Data di Pubblicazione:
2019
Abstract:
Received 23 May 2018
Received in revised form 28 October 2018 Accepted 12 November 2018
Available online 29 December 2018 Editor: M. Doser
1. Introduction
A detailed study of the properties of the Quark–Gluon Plasma (QGP) [1] is the main goal of heavy-ion experiments at ultra- relativistic energies [2–6]. Quarkonia, i.e. bound states of charm or bottom quark–antiquark pairs, are sensitive probes of color decon- finement, due to the Quantum-Chromo Dynamics Debye screening mechanism [7–9] leading to quarkonium suppression. Moreover, the various quarkonium states have different binding energies and therefore different dissociation temperatures in a QGP, leading to sequential suppression [7,10]. Theory estimates [11] indicate that bottomonium formation may occur before QGP thermalization [12] because of the large bottom quark mass. In this situation, a quan- titative description of the influence of the medium on the bound states becomes challenging. While the dissociation temperatures vary significantly between different models [8,9], it is commonly accepted that the widths of the spectral functions of the bottomo- nium states increase compared to the widths in vacuum, due to the high temperature of the surrounding medium [13]. Finally, taking into account that feed-down processes from higher-mass resonances (around 40% for the Υ(1S) and 30% for the Υ(2S) [9]) are not negligible, the evaluation of the medium temperature via bottomonium measurements remains a complex endeavour.
The first studies of quarkonium production in heavy-ion colli- sions were devoted to charmonium states, and a suppression of their yields was observed at the SPS [14–16], at RHIC [17,18] and
⋆ E-mail address: alice-publications@cern.ch.
abstract
Inclusive Υ(1S) and Υ(2S) production have been measured in Pb–Pb collisions at the centre-of-mass
energy per nucleon–nucleon pair √sNN = 5.02 TeV, using the ALICE detector at the CERN LHC. The Υ
mesons are reconstructed in the centre-of-mass rapidity interval 2.5 < y < 4 and in the transverse-
momentum range pT < 15 GeV/c, via their decays to muon pairs. In this Letter, we present results
on the inclusive Υ(1S) nuclear modification factor RAA as a function of collision centrality, transverse
momentum and rapidity. The Υ(1S) and Υ(2S) RAA, integrated over the centrality range 0–90%, are 0.37±
0.02(stat) ± 0.03(syst) and 0.10 ± 0.04(stat) ± 0.02(syst), respectively, leading to a ratio RΥ(2S)/RΥ(1S) of AA AA
0.28±0.12(stat)±0.06(syst). The observed Υ(1S) suppression increases with the centrality of the collision and no significant variation is observed as a function of transverse momentum and rapidity.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Acharya S.; Acosta F.T.; Adamova D.; Adolfsson J.; Aggarwal M.M.; Aglieri Rinella G.; Agnello M.; Agrawal N.; Ahammed Z.; Ahn S.U.; Aiola S.; Akindinov A.; Al-Turany M.; Alam S.N.; Albuquerque D.S.D.; Aleksandrov D.; Alessandro B.; Alfaro Molina R.; Ali Y.; Alici A.; Alkin A.; Alme J.; Alt T.; Altenkamper L.; Altsybeev I.; Anaam M.N.; Andrei C.; Andreou D.; Andrews H.A.; Andronic A.; Angeletti M.; Anguelov V.; Anson C.; Anticic T.; Antinori F.; Antonioli P.; Anwar R.; Apadula N.; Aphecetche L.; Appelshauser H.; Arcelli S.; Arnaldi R.; Arnold O.W.; Arsene I.C.; Arslandok M.; Audurier B.; Augustinus A.; Averbeck R.; Azmi M.D.; Badala A.; Baek