Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions

A systematic study of the factorization of long-range azimuthal two-particle correlations into a product of single-particle anisotropies is presented as a function of pT and η of both particles and as a function of the particle multiplicity in PbPb and pPb collisions. The data were taken with the CMS detector for PbPb collisions at sNN=2.76 TeV and pPb collisions at sNN=5.02 TeV, covering a very wide range of multiplicity. Factorization is observed to be broken as a function of both particle pT and η. When measured with particles of different pT, the magnitude of the factorization breakdown for the second Fourier harmonic reaches 20% for very central PbPb collisions but decreases rapidly as the multiplicity decreases. The data are consistent with viscous hydrodynamic predictions, which suggest that the effect of factorization breaking is mainly sensitive to the initial-state conditions rather than to the transport properties (e.g., shear viscosity) of the medium. The factorization breakdown is also computed with particles of different η. The effect is found to be weakest for mid-central PbPb events but becomes larger for more central or peripheral PbPb collisions, and also for very-high-multiplicity pPb collisions. The η-dependent factorization data provide new insights to the longitudinal evolution of the medium formed in heavy ion collisions.

Note:

Replaced with published version. Added journal reference and DOI

25.75.Gz
25.75.Dw
multiplicity: dependence
angular correlation: two-particle
hydrodynamics: viscosity
heavy ion: scattering
factorization: violation
transverse momentum: dependence
transport theory
initial state: fluctuation

References(48)

Figures(13)

[1]

Quark gluon plasma and color glass condensate at RHIC? The Perspective from the BRAHMS experiment

BRAHMS

Collaboration

•

I. Arsene
(
- Bucharest U.
)

et al.

- Nucl.Phys.A 757 (2005) 1-27
•
e-Print:
- nucl-ex/0410020
•
DOI:
- 10.1016/j.nuclphysa.2005.02.130

[2]

The PHOBOS perspective on discoveries at RHIC

PHOBOS

Collaboration

•

B.B. Back
(
- Argonne
)

et al.

- Nucl.Phys.A 757 (2005) 28-101
•
e-Print:
- nucl-ex/0410022
•
DOI:
- 10.1016/j.nuclphysa.2005.03.084

[3]

Experimental and theoretical challenges in the search for the quark gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions

STAR

Collaboration

•

John Adams
(
- Birmingham U.
)

et al.

- Nucl.Phys.A 757 (2005) 102-183
•
e-Print:
- nucl-ex/0501009
•
DOI:
- 10.1016/j.nuclphysa.2005.03.085

[4]

Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration

PHENIX

Collaboration

•

K. Adcox
(
- Vanderbilt U.
)

et al.

- Nucl.Phys.A 757 (2005) 184-283
•
e-Print:
- nucl-ex/0410003
•
DOI:
- 10.1016/j.nuclphysa.2005.03.086

[5]

Harmonic decomposition of two-particle angular correlations in Pb-Pb collisions at $\sqrt{s_{NN}}=$ 2.76 TeV

ALICE

Collaboration

•

K. Aamodt
(
- Bergen U.
)

et al.

- Phys.Lett.B 708 (2012) 249-264
•
e-Print:
- 1109.2501
•
DOI:
- 10.1016/j.physletb.2012.01.060

[6]

Elliptic flow of identified hadrons in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV

ALICE

Collaboration

•

Betty Bezverkhny Abelev
(
- LLNL, Livermore
)

et al.

- JHEP 06 (2015) 190
•
e-Print:
- 1405.4632
•
DOI:
- 10.1007/JHEP06(2015)190

[7]

Measurement of the azimuthal anisotropy for charged particle production in $\sqrt{s_{NN}}=2.76$ TeV lead-lead collisions with the ATLAS detector

ATLAS

Collaboration

•

Georges Aad
(
- Freiburg U.
)

et al.

- Phys.Rev.C 86 (2012) 014907
•
e-Print:
- 1203.3087
•
DOI:
- 10.1103/PhysRevC.86.014907

[8]

Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at = 2.76 TeV with the ATLAS detector at the LHC

ATLAS

Collaboration

•

Georges Aad
(
- Freiburg U.
)

et al.

