Neutral pion and η meson production at midrapidity in Pb-Pb collisions at sNN=2.76 TeV

S Acharya,B Lim,F Guber,H Wang,T Dietel,B Ketzer,D Peresunko,D Thomas,B Chang,A Deloff,V Grabski,E Bartsch,B A Trzeciak,P Palni,I Vorobyev,S Nazarenko,S U Chung,R H Munzer,S Foertsch,S Kirsch,R Renfordt,A Velure,T S Tveter,H Zhang,T Alt,A Margotti,J Pan,L Kumar,L Betev,D Sekihata,A Tikhonov,P K Sahu,G Scioli,Y Ali,A Francisco,J Lehrbach,L Görlich,D D Chinellato,G Conesa Balbastre,O Kovalenko,P Ghosh,I R Bhat,M Keil,H Appelshäuser,D Kim,D Budnikov,Z Zhou,A Rotondi,M A Saleh,J Zhu,M Ivanov,T Kim,P I Loenne,V Zaccolo,E López Torres,I Altsybeev,M Schmidt,J Schukraft,J Zmeskal,S Sakai,S Nikulin,D M Goméz Coral,E Endress,M Niculescu,S Thakur,S Mhlanga,B Wagner,K Barth,O Busch,E A R Casula,J W Harris,G Boca,F Barile,E Yun,S Murray,P Cortese,R Bellwied,A I Sheikh,S Kim,G E Bruno,D Silvermyr,N Sharma,C Markert,Z Zhang,M Martinez Pedreira,B Hohlweger,C Jena,A Festanti,N Kondratyeva,S Yano,A Dash,B Di Ruzza,R Tieulent,A Lardeux,P Chochula,S Jaelani,J C Hamon,P Christiansen,A Tauro,N Bastid,A Chauvin,V Grigoriev,R Averbeck,P G Kuijer,M Gagliardi,M Shimomura,D Zhou,M G Poghosyan,B Paul,M Rodríguez Cahuantzi,F Antinori,S Lehner,F Erhardt,H Zhu,Y Melikyan,C Klein-Bösing,A Vauthier,M G Munhoz,M Puccio,J Mazer,C Blume,C Furget,A Toia,H Murakami,K Reygers,I Belikov,J T Buxton,A Dainese,N Zhigareva,A Morreale,S W Lindsay,A Bercuci,A Wegrzynek,L Ducroux,A Reshetin,B Rumyantsev,C Roy,A Vargas,M Petrovici,B Kileng,L Pinsky,C Hughes,R Singh,P Martinengo,R Singaraju,S Yalcin,L Vinogradov,J Pluta,F Cindolo,K Suzuki,M Fasel,V Belyaev,Ø Djuvsland,E Calvo Villar,A Sandoval,A Vasiliev,M Krzewicki,T Sinha,M Meres,L Vermunt,X Li,F Ng,J Otwinowski,L Greiner,Y Zhou,P Nomokonov,X Ren,J Park,I Stan,R Alfaro Molina,T J Humanic,S Pisano,P Ganoti,J Lien,R Schicker,S Arcelli,A Maevskaya,P Reichelt,J L Klay,V Vechernin,R Varma,S Raniwala,J Wikne,P Karczmarczyk,M B Gay Ducati,A Mischke,A Villatoro Tello,B Jacak,I G Bearden,J Castillo Castellanos,A Grelli,D B Rana,V Pozdniakov,P Huhn,I Pshenichnov,B Espagnon,A Feliciello,N Sarkar,H Caines,M Faggin,E Leogrande,A Zaman,J Vrláková,P Sahoo,A Utrobicic,A Dubla,J Rak,Y Pachmayer,S Rajput,P Roy,F Herrmann,A Khatun,Z Ahammed,A K Dubey,A Ferretti,B K Nandi,G Zinovjev,T Gunji,S R Navarro,Y Watanabe,V Singhal,R Rogalev,S Klewin,G L Usai,M M Kielbowicz,R Lietava,A Di Mauro,K Shigaki,J Klein,Z Buthelezi,C Grigoras,N Hussain,Y Pestov,C Cheshkov,C Ristea,A Kravčáková,J D Mulligan,F Prino,M Šumbera,L G E Beltran,T Sugitate,A Vodopyanov,P Sett,M C S Williams,T Virgili,C Anson,R Vernet,M Mager,S Silaeva,E Kondratyuk,D Finogeev,Z Conesa Del Valle,B Kim,N De Marco,D Horak,J Bhom,R Langoy,R Guernane,N Apadula,E Rogochaya,A Kisiel,A M Kubera,H Pei,X Lopez,V