Naslov
Direct photon production in Pb-Pb collisions at √sNN = 2.76 TeV

Autori
Adam, J. ; ... ; Antičić, Tome ; ... ; Erhardt, Filip ; ... ; Gotovac, Sven ; ... ; Mudnić, Eugen ; ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; ... ; Simatović, Goran ; ... ; Utrobičić, Antonija ; ... ; Vicković, Linda ; ... ; Zyzak, M.

Kolaboracija
ALICE Collaboration

Izvornik
Physics letters. B (0370-2693) 754 (2016); 235-248

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Direct photon production ; Pb-Pb ; 2.76 TeV ; ALICE ; CERN

Sažetak
Direct photon production at mid-rapidity in Pb- Pb collisions at sNN−−−√=2.76 TeV was studied in the transverse momentum range 0.9<pT<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e− pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0-20%, 20-40%, and 40-80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT≳5 GeV/c. Direct photon spectra down to pT≈1 GeV/c could be extracted for the 20-40% and 0-20% centrality classes. The significance of the direct photon signal for 0.9<pT<2.1 GeV/c is 2.6σ for the 0-20% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297±12stat±41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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