Event-shape and multiplicity dependence of freeze-out radii in pp collisions at root s=7 TeV

0510215 - ÚJF 2020 RIV US eng J - Článek v odborném periodiku
Acharya, S. - Adamová, Dagmar - Bielčík, J. - Bielčíková, Jana - Broz, M. - Contreras, J. G. - Křížková Gajdošová, K. - Horák, D. - Křížek, Filip - Kučera, Vít - Kushpil, Svetlana - Lavička, R. - Mareš, Jiří A. - Petráček, V. - Šumbera, Michal - Závada, Petr … celkem 1016 autorů
Event-shape and multiplicity dependence of freeze-out radii in pp collisions at root s=7 TeV.
Journal of High Energy Physics. Roč. 2019, č. 9 (2019), č. článku 108. ISSN 1029-8479. E-ISSN 1029-8479
Grant CEP: GA MŠMT(CZ) LTT17018
Výzkumná infrastruktura: CERN-CZ - 90058
Institucionální podpora: RVO:68378271 ; RVO:61389005
Klíčová slova: ALICE collaboration * heavy ion experiments * particle correlations and fluctuations
Obor OECD: Nuclear physics; Particles and field physics (FZU-D)
Impakt faktor: 5.875, rok: 2019
Způsob publikování: Open access
https://doi.org/10.1007/JHEP09(2019)108

Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q proportional to 1/R. It was previously observed that in pp collisions at root s = 7 TeV the average pair transverse momentum k(T) range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity S-T into spherical (S-T > 0.7) and jet-like (S-T < 0.3) events a method was developed that allows for the determination of source radii for much larger values of k(T) for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the k(T) dependence of the radii. The emission source size in spherical events shows a substantially diminished k(T) dependence, while jet-like events show indications of a negative trend with respect to k(T) in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one.
Trvalý link: http://hdl.handle.net/11104/0300744