Y.W.; Bagnasco S.; Bailhache R.; Bala R.; Baldisseri A.; Ball M.; Baral R.C.; Barbano A.M.; Barbera R.; Barile F.; Barioglio L.; Barnafoldi G.G.; Barnby L.S.; Barret V.; Bartalini P.; Barth K.; Bartsch E.; Bastid N.; Basu S.; Batigne G.; Batyunya B.; Batzing P.C.; Bazo Alba J.L.; Bearden I.G.; Beck H.; Bedda C.; Behera N.K.; Belikov I.; Bellini F.; Bello Martinez H.; Bellwied R.; Beltran L.G.E.; Belyaev V.; Bencedi G.; Beole S.; Bercuci A.; Berdnikov Y.; Berenyi D.; Bertens R.A.; Berzano D.; Betev L.; Bhaduri P.P.; Bhasin A.; Bhat I.R.; Bhatt H.; Bhattacharjee B.; Bhom J.; Bianchi A.; Bianchi L.; Bianchi N.; Bielcik J.; Bielcikova J.; Bilandzic A.; Biro G.; Biswas R.; Biswas S.; Blair J.T.; Blau D.; Blume C.; Boca G.; Bock F.; Bogdanov A.; Boldizsar L.; Bombara M.; Bonomi G.; Bonora M.; Borel H.; Borissov A.; Borri M.; Botta E.; Bourjau C.; Bratrud L.; Braun-Munzinger P.; Bregant M.; Broker T.A.; Broz M.; Brucken E.J.; Bruna E.; Bruno G.E.; Budnikov D.; Buesching H.; Bufalino S.; Buhler P.; Buncic P.; Busch O.; Buthelezi Z.; Butt J.B.; Buxton J.T.; Cabala J.; Caffarri D.; Caines H.; Caliva A.; Calvo Villar E.; Camacho R.S.; Camerini P.; Capon A.A.; Carena F.; Carena W.; Carnesecchi F.; Castillo Castellanos J.; Castro A.J.; Casula E.A.R.; Ceballos Sanchez C.; Chandra S.; Chang B.; Chang W.; Chapeland S.; Chartier M.; Chattopadhyay S.; Chauvin A.; Cheshkov C.; Cheynis B.; Chibante Barroso V.; Chinellato D.D.; Cho S.; Chochula P.; Chowdhury T.; Christakoglou P.; Christensen C.H.; Christiansen P.; Chujo T.; Chung S.U.; Cicalo C.; Cifarelli L.; Cindolo F.; Cleymans J.; Colamaria F.; Colella D.; Collu A.; Colocci M.; Concas M.; Conesa Balbastre G.; Conesa del Valle Z.; Contreras J.G.; Cormier T.M.; Corrales Morales Y.; Cortese P.; Cosentino M.R.; Costa F.; Costanza S.; Crkovska J.; Crochet P.; Cuautle E.; Cunqueiro L.; Dahms T.; Dainese A.; Dani S.; Danisch M.C.; Danu A.; Das D.; Das I.; Das S.; Dash A.; Dash S.; De S.; De Caro A.; de Cataldo G.; de Conti C.; de Cuveland J.; De Falco A.; De Gruttola D.; De Marco N.; De Pasquale S.; De Souza R.D.; Degenhardt H.F.; Deisting A.; Deloff A.; Delsanto S.; Deplano C.; Dhankher P.; Di Bari D.; Di Mauro A.; Di Ruzza B.; Diaz R.A.; Dietel T.; Dillenseger P.; Ding Y.; Divia R.; Djuvsland O.; Dobrin A.; Domenicis Gimenez D.; Donigus B.; Dordic O.; Doremalen L.V.R.; Dubey A.K.; Dubla A.; Ducroux L.; Dudi S.; Duggal A.K.; Dukhishyam M.; Dupieux P.; Ehlers R.J.; Elia D.; Endress E.; Engel H.; Epple E.; Erazmus B.; Erhardt F.; Ersdal M.R.; Espagnon B.; Eulisse G.; Eum J.; Evans D.; Evdokimov S.; Fabbietti L.; Faggin M.; Faivre J.; Fantoni A.; Fasel M.; Feldkamp L.; Feliciello A.; Feofilov G.; Fernandez Tellez A.; Ferretti A.; Festanti A.; Feuillard V.J.G.; Figiel J.; Figueredo M.A.S.; Filchagin S.; Finogeev D.; Fionda F.M.; Fiorenza G.; Flor F.; Floris M.; Foertsch S.; Foka P.; Fokin S.; Fragiacomo E.; Francescon A.; Francisco A.; Frankenfeld U.; Fronze G.G.; Fuchs U.; Furget C.; Furs A.; Fusco Girard M.; Gaardhoje J.J.; Gagliardi M.; Gago A.M.; Gajdosova K.; Gallio M.; Galvan C.D.; Ganoti P.; Garabatos C.; Garcia-Solis E.; Garg K.; Gargiulo C.; Gasik P.; Gauger E.F.; Gay Ducati M.B.; Germain M.; Ghosh J.; Ghosh P.; Ghosh S.K.; Gianotti P.; Giubellino P.; Giubilato P.; Glassel P.; Gomez Coral D.M.; Gomez Ramirez A.; Gonzalez V.; Gonzalez-Zamora P.; Gorbunov S.;
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