Loginov,P Crochet,A Andronic,O Villalobos Baillie,V Punin,D De Gruttola,K L Graham,V Trubnikov,Y Sibiriak,P Dupieux,C Schiaua,A Zarochentsev,J H Kang,A Ohlson,Y Zhu,G Aglieri Rinella,M S Islam,W Riegler,M Vasileiou,J Mareš,D Mühlheim,S Moretto,A M Whitehead,M Agnello,B Bhattacharjee,L Bratrud,C Loizides,S G Weber,K Münning,J Song,M Kofarago,Y Kharlov,P La Rocca,O Karavichev,S Sumowidagdo,S Porteboeuf-Houssais,X Zhang,E Stenlund,M J Kweon,P Lévai,A Morsch,G V Margagliotti,I Selyuzhenkov,V Litichevskyi,A Harton,J P Wessels,V Ivanov,M B Jadhav,B Teyssier,D Rathee,W Carena,P Hristov,X L Li,S Zou,V Lindenstruth,R Haake,M Colocci,S Siddhanta,A G Knospe,C Suire,S Das,G Tejeda Muñoz,N Poljak,P Dillenseger,V Anguelov,I.-K Yoo,W Poonsawat,A Francescon,V Samsonov,P González-Zamora,A Borissov,O Pinazza,A Masoni,S V Nesbo,A Passfeld,F Bellini,P Sarma,K Oyama,D L D Keijdener,M Nicassio,M Mukherjee,J Ghosh,D Röhrich,H Borel,D Hutter,A Dobrin,M Mohisin Khan,J J Gaardhøje,J Putschke,A Augustinus,P C Batzing,S Dudi,P Malzacher,J Cleymans,A Rakotozafindrabe,A Lattuca,E F Gauger,R C Lemmon,C Bianchin,F Carena,D Evans,P H S Y Jayarathna,C M Mitu,K Røed,M Šefčík,S Evdokimov,A Baldisseri,M Zhalov,D J Kim,A Pop,T Chujo,K Lapidus,S Chapeland,N Zardoshti,M Van Leeuwen,Y Miake,E Scomparin,S M Mahmood,L Malinina,J Stachel,S Bagnasco,S L La Pointe,J Bielčíková,D Miśkowiec,P Rosnet,Y Berdnikov,R A Negrao De Oliveira,M Vargyas,J M Gronefeld,M Malaev,M Ball,B Audurier,Q Shou,M Jercic,S Jadlovska,M R Cosentino,C Petta,X Peng,L Karayan,M Krivda,R Grosso,L Altenkamper,A Tumkin,Y Ding,E Fragiacomo,F Roukoutakis,A Sevcenco,V Vislavicius,R Nair,H A Andrews,A K Duggal,D A Moreira De Godoy,V Yurchenko,A Sarkar,I C Arsene,S Sadovsky,A Deisting,H Pereira Da Costa,A Rybicki,V Petráček,R Nayak,M Kowalski,E Willsher,B Windelband,F Meddi,A Grigoryan,F Costa,C Hills,A Shabanov,H Kim,C Garabatos,N A Martin,M K Habib,C Lagana Fernandes,S Sadhu,S Hornung,R Gupta,I Cortés Maldonado,H Hassan,S Swain,L K Graczykowski,B Schaefer,L Feldkamp,C Terrevoli,G G Barnaföldi,S Hayashi,M Wang,Z Yin,U Kebschull,E Laudi,E Meninno,U Tabassam,D F Weiser,M B Zimmermann,M Chojnacki,P Camerini,S Raha,L Leardini,R Barbera,S Fokin,U Westerhoff,H F Degenhardt,H Hushnud,J Onderwaater,E Vercellin,A Fantoni,F Soramel,P Yang,M K Köhler,A Herghelegiu,L Cunqueiro,M Arslandok,A A Capon,S Kiselev,M Masera,S Lee,E J Kim,I Ravasenga,G Eulisse,L Musa,S Delsanto,J Mitra,C Kuhn,E Bruna,H Zbroszczyk,E Scapparone,S Kundu,J Niedziela,G Luparello,B Von Haller,B T Rascanu,V Manko,V Chibante Barroso,R A Bertens,D Elia,P Bartalini,H Helstrup,R Hosokawa,F Grosa,A M Veen,S Sambyal,V Kučera,M Kim,T K Nayak,C Zampolli,R J Ehlers,F Scarlassara,G Trombetta,A Nobuhiro,V Kondratiev,J C C Noris,Y Mao,M Pikna,B Cheynis,S Panebianco,R