Azimuthal anisotropy in Cu+Au collisions at s NN =200 GeV

STAR Collaboration, L. Adamczyk, J. R. Adams, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish & 31 others A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, J. Bryslawskyj, I. Bunzarov, J. Butterworth, H. Caines, M. Calderón De La Barca Sánchez, J. M. Campbell, D. Cebra, I. Chakaberia, P. Chaloupka, Z. Chang, N. Chankova-Bunzarova, A. Chatterjee, S. Chattopadhyay, X. Chen, J. H. Chen, X. Chen, Michael G. Cherney, Janet E. Seger

Research output: Contribution to journalArticle

Abstract

The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at sNN=200 GeV for harmonics n=1-4 in the pseudorapidity range |η|<1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at sNN=200 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane (px) in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept at about η≈-0.4 (shifted from zero in the Au-going direction), closer to the rapidity of the Cu+Au system center of mass. The observed dependencies find a natural explanation in a picture of the directed flow originating partly due the "tilted source" and partly due to the asymmetry in the initial density distribution. A charge dependence of (px) was also observed in Cu+Au collisions, consistent with an effect of the initial electric field created by charge difference of the spectator protons in two colliding nuclei. The rapidity-even component of directed flow in Au+Au collisions is close to that in Pb+Pb collisions at sNN=2.76 TeV, indicating a similar magnitude of dipolelike fluctuations in the initial-state density distribution. Higher harmonic flow in Cu+Au collisions exhibits similar trends to those observed in Au+Au and Pb+Pb collisions and is qualitatively reproduced by a viscous hydrodynamic model and a multiphase transport model. For all harmonics with n≥2 we observe an approximate scaling of vn with the number of constituent quarks; this scaling works as well in Cu+Au collisions as it does in Au+Au collisions.

LanguageEnglish (US)
Article number014915
JournalPhysical Review C
Volume98
Issue number1
DOIs
StatePublished - Jul 31 2018

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anisotropy
collisions
harmonics
density distribution
charged particles
scaling
transverse momentum
center of mass
hydrodynamics
asymmetry
quarks
slopes
trends
nuclei
protons
electric fields

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

Cite this

Azimuthal anisotropy in Cu+Au collisions at s NN =200 GeV. / STAR Collaboration.

In: Physical Review C, Vol. 98, No. 1, 014915, 31.07.2018.

Research output: Contribution to journalArticle

STAR Collaboration. / Azimuthal anisotropy in Cu+Au collisions at s NN =200 GeV. In: Physical Review C. 2018 ; Vol. 98, No. 1.
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abstract = "The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at sNN=200 GeV for harmonics n=1-4 in the pseudorapidity range |η|<1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at sNN=200 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane (px) in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept at about η≈-0.4 (shifted from zero in the Au-going direction), closer to the rapidity of the Cu+Au system center of mass. The observed dependencies find a natural explanation in a picture of the directed flow originating partly due the {"}tilted source{"} and partly due to the asymmetry in the initial density distribution. A charge dependence of (px) was also observed in Cu+Au collisions, consistent with an effect of the initial electric field created by charge difference of the spectator protons in two colliding nuclei. The rapidity-even component of directed flow in Au+Au collisions is close to that in Pb+Pb collisions at sNN=2.76 TeV, indicating a similar magnitude of dipolelike fluctuations in the initial-state density distribution. Higher harmonic flow in Cu+Au collisions exhibits similar trends to those observed in Au+Au and Pb+Pb collisions and is qualitatively reproduced by a viscous hydrodynamic model and a multiphase transport model. For all harmonics with n≥2 we observe an approximate scaling of vn with the number of constituent quarks; this scaling works as well in Cu+Au collisions as it does in Au+Au collisions.",
author = "{STAR Collaboration} 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 A. Attri and Averichev, {G. S.} and X. Bai and V. Bairathi and K. Barish and A. Behera and R. Bellwied and A. Bhasin and Bhati, {A. K.} and P. Bhattarai and J. Bielcik and J. Bielcikova and Bland, {L. C.} and Bordyuzhin, {I. G.} and J. Bouchet 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 Z. Chang and N. Chankova-Bunzarova and A. Chatterjee and S. Chattopadhyay and X. Chen and Chen, {J. H.} and X. Chen and Cherney, {Michael G.} and Seger, {Janet E.}",
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T1 - Azimuthal anisotropy in Cu+Au collisions at s NN =200 GeV

