Direct photon production at low transverse momentum in proton-proton collisions at root s=2.76 and 8 TeV

Acharya, S.; Acosta, F. T.; Adamová, Dagmar; Bielčík, J.; Bielčíková, Jana; Broz, M.; Contreras, J. G.; Horák, D.; Křížek, Filip; Kučera, Vít; Kushpil, Svetlana; Lavička, R.; Mareš, Jiří A.; Petráček, V.; Šumbera, Michal; Závada, Petr

doi:https://dx.doi.org/10.1103/PhysRevC.99.024912

Number of the records: 1

Direct photon production at low transverse momentum in proton-proton collisions at root s=2.76 and 8 TeV

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SYSNO ASEP	0503174
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Direct photon production at low transverse momentum in proton-proton collisions at root s=2.76 and 8 TeV
Author(s)	Acharya, S. (IN) Acosta, F. T. (US) Adamová, Dagmar (UJF-V)_{RID, ORCID, SAI} Bielčík, J. (CZ) Bielčíková, Jana (UJF-V)_{RID, ORCID, SAI} Broz, M. (CZ) Contreras, J. G. (CZ) Horák, D. (CZ) Křížek, Filip (UJF-V)_{RID, ORCID, SAI} Kučera, Vít (UJF-V)_RID Kushpil, Svetlana (UJF-V)_{RID, ORCID, SAI} Lavička, R. (CZ) Mareš, Jiří A. (FZU-D)_{RID, ORCID} Petráček, V. (CZ) Šumbera, Michal (UJF-V)_{RID, ORCID, SAI} Závada, Petr (FZU-D)_{RID, ORCID}
Number of authors	1003
Article number	024912
Source Title	Physical Review C. - : American Physical Society - ISSN 2469-9985 Roč. 99, č. 2 (2019)
Number of pages	19 s.
Publication form	Print - P
Language	eng - English
Country	US - United States
Keywords	ALICE collaboration ; heavy ion collisions ; LHC
Subject RIV	BG - Nuclear, Atomic and Molecular Physics, Colliders
OECD category	Nuclear physics
Subject RIV - cooperation	Institute of Physics - Elementary Particles and High Energy Physics
R&D Projects	LTT17018 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
Research Infrastructure	CERN-CZ - 90058 - Fyzikální ústav AV ČR, v. v. i.
Method of publishing	Open access
Institutional support	FZU-D - RVO:68378271 ; UJF-V - RVO:61389005
UT WOS	000459308900004
EID SCOPUS	85062465759
DOI	10.1103/PhysRevC.99.024912
Annotation	Measurements of inclusive and direct photon production at midrapidity in pp collisions at root s = 2.76 and 8 TeV are presented by the ALICE experiment at the LHC. The results are reported in transverse momentum ranges of 0.4 < p(T) < 10 GeV/c and 0.3 < p(T) < 16 GeV/c, respectively. Photons are detected with the electromagnetic calorimeter (EMCal) and via reconstruction of e(+) e(-) pairs from conversions in the ALICE detector material using the central tracking system. For the final measurement of the inclusive photon spectra the results are combined in the overlapping p(T), interval of both methods. Direct photon spectra, or their upper limits at 90% C.L. are extracted using the direct photon excess ratio R-gamma, which quantifies the ratio of inclusive photons over decay photons generated with a decay-photon simulation. An additional hybrid method, combining photons reconstructed from conversions with those identified in the EMCal, is used for the combination of the direct photon excess ratio R-gamma, as well as the extraction of direct photon spectra or their upper limits. While no significant signal of direct photons is seen over the full p(T), range, R-gamma, for p(T), > 7 GeV/c is at least one sigma above unity and consistent with expectations from next-to-leading order pQCD calculations.
Workplace	Nuclear Physics Institute
Contact	Markéta Sommerová, sommerova@ujf.cas.cz, Tel.: 266 173 228
Year of Publishing	2020
Electronic address	https://doi.org/10.1103/PhysRevC.99.024912

Number of the records: 1