Ilkaev,P Gasik,H Yokoyama,B Sahoo,S Dash,L Tropp,A Shangaraev,G Simonetti,P G Jones,A Fernández Téllez,C Kouzinopoulos,H Engel,H M Ljunggren,F Manso,V Manzari,R Lavicka,J Alme,D Domenicis Gimenez,G Neskovic,P Di Nezza,M Płoskoń,K Mikhaylov,V Kaplin,A Furs,M Fusco Girard,M Krüger,K Schwarz,R Arnaldi,Z Vilakazi,D Di Bari,S Bufalino,D Caffarri,A Caliva,M Suleymanov,S Choudhury,A Collu,I Sputowska,S Piano,D Thakur,A Kuryakin,J Kumar,M Mazzilli,B Mohanty,I Lakomov,T Dahms,H Natal Da Luz,F Reidt,S Vergara Limón,M R Haque,F Noferini,J Oleniacz,C Klein,M D Azmi,S Chattopadhyay,T Antičić,H R Schmidt,M Gallio,E Nappi,P Giubellino,A Bianchi,H Hamagaki,D Berzano,M M Mieskolainen,C Nattrass,O Vázquez Doce,M M Aggarwal,D Varga,J P Iddon,P Závada,A De Falco,T Peitzmann,F Rami,A A P Suaide,A Matyja,D Das,R Biswas,S Saarinen,Y Kwon,S Gotovac,Z Khabanova,C Kobdaj,I Králik,H Oeschler,A C Oliveira Da Silva,E Ryabinkin,J Eum,V Nikulin,Y Sekiguchi,S Grigoryan,M Germain,A Khuntia,F Pliquett,E Karpechev,J Crkovská,A Karasu Uysal,K Garg,T Siemiarczuk,S K Ghosh,E Hellbär,V Peskov,C Lippmann,J Viinikainen,J Kim,C Deplano,D Stocco,F Carnesecchi,L Cifarelli,M Ippolitov,J Nystrand,S De Pasquale,A Liu,K M Sielewicz,A Sharma,J Saini,V Pacik,I Szarka,T Kollegger,L Barioglio,M Lupi,J Wilkinson,M Weber,S Senyukov,R Sultanov,R Turrisi,V Papikyan,L Massacrier,F Thoresen,J G Contreras,A K Pandey,G Nooren,R Keidel,P Foka,W H Trzaska,K Gulbrandsen,R T Jimenez Bustamante,C Oppedisano,A Shabetai,V Riabov,T M Cormier,T W Snellman,A Narayan,L Fabbietti,G Batigne,G Hamar,L Ramello,B A Hess,J Faivre,A Konevskikh,M A Lisa,K Terasaki,S Shirinkin,P Gianotti,M Al-Turany,B Polichtchouk,D Pagano,M Inaba,N Tanaka,K Yamakawa,J Jadlovsky,J Bielčík,J Adolfsson,O Dordic,M Konyushikhin,S Aiola,D Sarkar,F Ronchetti,Y Corrales Morales,M Borri,A M Gago,M Oravec,W Shaikh,K Schweda,B Guerzoni,A Nyanin,B Alessandro,E Perez Lezama,M Guittiere,G Kiss,T A Broker,J F Grosse-Oetringhaus,I Das,C Jahnke,A Rehman,D Blau,P Antonioli,E Botta,F Bock,W Chang,S Lindal,N Agrawal,V Ratza,S Basu,J T Blair,F Colamaria,S Khan,K Voloshin,C Andrei,A Kalweit,T Tsuji,P Dhankher,N Bianchi,P Pillot,A Bilandzic,C De Conti,P Larionov,T Karavicheva,P Riedler,M Marchisone,A Khanzadeev,K F Hetland,M Concas,A Ortiz Velasquez,K Redlich,A Akindinov,E Cuautle,R Shahoyan,L Boldizsár,G Volpe,P Glässel,P Pareek,M A S Figueredo,K Nayak,I Kisel,W J Llope,C Hadjidakis,C Bourjau,S Gorbunov,B Batyunya,L Aphecetche,N Smirnov,E Kryshen,H Buesching,J L Bazo Alba,J Cabala,J Takahashi,G Bonomi,S Biswas,L A P Moreno,P Giubilato,M Sitta,A Alkin,V Barret,S A Voloshin,L Kreis,S Sahoo,S Cho,J Salzwedel,S Muhuri,M Lunardon,V Izucheev,L Vickovic,L O D L Pimentel,R Vértesi,M A Janik,N Zaviyalov,S Masciocchi,M A Mazzoni,H Poppenborg,G Wilk,S Costanza,D