Polarization of Λ (Λ ̄) Hyperons along the Beam Direction in Au+Au Collisions at sNN =200 GeV

doi:10.1103/PhysRevLett.123.132301

Polarization of Λ (Λ ̄) Hyperons along the Beam Direction in Au+Au Collisions at sNN =200 GeV

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Abstract

The Λ (Λ̄) hyperon polarization along the beam direction has been measured in Au+Au collisions at sNN=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (pT) dependence at pT greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown-Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.

Original language	English
Article number	132301
Journal	Physical Review Letters
Volume	123
Issue number	13
DOIs	https://doi.org/10.1103/PhysRevLett.123.132301
State	Published - Sep 27 2019

Bibliographical note

Publisher Copyright:
© 2019 American Physical Society.

Funding

We thank the RHIC Operations Group and RCF at BNL, the NERSC Center at LBNL, and the Open Science Grid consortium for providing resources and support. This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science, the U.S. National Science Foundation, the Ministry of Education and Science of the Russian Federation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia, RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF) and the Helmholtz Association.

Funders	Funder number
Hungarian Ministry of Human Capacities
National Research Foundation of Korea
Max Delbrück Center for Molecular Medicine in the Helmholtz Association
Ministry of Education of the People's Republic of China
Narodowe Centrum Nauki
Grantová Agentura České Republiky
Bundesministerium für Bildung und Forschung
Nemzeti Kutatási Fejlesztési és Innovációs Hivatal
Ministry for Education and Science of the Russian Federation
RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie
Ministry of Science and Technology of the People's Republic of China
Department of Atomic Energy and Department of Science and Technology
Ministarstvo Obrazovanja, Znanosti i Sporta
Chinese Academy of Sciences
National Science Foundation Office of International Science and Engineering
Horia Hulubei National Institute for Physics and Nuclear Engineering
Ministerstvo Školství, Mládeže a Tělovýchovy
National Natural Science Foundation of China (NSFC)
Japan Society for the Promotion of Science Fund for the Promotion of Joint International Research	19H05598
Japan Society for the Promotion of Science Fund for the Promotion of Joint International Research
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	1913624
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China

ASJC Scopus subject areas

General Physics and Astronomy

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10.1103/PhysRevLett.123.132301

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@article{74337064a36d40c9baf4194612f963a7,

title = "Polarization of Λ (Λ{\= }) Hyperons along the Beam Direction in Au+Au Collisions at sNN =200 GeV",

abstract = "The Λ ({\=Λ}) hyperon polarization along the beam direction has been measured in Au+Au collisions at sNN=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (pT) dependence at pT greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown-Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.",

author = "J. Adam and L. Adamczyk and Adams, \{J. R.\} and Adkins, \{J. K.\} and G. Agakishiev and Aggarwal, \{M. M.\} and Z. Ahammed 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 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 J. Bryslawskyj and I. Bunzarov and J. Butterworth and H. Caines and \{Calder{\'o}n De La Barca S{\'a}nchez\}, M. and D. Cebra and I. Chakaberia and P. Chaloupka and Chan, \{B. K.\} and Chang, \{F. H.\} and Z. Chang and N. Chankova-Bunzarova and A. Chatterjee and S. Chattopadhyay and Chen, \{J. H.\} and X. Chen and J. Cheng and M. Cherney and W. Christie and R. Fatemi",

note = "Publisher Copyright: {\textcopyright} 2019 American Physical Society.",

year = "2019",

month = sep,

day = "27",

doi = "10.1103/PhysRevLett.123.132301",

language = "English",

volume = "123",

number = "13",

}

TY - JOUR

T1 - Polarization of Λ (Λ ̄) Hyperons along the Beam Direction in Au+Au Collisions at sNN =200 GeV

AU - Adam, J.

AU - Adamczyk, L.

AU - Adams, J. R.

AU - Adkins, J. K.

AU - Agakishiev, G.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

AU - Alekseev, I.

AU - Anderson, D. M.

AU - Aoyama, R.

AU - Aparin, A.

AU - Arkhipkin, D.

AU - Aschenauer, E. C.

AU - Ashraf, M. U.

AU - Atetalla, F.

AU - Attri, A.

AU - Averichev, G. S.

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 - Bryslawskyj, J.

AU - Bunzarov, I.

AU - Butterworth, J.

AU - Caines, H.

AU - Calderón De La Barca Sánchez, M.

AU - Cebra, D.

AU - Chakaberia, I.

AU - Chaloupka, P.

AU - Chan, B. K.

AU - Chang, F. H.

AU - Chang, Z.

AU - Chankova-Bunzarova, N.

AU - Chatterjee, A.

AU - Chattopadhyay, S.

AU - Chen, J. H.

AU - Chen, X.

AU - Cheng, J.

AU - Cherney, M.

AU - Christie, W.

AU - Fatemi, R.

PY - 2019/9/27

Y1 - 2019/9/27

N2 - The Λ (Λ̄) hyperon polarization along the beam direction has been measured in Au+Au collisions at sNN=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (pT) dependence at pT greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown-Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.

AB - The Λ (Λ̄) hyperon polarization along the beam direction has been measured in Au+Au collisions at sNN=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (pT) dependence at pT greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown-Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.

UR - https://www.scopus.com/pages/publications/85072781702

UR - https://www.scopus.com/pages/publications/85072781702#tab=citedBy

U2 - 10.1103/PhysRevLett.123.132301

DO - 10.1103/PhysRevLett.123.132301

M3 - Article

C2 - 31697517

AN - SCOPUS:85072781702

SN - 0031-9007

VL - 123

JO - Physical Review Letters

JF - Physical Review Letters

IS - 13

M1 - 132301

ER -

Polarization of Λ (Λ ̄) Hyperons along the Beam Direction in Au+Au Collisions at sNN =200 GeV

Abstract

Bibliographical note

Funding

ASJC Scopus subject areas

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