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Abstract: Charge-dependent azimuthal correlations of same- and opposite-sign pairs with respect to the second- and third-order event planes have been measured in pPb collisions at sNN=8.16TeV and PbPb collisions at 5.02 TeV with the CMS experiment at the LHC. The measurement is motivated by the search for the charge separation phenomenon predicted by the chiral magnetic effect (CME) in heavy ion collisions. Three- and two-particle azimuthal correlators are extracted as functions of the pseudorapidity difference, the transverse momentum (pT) difference, and the pT average of same- and opposite-charge pairs in various event multiplicity ranges. The data suggest that the charge-dependent three-particle correlators with respect to the second- and third-order event planes share a common origin, predominantly arising from charge-dependent two-particle azimuthal correlations coupled with an anisotropic flow. The CME is expected to lead to a v2-independent three-particle correlation when the magnetic field is fixed. Using an event shape engineering technique, upper limits on the v2-independent fraction of the three-particle correlator are estimated to be 13% for pPb and 7% for PbPb collisions at 95% confidence level. The results of this analysis, both the dominance of two-particle correlations as a source of the three-particle results and the similarities seen between PbPb and pPb, provide stringent constraints on the origin of charge-dependent three-particle azimuthal correlations and challenge their interpretation as arising from a chiral magnetic effect in heavy ion collisions.
Fuente: Phys. Rev. C, Vol. 97, Num. 4, Pag. 044912 (2018)
Publisher: American Physical Society
Publication date: 23/04/2018
No. of pages: 34
Publication type: Article
DOI: 10.1103/PhysRevC.97.044912
ISSN: 0556-2813,1089-490X,2469-9985,2469-9993
Publication Url: https://doi.org/10.1103/PhysRevC.97.044912
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SIRUNYAN, A. M.
JOSE IBAN CABRILLO BARTOLOME
ALICIA CALDERON TAZON
BARBARA CHAZIN QUERO
ESTEBAN CURRAS RIVERA
JORGE DUARTE CAMPDERROS
MARCOS FERNANDEZ GARCIA
JUAN GARCIA FERRERO
GERVASIO GOMEZ GRAMUGLIO
MARIA AMPARO LOPEZ VIRTO
JESUS MARCO DE LUCAS
CELSO MARTINEZ RIVERO
PABLO MARTINEZ RUIZ DEL ARBOL
FRANCISCO MATORRAS WEINIG
JONATAN PIEDRA GOMEZ
MARIA TERESA RODRIGO ANORO
ALBERTO RUIZ JIMENO
LUCA SCODELLARO
NICOLO TREVISANI
IVAN VILA ALVAREZ
ROCIO VILAR CORTABITARTE
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