Andreou,T Richert,N K Behera,U Fuchs,J Norman,M Bregant,E Epple,A Bhasin,N Mohammadi,A Uras,D Hatzifotiadou,R C Baral,A Telesca,J De Cuveland,A Danu,A Gupta,N Jacazio,G Simatovic,C Gargiulo,G Paić,P Luettig,M Vala,A R Timmins,A Zichichi,B Dönigus,A Alici,S Kumar,R Bala,B Hippolyte,F Lehas,R Sahoo,B Erazmus,R Nania,D Voscek,C Bedda,T B Skaali,A Mastroserio,M Angeletti,E Masson,D F Lodato,B Naik,R Lea,C Lara,J Van Der Maarel,S Kar,K Senosi,S Parmar,P Kurashvili,B S Nielsen,H Hillemanns,S T Heckel,J Figiel,A Rustamov,S A Iga Buitron,S P Pathak,L Micheletti,K Ullaland,M Chartier,M Bombara,M Marquard,Y Zhang,M U Naru,S Chandra,L Bianchi,A Jusko,S Kushpil,J Mercado Pérez,R Orava,J A L Martinez,C J Myers,E Serradilla,S Filchagin,R Preghenella,D Colella,C Zhang,M Tarhini,J Margutti,D Adamová,R Divià,J S Kim,T Chowdhury,R Raniwala,F Sozzi,A Maire,K Shtejer,R Xu,J W Van Hoorne,S Trogolo,D S D Albuquerque,M L Knichel,M Floris,T Hussain,F Riggi,C Zhao,U Frankenfeld,G De Cataldo,G Herrera Corral,A Rossi,M Broz,A Mamonov,R Rui,M Bonora,P Vande Vyvre,V Muccifora,H Oh,R Bailhache,Irais Bautista Guzman ,Sidharth Kumar Prasad ,H Bello Martínez ,J Butt ,Christian Holm Christensen ,S Beolè ,G Martınez García ,Horst Sebastian Scheid ,Raimond Snellings ,K Krizkova Gajdosova ,Y F Ryabov ,Solangel Rojas Torres ,Kenneth Francis Read ,A S González ,P Bühler ,C Pruneau ,Christoph Mayer ,M Šuljić ,Sumit Kumar Saha ,K Šafařı́k ,P Kaliňák ,Matthias Richter ,M H Oliver ,A Szabó ,L.g Pereira ,A Badalá ,Emma González Hernández ,M Planinić ,A P Mohanty ,A Gómez Ramírez ,Y Schütz ,А Виноградов ,G G Fronzé ,Partha Pratim Bhaduri ,Guido Alexander Willems ,Dukhishyam Mallick ,T Vǎnát ,E Brücken ,Maksim Melnik Storetvedt ,A.b Kurepin ,Victor Jose Gaston Feuillard ,Julian Wojciech Myrcha ,P Jacobs ,K Rosłon ,H P Beck ,Panagiotis Christakoglou ,Yue Shi Lai ,Henrique José Correia Zanoli ,R Majka ,Carlos Duarte Galvan ,Marco Toppi ,A Bøgdanov ,Raúl Arteche Díaz ,M Słupecki ,Alexander Kluge ,F Křížek ,D Vranić ,A Menchaca‐Rocha ,A De ,Sandro Christian Wenzel ,L Oláh ,Sami Sakari Rasanen ,D Røhr ,Sk Noor Alam ,Rajendra Nath Patra ,Dimitar Lubomirov Mihaylov ,В Коваленко ,Miguel Ignacio Arratia Munoz ,Andreas Michael Mathis ,Lukas Nellen ,D Mal’kevich ,Przemyslaw Stefan Rokita ,E Gładysz-Dziaduś ,Mike Henry Petrus Sas ,P Braun‐Munzinger ,Meike Charlotte Danisch ,A J Lowe ,A Castro ,Г Феофилов ,M Martı́nez ,Ch Schmidt ,Ganesh Jagannath Tambave ,P Bunčić ,William Edward Witt ,I Léon Monźon ,Fernando Torales Acosta ,С Н Николаев ,Ejiro Naomi Umaka ,Martin Andreas Volkl ,Sang Un Ahn ,R Derradi De Souza ,J Seger ,Lee Stuart Barnby ,S Pochybová ,M G Târzilă ,C Ceballos Sànchez ,G Bencédi ,J Wiechuła 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doi:10.1103/physrevc.98.044901

