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Title: Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions.

Abstract

Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2];  [2];  [2];  [2];  [2]
  1. (High Energy Physics)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF); Soan Foundation; EPSRC - United Kingdom
OSTI Identifier:
1050167
Report Number(s):
ANL-HEP-CP-10-34
Journal ID: ISSN 0556-2813; PRVCAN; TRN: US1204547
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Physical Review, C (Nuclear Physics)
Additional Journal Information:
Journal Volume: 81; Journal Issue: 5; Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
ENGLISH
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HEAVY IONS; PARITY; PARTICLE RAPIDITY; QUANTUM CHROMODYNAMICS; QUARKS; STARS; TRANSVERSE MOMENTUM; ION COLLISIONS

Citation Formats

Abelev, B. I., Aggarwal, M. M., Ahammed, Z., Alakhverdyants, A. V., Anderson, B. D., Bridgeman, A., Krueger, K., Spinka, H. M., Underwood, D. G., STAR Collaboration, Univ. of Illinois at Chicago), Panjab Univ.), Variable Energy Cyclotron Centre), Kent State Univ.), and Univ. of Kentucky). Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions.. United States: N. p., 2010. Web. doi:10.1103/PhysRevC.81.054908.
Abelev, B. I., Aggarwal, M. M., Ahammed, Z., Alakhverdyants, A. V., Anderson, B. D., Bridgeman, A., Krueger, K., Spinka, H. M., Underwood, D. G., STAR Collaboration, Univ. of Illinois at Chicago), Panjab Univ.), Variable Energy Cyclotron Centre), Kent State Univ.), & Univ. of Kentucky). Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions.. United States. doi:10.1103/PhysRevC.81.054908.
Abelev, B. I., Aggarwal, M. M., Ahammed, Z., Alakhverdyants, A. V., Anderson, B. D., Bridgeman, A., Krueger, K., Spinka, H. M., Underwood, D. G., STAR Collaboration, Univ. of Illinois at Chicago), Panjab Univ.), Variable Energy Cyclotron Centre), Kent State Univ.), and Univ. of Kentucky). Fri . "Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions.". United States. doi:10.1103/PhysRevC.81.054908.
@article{osti_1050167,
title = {Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions.},
author = {Abelev, B. I. and Aggarwal, M. M. and Ahammed, Z. and Alakhverdyants, A. V. and Anderson, B. D. and Bridgeman, A. and Krueger, K. and Spinka, H. M. and Underwood, D. G. and STAR Collaboration and Univ. of Illinois at Chicago) and Panjab Univ.) and Variable Energy Cyclotron Centre) and Kent State Univ.) and Univ. of Kentucky)},
abstractNote = {Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.},
doi = {10.1103/PhysRevC.81.054908},
journal = {Physical Review, C (Nuclear Physics)},
issn = {0556-2813},
number = 5,
volume = 81,
place = {United States},
year = {2010},
month = {1}
}