Global polarization of Λ hyperons in Au + Au collisions at sNN =200 GeV

STAR Collaboration

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percentage in Au+Au collisions at sNN = 200 GeV, with no significant difference between Λ and Λ. These new results reveal the collision energy dependence of the global polarization together with the results previously observed at sNN = 7.7-62.4 GeV and indicate noticeable vorticity of the medium created in noncentral heavy-ion collisions at the highest Relativistic Heavy Ion Collider collision energy. The signal is in rough quantitative agreement with the theoretical predictions from a hydrodynamic model and from a multi-phase transport model. The polarization is larger in more peripheral collisions, and depends weakly on the hyperon's transverse momentum and pseudorapidity ηH within |ηH|<1. An indication of the polarization dependence on the event-by-event charge asymmetry is observed at the 2σ level, suggesting a possible contribution to the polarization from the axial current induced by the initial magnetic field.

Original languageEnglish (US)
Article number014910
JournalPhysical Review C
Volume98
Issue number1
DOIs
StatePublished - Jul 23 2018

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hyperons
collisions
polarization
transverse momentum
ionic collisions
vorticity
heavy ions
indication
hydrodynamics
asymmetry
energy
predictions
magnetic fields

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

Cite this

Global polarization of Λ hyperons in Au + Au collisions at sNN =200 GeV. / STAR Collaboration.

In: Physical Review C, Vol. 98, No. 1, 014910, 23.07.2018.

Research output: Contribution to journalArticle

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title = "Global polarization of Λ hyperons in Au + Au collisions at sNN =200 GeV",
abstract = "Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percentage in Au+Au collisions at sNN = 200 GeV, with no significant difference between Λ and Λ. These new results reveal the collision energy dependence of the global polarization together with the results previously observed at sNN = 7.7-62.4 GeV and indicate noticeable vorticity of the medium created in noncentral heavy-ion collisions at the highest Relativistic Heavy Ion Collider collision energy. The signal is in rough quantitative agreement with the theoretical predictions from a hydrodynamic model and from a multi-phase transport model. The polarization is larger in more peripheral collisions, and depends weakly on the hyperon's transverse momentum and pseudorapidity ηH within |ηH|<1. An indication of the polarization dependence on the event-by-event charge asymmetry is observed at the 2σ level, suggesting a possible contribution to the polarization from the axial current induced by the initial magnetic field.",
author = "{STAR Collaboration} and J. Adam and L. Adamczyk and Adams, {J. R.} and Adkins, {J. K.} and G. Agakishiev and Aggarwal, {M. M.} and Z. Ahammed and Ajitanand, {N. N.} and I. Alekseev and Anderson, {D. M.} and R. Aoyama and A. Aparin and D. Arkhipkin and Aschenauer, {E. C.} and Ashraf, {M. U.} and F. Atetalla and A. Attri and Averichev, {G. S.} and X. Bai and V. Bairathi and K. Barish and Bassill, {A. J.} and A. Behera and R. Bellwied and A. Bhasin and Bhati, {A. K.} and J. Bielcik and J. Bielcikova and Bland, {L. C.} and Bordyuzhin, {I. G.} and Brandenburg, {J. D.} and Brandin, {A. V.} and D. Brown and J. Bryslawskyj and I. Bunzarov and J. Butterworth and H. Caines and {Calder{\'o}n De La Barca S{\'a}nchez}, M. and Campbell, {J. M.} and D. Cebra and I. Chakaberia and P. Chaloupka and Chang, {F. H.} and Z. Chang and N. Chankova-Bunzarova and A. Chatterjee and S. Chattopadhyay and Chen, {J. H.} and Cherney, {Michael G.} and Seger, {Janet E.}",
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AU - STAR Collaboration

AU - Adam, J.

AU - Adamczyk, L.

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AU - Adkins, J. K.

AU - Agakishiev, G.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

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AU - Attri, A.

AU - Averichev, G. S.

AU - Bai, X.

AU - Bairathi, V.

AU - Barish, K.

AU - Bassill, A. J.

AU - Behera, A.

AU - Bellwied, R.

AU - Bhasin, A.

AU - Bhati, A. K.

AU - Bielcik, J.

AU - Bielcikova, J.

AU - Bland, L. C.

AU - Bordyuzhin, I. G.

AU - Brandenburg, J. D.

AU - Brandin, A. V.

AU - Brown, D.

AU - Bryslawskyj, J.

AU - Bunzarov, I.

AU - Butterworth, J.

AU - Caines, H.

AU - Calderón De La Barca Sánchez, M.

AU - Campbell, J. M.

AU - Cebra, D.

AU - Chakaberia, I.

AU - Chaloupka, P.

AU - Chang, F. H.

AU - Chang, Z.

AU - Chankova-Bunzarova, N.

AU - Chatterjee, A.

AU - Chattopadhyay, S.

AU - Chen, J. H.

AU - Cherney, Michael G.

AU - Seger, Janet E.

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N2 - Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percentage in Au+Au collisions at sNN = 200 GeV, with no significant difference between Λ and Λ. These new results reveal the collision energy dependence of the global polarization together with the results previously observed at sNN = 7.7-62.4 GeV and indicate noticeable vorticity of the medium created in noncentral heavy-ion collisions at the highest Relativistic Heavy Ion Collider collision energy. The signal is in rough quantitative agreement with the theoretical predictions from a hydrodynamic model and from a multi-phase transport model. The polarization is larger in more peripheral collisions, and depends weakly on the hyperon's transverse momentum and pseudorapidity ηH within |ηH|<1. An indication of the polarization dependence on the event-by-event charge asymmetry is observed at the 2σ level, suggesting a possible contribution to the polarization from the axial current induced by the initial magnetic field.

AB - Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percentage in Au+Au collisions at sNN = 200 GeV, with no significant difference between Λ and Λ. These new results reveal the collision energy dependence of the global polarization together with the results previously observed at sNN = 7.7-62.4 GeV and indicate noticeable vorticity of the medium created in noncentral heavy-ion collisions at the highest Relativistic Heavy Ion Collider collision energy. The signal is in rough quantitative agreement with the theoretical predictions from a hydrodynamic model and from a multi-phase transport model. The polarization is larger in more peripheral collisions, and depends weakly on the hyperon's transverse momentum and pseudorapidity ηH within |ηH|<1. An indication of the polarization dependence on the event-by-event charge asymmetry is observed at the 2σ level, suggesting a possible contribution to the polarization from the axial current induced by the initial magnetic field.

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