AU - STAR Collaboration

AU - Adamczyk, L.

AU - Adams, J. R.

AU - Adkins, J. K.

AU - Agakishiev, G.

AU - Aggarwal, M. M.

AU - Ahammed, Z.

AU - Ajitanand, N. N.

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 - Attri, A.

AU - Averichev, G. S.

AU - Bai, X.

AU - Bairathi, V.

AU - Barish, K.

AU - Behera, A.

AU - Bellwied, R.

AU - Bhasin, A.

AU - Bhati, A. K.

AU - Bhattarai, P.

AU - Bielcik, J.

AU - Bielcikova, J.

AU - Bland, L. C.

AU - Bordyuzhin, I. G.

AU - Bouchet, J.

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, Z.

AU - Chankova-Bunzarova, N.

AU - Chatterjee, A.

AU - Chattopadhyay, S.

AU - Chen, X.

AU - Chen, J. H.

AU - Chen, X.

AU - Cherney, Michael G.

AU - Seger, Janet E.

PY - 2018/7/31

Y1 - 2018/7/31

N2 - The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at sNN=200 GeV for harmonics n=1-4 in the pseudorapidity range |η|<1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at sNN=200 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane (px) in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept at about η≈-0.4 (shifted from zero in the Au-going direction), closer to the rapidity of the Cu+Au system center of mass. The observed dependencies find a natural explanation in a picture of the directed flow originating partly due the "tilted source" and partly due to the asymmetry in the initial density distribution. A charge dependence of (px) was also observed in Cu+Au collisions, consistent with an effect of the initial electric field created by charge difference of the spectator protons in two colliding nuclei. The rapidity-even component of directed flow in Au+Au collisions is close to that in Pb+Pb collisions at sNN=2.76 TeV, indicating a similar magnitude of dipolelike fluctuations in the initial-state density distribution. Higher harmonic flow in Cu+Au collisions exhibits similar trends to those observed in Au+Au and Pb+Pb collisions and is qualitatively reproduced by a viscous hydrodynamic model and a multiphase transport model. For all harmonics with n≥2 we observe an approximate scaling of vn with the number of constituent quarks; this scaling works as well in Cu+Au collisions as it does in Au+Au collisions.

AB - The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at sNN=200 GeV for harmonics n=1-4 in the pseudorapidity range |η|<1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at sNN=200 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane (px) in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept at about η≈-0.4 (shifted from zero in the Au-going direction), closer to the rapidity of the Cu+Au system center of mass. The observed dependencies find a natural explanation in a picture of the directed flow originating partly due the "tilted source" and partly due to the asymmetry in the initial density distribution. A charge dependence of (px) was also observed in Cu+Au collisions, consistent with an effect of the initial electric field created by charge difference of the spectator protons in two colliding nuclei. The rapidity-even component of directed flow in Au+Au collisions is close to that in Pb+Pb collisions at sNN=2.76 TeV, indicating a similar magnitude of dipolelike fluctuations in the initial-state density distribution. Higher harmonic flow in Cu+Au collisions exhibits similar trends to those observed in Au+Au and Pb+Pb collisions and is qualitatively reproduced by a viscous hydrodynamic model and a multiphase transport model. For all harmonics with n≥2 we observe an approximate scaling of vn with the number of constituent quarks; this scaling works as well in Cu+Au collisions as it does in Au+Au collisions.

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