This Letter presents a measurement of γγ→μ+μ- production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at sNN=5.02  TeV with an integrated luminosity of 0.49  nb-1. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from γγ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultraperipheral collisions. The angular correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with rescattering of the muons while passing through the hot matter produced in the collision.

Observation of Centrality-Dependent Acoplanarity for Muon Pairs Produced via Two-Photon Scattering in Pb+Pb Collisions at sNN =5.02 TeV with the ATLAS Detector

Farina E. M.;Fraternali M.;Introzzi G.;Livan M.;Negri A.;Rebuzzi D. M.;Rimoldi A.;Sottocornola S.;
2018-01-01

Abstract

This Letter presents a measurement of γγ→μ+μ- production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at sNN=5.02  TeV with an integrated luminosity of 0.49  nb-1. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from γγ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultraperipheral collisions. The angular correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with rescattering of the muons while passing through the hot matter produced in the collision.
2018
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Esperti anonimi
Inglese
Internazionale
STAMPA
121
21
212301
Particle physics, High energy physics
http://harvest.aps.org/bagit/articles/10.1103/PhysRevLett.121.212301/apsxml
2916
info:eu-repo/semantics/article
262
Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B.; Abhayasinghe, D. K.; Abidi, S. H.; Abouzeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1271886
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