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Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb–Pb collisions at sNN=2.76 TeV

Acharya, S; Adam, J.; Adamova, D.; Adolfsson, Jonatan LU ; Aggarwal, M.M; Aglieri Rinella, G; Christiansen, Peter LU ; Oskarsson, Anders LU ; Richert, Tuva LU and Silvermyr, David LU , et al. (2018) In Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 777. p.151-162
Abstract
In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb–Pb collisions at sNN=2.76 TeV. The two-particle correlator 〈cos⁡(φα−φβ)〉 calculated for different combinations of charges α and β is almost independent of v2 (for a given centrality), while the three-particle correlator 〈cos⁡(φα+φβ−2Ψ2)〉 scales almost linearly both with the event v2 and charged-particle pseudorapidity density. The charge dependence... (More)
In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb–Pb collisions at sNN=2.76 TeV. The two-particle correlator 〈cos⁡(φα−φβ)〉 calculated for different combinations of charges α and β is almost independent of v2 (for a given centrality), while the three-particle correlator 〈cos⁡(φα+φβ−2Ψ2)〉 scales almost linearly both with the event v2 and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v2 points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10–50% centrality interval is found to be 26–33% at 95% confidence level. © 2017 The Author(s) (Less)
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Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
volume
777
pages
12 pages
publisher
Elsevier
external identifiers
  • scopus:85040798759
ISSN
0370-2693
DOI
10.1016/j.physletb.2017.12.021
language
English
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yes
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9ee2dbfc-064e-49b4-a55e-2e3569d61c48
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2018-01-30 07:38:22
date last changed
2018-02-04 04:35:08
@article{9ee2dbfc-064e-49b4-a55e-2e3569d61c48,
  abstract     = {In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb–Pb collisions at sNN=2.76 TeV. The two-particle correlator 〈cos⁡(φα−φβ)〉 calculated for different combinations of charges α and β is almost independent of v2 (for a given centrality), while the three-particle correlator 〈cos⁡(φα+φβ−2Ψ2)〉 scales almost linearly both with the event v2 and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v2 points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10–50% centrality interval is found to be 26–33% at 95% confidence level. © 2017 The Author(s)},
  author       = {Acharya, S and Adam, J. and Adamova, D. and Adolfsson, Jonatan and Aggarwal, M.M and Aglieri Rinella, G and Christiansen, Peter and Oskarsson, Anders and Richert, Tuva and Silvermyr, David and Stenlund, Evert and Vislavicius, Vytautas and , },
  issn         = {0370-2693},
  language     = {eng},
  pages        = {151--162},
  publisher    = {Elsevier},
  series       = {Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics},
  title        = {Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb–Pb collisions at sNN=2.76 TeV},
  url          = {http://dx.doi.org/10.1016/j.physletb.2017.12.021},
  volume       = {777},
  year         = {2018},
}