Measurement of electrons from semileptonic heavy-flavour hadron decays at midrapidity in pp and Pb–Pb collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msqrt><mml:mrow><mml:msub><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">NN</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msqrt><mml:mo linebreak="goodbreak" linebreakstyle="after">=</mml:mo><mml:mn>5.02</mml:mn></mml:math> TeV
S. Acharya, D. Adamová, S.P. Adhya, A. Adler, J. Adolfsson, Madan Mohan Aggarwal, G. Aglieri Rinella, M. Agnello, N. Agrawal, Z. Ahammed, S. Ahmad, S. U. Ahn, A. Akindinov, M. Al-Turany, Sk Noor Alam, D. S. D. Albuquerque, D. Aleksandrov, B. Alessandro, H. M. Alfanda, R. Alfaro Molina, B. Ali, Y. Ali, A. Alici, A. Alkin, J. Alme, T. Alt, L. Altenkamper, I. Altsybeev, M.N. Anaam, C. Andrei, D. Andreou, H. A. Andrews, A. Andronic, M. Angeletti, V. Anguelov, C. Anson, T. Antičić, F. Antinori, P. Antonioli, R. Anwar, N. Apadula, L. Aphecetche, H. Appelshäuser, S. Arcelli, R. Arnaldi, M. Arratia, I.C. Arsene, M. Arslandok, A. Augustinus, R. Averbeck, S. Aziz, M. D. Azmi, A. Badalà, Y.W. Baek, S. Bagnasco, Xiaozhi Bai, R. Bailhache, R. Bala, A. Baldisseri, M. Ball, S. Balouza, R. C. Baral, R. Barbera, L. Barioglio, G. G. Barnaföldi, L. S. Barnby, V. Barret, P. Bartalini, K. Barth, E. Bartsch, F. Baruffaldi, N. Bastid, S. Basu, G. Batigne, B. Batyunya, P. C. Batzing, D. Bauri, J. L. Bazo Alba, I. G. Bearden, C. Bedda, N. K. Behera, I. Belikov, F. Bellini, R. Bellwied, V. Belyaev, G. Bencedi, S. Beolè, A. Bercuci, Y. Berdnikov, D. Berényi, R.A. Bertens, D. Berzano, M.G. Besoiu, L. Betev, A. Bhasin, I.R. Bhat, M.A. Bhat, H. Bhatt, B. Bhattacharjee, A. Bianchi
Abstract
The differential invariant yield as a function of transverse momentum ( p T ) of electrons from semileptonic heavy-flavour hadron decays was measured at midrapidity in central (0–10%), semi-central (30–50%) and peripheral (60–80%) lead–lead (Pb–Pb) collisions at s NN = 5.02 TeV in the p T intervals 0.5–26 GeV/ c (0–10% and 30–50%) and 0.5–10 GeV/ c (60–80%). The production cross section in proton–proton (pp) collisions at s = 5.02 TeV was measured as well in 0.5 < p T < 10 GeV/ c and it lies close to the upper band of perturbative QCD calculation uncertainties up to p T = 5 GeV/ c and close to the mean value for larger p T . 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 AA . The measurement of the R AA in different centrality classes allows in-medium energy loss of charm and beauty quarks to be investigated. The R AA shows a suppression with respect to unity at intermediate p T , which increases while moving towards more central collisions. Moreover, the measured R 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 T in heavy-ion collisions at LHC.