Abstract

Neutral pion and η meson production in the transverse momentum range 1 <pT< 20 GeV/c have been measured at midrapidity by the ALICE experiment at the Large Hadron Collider (LHC) in central and semicentral Pb-Pb collisions at sNN = 2.76 TeV. These results were obtained using the photon conversion method as well as the Photon Spectrometer (PHOS) and Electromagnetic Calorimeter detectors. The results extend the upper pT reach of the previous ALICE π0 measurements from 12 to 20 GeV/c and present the first measurement of η meson production in heavy-ion collisions at the LHC. The η/π0 ratio is similar for the two centralities and reaches at high pT a plateau value of 0.457 ± 0.013stat ± 0.018syst. A suppression of similar magnitude for π0 and η meson production is observed in Pb-Pb collisions with respect to their production in pp collisions scaled by the number of binary nucleon-nucleon collisions. We discuss the results in terms of Next to Leading Order (NLO) pQCD predictions and hydrodynamic models. The measurements show a stronger suppression than observed at lower center-of-mass energies in the pT range 6 <pT< 10 GeV/c. For pT< 3 GeV/c, hadronization models describe the π0 results while for the η some tension is observed.1 MoreReceived 21 March 2018DOI:https://doi.org/10.1103/PhysRevC.98.044901Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.©2018 CERN, for the ALICE CollaborationPhysics Subject Headings (PhySH)Research AreasNuclear reactionsRelativistic heavy-ion collisionsNuclear Physics

Highlights

Quantum chromodynamics (QCD) [1], the fundamental theory of strong interactions, predicts that, above a certain critical energy density, hadrons melt into a quark-gluon plasma (QGP) [2,3]
V 0 candidates are selected with a two-dimensional elliptic selection criterion of2 +2 < 1, with αVm0ax = 0.95 and qT,max = 0.05 GeV/c, in order to increase the purity while optimizing efficiency of the photon sample
Where Nevt is the number of events in the centrality class considered, BRatio is the branching ratio [1] for the process π 0(η) → γ γ, Aε are the corresponding acceptance and efficiency corrections, and Nraw corresponds to the reconstructed π 0(η) raw yield within the rapidity range y and the transverse momentum bin pT

Summary

Introduction

Quantum chromodynamics (QCD) [1], the fundamental theory of strong interactions, predicts that, above a certain critical energy density, hadrons melt into a quark-gluon plasma (QGP) [2,3]. Such a state of matter is believed to have existed a few microseconds after the Big Bang [4]. The study and characterization of the QGP gives information on the crossover transition as well as insights on the equation of state of deconfined matter [9,10]. These transitions are expected to have occurred in the early universe and their study is of relevance to cosmology [4]

Methods

Results

Conclusion