb}$ is consistent with unity within uncertainties.

Heavy-flavour production scales with binary collisions.

Data agrees with models including cold nuclear matter effects.

Abstract

The production of electrons from heavy-flavour hadron decays was measured as a function of transverse momentum ($p_{\rm T}$) in minimum-bias p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV with ALICE at the LHC. The measurement covers the $p_{\rm T}$ interval $0.5<p_{\rm T}<12$ GeV/$c$ and the rapidity range $-1.06 < y_{\rm cms} < 0.14$ in the centre-of-mass reference frame. The contribution of electrons from background sources was subtracted using an invariant mass approach. The nuclear modification factor $R_{\rm pPb}$ was calculated by comparing the $p_{\rm T}$-differential invariant cross section in p-Pb collisions to a pp reference at the same centre-of-mass energy, which was obtained by interpolating measurements at $\sqrt{s}= 2.76$ TeV and $\sqrt{s} =7$ TeV. The $R_{\rm pPb}$ is consistent with unity within uncertainties of about 25%, which become larger for $p_{\rm T}$ below 1 GeV/$c$. The measurement shows that heavy-flavour production is consistent with binary scaling, so that a suppression in the high-$p_{\rm T}$ yield in Pb-Pb collisions has to be attributed to effects induced by the hot medium produced in the final state. The data in p-Pb collisions are described by recent model calculations that include cold nuclear matter effects.