DOE OSTI · 3011943
Dielectron production in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02TeV
Abstract
The first measurement of the 𝑒 + 𝑒 − pair production at midrapidity and low invariant mass in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV at the Large Hadron Collider is presented. The yield of 𝑒 + 𝑒 − pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass (𝑚𝑒𝑒) and pair transverse momentum (𝑝 T,𝑒𝑒 ) ranges 𝑚 𝑒𝑒 < 3.5 GeV/𝑐 2 and 𝑝 T,𝑒𝑒 < 8 GeV/𝑐. For 0.18 < 𝑚 𝑒𝑒 < 0.5 GeV/𝑐 2 the ratio of data to the cocktail of hadronic contributions amounts to 1.40 ± 0.11(stat.) ± 0.23 (syst.) ± 0.16 (cocktail) and 1.42 ± 0.11 (stat.) ± 0.23 (syst.)$^{+0.24}_{−0.29}$ (cocktail), including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal 𝑒+𝑒− pairs from the hadronic and partonic phases. In the intermediate-mass range (1.2 < 𝑚 𝑒𝑒 < 2.6 GeV/𝑐 2 ), the pair transverse impact parameter of the 𝑒 + 𝑒 − pairs (DCA𝑒𝑒, where “DCA” denotes “distance of closest approach”) is used for the first time in Pb-Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of 𝑒 + 𝑒 − pairs from $𝑐\bar{𝑐}$ and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV is reported via the study of virtual direct photons in the transverse momentum range 1 < 𝑝 T < 5 GeV/𝑐. A model including prompt photons, as well as photons from the preequilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties.
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Acharya, S. [Université Clermont Auvergne, CNRS/IN2P3, LPC] (ORCID:0000000292135329), Adamová, D. [Nuclear Physics Institute of the Czech Academy of Sciences] (ORCID:0000000205047428), Aglieri Rinella, G. [European Organization for Nuclear Research (CERN)] (ORCID:0000000296113696), Agnello, M. [Dipartimento DISAT del Politecnico and Sezione INFN] (ORCID:0000000207605075), Agrawal, N. [INFN, Sezione di Bologna] (ORCID:0000000303489836), Ahammed, Z. [Variable Energy Cyclotron Centre, Homi Bhabha National Institute] (ORCID:0000000152417412), Ahmad, S. [Department of Physics, Aligarh Muslim University] (ORCID:0000000304975705), Ahn, S. U. [Korea Institute of Science and Technology Information] (ORCID:000000018847489X), Ahuja, I. [Faculty of Science, P.J. Šafárik University] (ORCID:0000000244171392), Akindinov, A. [Affiliated with an institute covered by a cooperation agreement with CERN] (ORCID:0000000273883022), Al-Turany, M. [Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH] (ORCID:0000000280714497), Aleksandrov, D. [Affiliated with an institute covered by a cooperation agreement with CERN] (ORCID:0000000297197035), Alessandro, B. [INFN, Sezione di Torino] (ORCID:0000000196804940), Alfanda, H. M. [Central China Normal University] (ORCID:0000000256592119), Alfaro Molina, R. [Instituto de Física, Universidad Nacional Autónoma de México] (ORCID:0000000247137069), Ali, B. [Department of Physics, Aligarh Muslim University] (ORCID:0000000208777979), Alici, A. [Dipartimento di Fisica e Astronomia dell'Università] (ORCID:0000000336184617), Alizadehvandchali, N. [University of Houston] (ORCID:0009000073651064), Alkin, A. [European Organization for Nuclear Research (CERN)] (ORCID:0000000222055761), Alme, J. [Department of Physics and Technology, University of Bergen] (ORCID:0000000301770536), Alocco, G. [INFN, Sezione di Cagliari] (ORCID:0000000189109173), Alt, T. [Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt] (ORCID:0009000548625370), Altamura, A. R. [INFN, Sezione di Bari] (ORCID:0000000180485500), Altsybeev, I. [Technische Universität München] (ORCID:0000000280797026), Alvarado, J. R. [High Energy Physics Group, Universidad Autónoma de Puebla] (ORCID:0000000250381337), Anaam, M. N. [Central China Normal University] (ORCID:0000000261804243), Andrei, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering] (ORCID:0000000185350680), Andreou, N. [University of Derby] (ORCID:0009000974576866), Andronic, A. [Universität Münster, Institut für Kernphysik] (ORCID:0000000223726117), Anguelov, V. [Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg] (ORCID:0009000602362680), Antinori, F. [INFN, Sezione di Padova] (ORCID:0000000273668891), Antonioli, P. [INFN, Sezione di Bologna] (ORCID:0000000175163726), Apadula, N. [Lawrence Berkeley National Laboratory] (ORCID:0000000254786120), Aphecetche, L. [SUBATECH, IMT Atlantique, Nantes Université, CNRS-IN2P3] (ORCID:0000000176623878), Appelshäuser, H. [Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt] (ORCID:0000000306147671), Arata, C. [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3] (ORCID:0009000219907289), Arcelli, S. [Dipartimento di Fisica e Astronomia dell'Università] (ORCID:0000000163679215), Aresti, M. [Dipartimento di Fisica dell'Università] (ORCID:0000000331426787), Arnaldi, R. [INFN, Sezione di Torino] (ORCID:0000000166989577), Arneiro, J. G. M. C. A. [Universidade de São Paulo (USP)] (ORCID:0000000251942079), Arsene, I. C. [Department of Physics, University of Oslo] (ORCID:0000000323169565), Arslandok, M. [Yale University] (ORCID:0000000238888303), Augustinus, A. [European Organization for Nuclear Research (CERN)] (ORCID:0009000854606805), Averbeck, R. [Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH] (ORCID:0000000342774963), Azmi, M. D. [Department of Physics, Aligarh Muslim University] (ORCID:0000000225016856), Baba, H. [University of Tokyo], Badalà, A. [INFN, Sezione di Catania] (ORCID:0000000205694828), Bae, J. [Sungkyunkwan University] (ORCID:0009000848068019), Baek, Y. W. [Gangneung-Wonju National University] (ORCID:0000000243434883), Bai, X. [University of Science and Technology of China] (ORCID:000900099085079X), Bailhache, R. [Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt] (ORCID:0000000179874592), Bailung, Y. [Indian Institute of Technology Indore] (ORCID:0000000311720225), Balbino, A. [Dipartimento DISAT del Politecnico and Sezione INFN] (ORCID:0000000203591403), Baldisseri, A. [Université Paris-Saclay, Centre d'Etudes de Saclay (CEA), IRFU, Départment de Physique Nucléaire (DPhN)] (ORCID:000000026186289X), Balis, B. [AGH University of Krakow] (ORCID:0000000230824209), Banerjee, D. [Bose Institute, Department of Physics] (ORCID:0000000157437578), Banoo, Z. [Physics Department, University of Jammu] (ORCID:0000000271783001), Barbera, R. [Dipartimento di Fisica e Astronomia dell'Università] (ORCID:0000000159716415), Barile, F. [Dipartimento Interateneo di Fisica ‘M. Merlin'] (ORCID:0000000320881290), Barioglio, L. [Technische Universität München] (ORCID:0000000273289154), Barlou, M. [National and Kapodistrian University of Athens, School of Science, Department of Physics], Barman, B. [Gauhati University, Department of Physics], Barnaföldi, G. G. [HUN-REN Wigner Research Centre for Physics] (ORCID:0000000192236480), Barnby, L. S. [Nuclear Physics Group, STFC Daresbury Laboratory] (ORCID:0000000173579904), Barret, V. [Université Clermont Auvergne, CNRS/IN2P3, LPC] (ORCID:0000000306119283), Barreto, L. [Universidade de São Paulo (USP)] (ORCID:0000000264540052), Bartels, C. [University of Liverpool] (ORCID:0009000233714483), Barth, K. [European Organization for Nuclear Research (CERN)] (ORCID:0000000176331189), Bartsch, E. [Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt] (ORCID:0009000679284203), Bastid, N. [Université Clermont Auvergne, CNRS/IN2P3, LPC] (ORCID:0000000269058345), Basu, S. [Lund University Department of Physics, Division of Particle Physics] (ORCID:0000000306878124), Batigne, G. [SUBATECH, IMT Atlantique, Nantes Université, CNRS-IN2P3] (ORCID:0000000186386300), Battistini, D. [Technische Universität München] (ORCID:0009000001993372), Batyunya, B. [Affiliated with an international laboratory covered by a cooperation agreement with CERN] (ORCID:0009000929746985), Bauri, D. [Indian Institute of Technology Bombay (IIT)], Bazo Alba, J. L. [Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú] (ORCID:0000000191489101), Bearden, I. G. [Niels Bohr Institute, University of Copenhagen] (ORCID:0000000327843094), Beattie, C. [Yale University] (ORCID:0000000174314051), Becht, P. [Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH] (ORCID:0000000279083288), Behera, D. [Indian Institute of Technology Indore] (ORCID:0000000225997957), Belikov, I. [Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France] (ORCID:0009000559228936), Bell Hechavarria, A. D. C. [Universität Münster, Institut für Kernphysik] (ORCID:0000000204426549), Bellini, F. [Dipartimento di Fisica e Astronomia dell'Università] (ORCID:0000000334984661), Bellwied, R. [University of Houston] (ORCID:0000000231560188), Belokurova, S. [Affiliated with an institute covered by a cooperation agreement with CERN] (ORCID:0000000248623384), Beltran, Y. A. V. [High Energy Physics Group, Universidad Autónoma de Puebla] (ORCID:0009000282124789), Bencedi, G. [HUN-REN Wigner Research Centre for Physics] (ORCID:0000000290405292), Beole, S. [Dipartimento di Fisica dell'Università] (ORCID:0000000346738038), Berdnikov, Y. [Affiliated with an institute covered by a cooperation agreement with CERN] (ORCID:0000000303095917), Berdnikova, A. [Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg] (ORCID:0000000337057898), Bergmann, L. [Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg] (ORCID:0009000455112496), Besoiu, M. G. [Institute of Space Science (ISS)] (ORCID:0000000152532517), Betev, L. [European Organization for Nuclear Research (CERN)] (ORCID:0000000213731844), Bhaduri, P. P. [Variable Energy Cyclotron Centre, Homi Bhabha National Institute] (ORCID:0000000178833190), Bhasin, A. [Physics Department, University of Jammu] (ORCID:0000000236878179), Bhat, M. A. [Bose Institute, Department of Physics] (ORCID:0000000236431502), Bhattacharjee, B. [Gauhati University, Department of Physics] (ORCID:0000000237550992), Bianchi, L. [Dipartimento di Fisica dell'Università] (ORCID:0000000316648189), Bianchi, N. [INFN, Laboratori Nazionali di Frascati] (ORCID:0000000168612810), Bielčík, J. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague] (ORCID:0000000349402441). 2025-11-18. Dielectron production in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02TeV. https://doi.org/10.1103/xl6m-vbqk
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