Abstract
The production of beauty hadrons was measured via semi-leptonic decays at mid-rapidity with the ALICE detector at the LHC in the transverse momentum interval 1<p T < 8 GeV/c in minimum-bias p-Pb collisions at \( \sqrt{s_{\mathrm{NN}}}=5.02 \) TeV and in 1.3 < p T < 8 GeV/c in the 20% most central Pb-Pb collisions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV. The pp reference spectra at \( \sqrt{s_{\mathrm{NN}}}=5.02 \) TeV and \( \sqrt{s}=2.76 \) TeV, needed for the calculation of the nuclear modification factors R pPb and R PbPb, were obtained by a pQCD-driven scaling of the cross section of electrons from beauty-hadron decays measured at \( \sqrt{s}=7 \) TeV. In the p T interval 3 < p T < 8 GeV/c, a suppression of the yield of electrons from beauty-hadron decays is observed in Pb-Pb compared to pp collisions. Towards lower p T, the R PbPb values increase with large systematic uncertainties. The R pPb is consistent with unity within systematic uncertainties and is well described by theoretical calculations that include cold nuclear matter effects in p-Pb collisions. The measured R pPb and these calculations indicate that cold nuclear matter effects are small at high transverse momentum also in Pb-Pb collisions. Therefore, the observed reduction of R PbPb below unity at high p T may be ascribed to an effect of the hot and dense medium formed in Pb-Pb collisions.

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