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

The differential invariant cross section as a function of transverse momentum ($p_\rm{T}$) of electrons from semileptonic heavy-flavour hadron decays was measured at midrapidity in proton-proton (pp) collisions at $\sqrt{s}$ = 5.02 TeV in the $p_\rm{T}$ interval 0.5-10 GeV/$c$, as well as the invariant yield in central (0-10%), semi-central (30-50%) and peripheral (60-80%) lead-lead (Pb-Pb) collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV in the $p_{\rm{T}}$ intervals 0.5-26 GeV/$c$ (0-10% and 30-50%) and 0.5-10 GeV/$c$ (60-80%). The modification of the electron yield with respect to what is expected for an incoherent superposition of nucleon-nucleon collisions is evaluated by measuring the nuclear modification factor $R_{\rm{AA}}$. The measurement of the $R_{\rm{AA}}$ in different centrality classes allows in-medium energy loss of charm and beauty quarks to be investigated. Moreover, the measured $R_{\rm{AA}}$ is sensitive to the modification of the parton distribution functions (PDF) in nuclei, like nuclear shadowing, which causes a suppression of the heavy-quark production at low $p_\rm{T}$ in heavy-ion collisions at LHC.

 

Submitted to: PLB
e-Print: arXiv:1910.09110 | PDF | inSPIRE
CERN-EP-2019-205

Figures

Figure 1

$p_\mathrm{T}$-differential invariant production cross section of electrons from semileptonic heavy-flavour hadron decays in pp collisions at $\sqrt{s}=5.02$~TeV. The measurement is compared with the FONLL calculation . In the bottom panel, the ratios with respect to the central values of the FONLL calculation are shown. An additional 2.1\% normalisation uncertainty, due to the measurement of the minimum bias triggered cross section , is not shown in the results.
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Figure 2

$p_\mathrm{T}$-differential invariant yield in central (0--10\%), semi-central (30--50\%), and peripheral (60--80\%) Pb--Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV.
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Figure 3

Nuclear modification factor of electrons from semileptonic heavy-flavour hadron decays measured in the three centrality intervals in Pb--Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV.
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Figure 4

Nuclear modification factor of electrons semileptonic from heavy-flavour hadron decays measured in 0--10\% and 30--50\% centrality in Pb--Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV compared with model predictions .
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[png]   [pdf]   [eps]