- JHEP 11 (2013) 183
•
e-Print:
- 1305.2942
•
DOI:
- 10.1007/JHEP11(2013)183

[9]

Measurement of event-plane correlations in $\sqrt{s_{NN}}=2.76$ TeV lead-lead collisions with the ATLAS detector

ATLAS

Collaboration

•

Georges Aad
(
- Marseille, CPPM
)

et al.

- Phys.Rev.C 90 (2014) 2, 024905
•
e-Print:
- 1403.0489
•
DOI:
- 10.1103/PhysRevC.90.024905

[10]

Centrality Dependence of Dihadron Correlations and Azimuthal anisotropy Harmonics in PbPb Collisions at $\sqrt{s_{NN}}=2.76$ TeV

CMS

Collaboration

•

Serguei Chatrchyan
(
- Yerevan Phys. Inst.
)

et al.

- Eur.Phys.J.C 72 (2012) 2012
•
e-Print:
- 1201.3158
•
DOI:
- 10.1140/epjc/s10052-012-2012-3

[11]

Measurement of the Elliptic Anisotropy of Charged Particles Produced in PbPb Collisions at $\sqrt{s}_{NN}$ =2.76 TeV

CMS

Collaboration

•

Serguei Chatrchyan
(
- Yerevan Phys. Inst.
)

et al.

- Phys.Rev.C 87 (2013) 1, 014902
•
e-Print:
- 1204.1409
•
DOI:
- 10.1103/PhysRevC.87.014902

[12]

Measurement of Higher-Order Harmonic Azimuthal Anisotropy in PbPb Collisions at $\sqrt{s_{NN}}$ = 2.76 TeV

CMS

Collaboration

•

Serguei Chatrchyan
(
- Yerevan Phys. Inst.
)

et al.

- Phys.Rev.C 89 (2014) 4, 044906
•
e-Print:
- 1310.8651
•
DOI:
- 10.1103/PhysRevC.89.044906

[13]

Studies of Azimuthal Dihadron Correlations in Ultra-Central PbPb Collisions at $\sqrt{s_{NN}} =$ 2.76 TeV

CMS

Collaboration

•

Serguei Chatrchyan
(
- Yerevan Phys. Inst.
)

et al.

- JHEP 02 (2014) 088
•
e-Print:
- 1312.1845
•
DOI:
- 10.1007/JHEP02(2014)088

[14]

Determination of the reaction plane in ultrarelativistic nuclear collisions

Jean-Yves Ollitrault
(
- Saclay
)

- Phys.Rev.D 48 (1993) 1132-1139
•
e-Print:
- hep-ph/9303247
•
DOI:
- 10.1103/PhysRevD.48.1132

[15]

Flow study in relativistic nuclear collisions by Fourier expansion of Azimuthal particle distributions

S. Voloshin
(
- Pittsburgh U.
)
,
Y. Zhang
(
- SUNY, Stony Brook
)

- Z.Phys.C 70 (1996) 665-672
•
e-Print:
- hep-ph/9407282
•
DOI:
- 10.1007/s002880050141

[16]

Methods for analyzing anisotropic flow in relativistic nuclear collisions

Arthur M. Poskanzer
(
- LBL, Berkeley
)
,
S.A. Voloshin
(
- Heidelberg U.
)

- Phys.Rev.C 58 (1998) 1671-1678
•
e-Print:
- nucl-ex/9805001
•
DOI:
- 10.1103/PhysRevC.58.1671

[17]

Collision geometry fluctuations and triangular flow in heavy-ion collisions

B. Alver
(
- MIT
)
,
G. Roland
(
- MIT
)

- Phys.Rev.C 81 (2010) 054905,
- Phys.Rev.C 82 (2010) 039903 (erratum)
•
e-Print:
- 1003.0194
•
DOI:
- 10.1103/PhysRevC.82.039903

[18]

Triangular flow in hydrodynamics and transport theory

- Phys.Rev.C 82 (2010) 034913
•
e-Print:
- 1007.5469
•
DOI:
- 10.1103/PhysRevC.82.034913

[19]

Elliptic and triangular flow in event-by-event (3+1)D viscous hydrodynamics

- Phys.Rev.Lett. 106 (2011) 042301
•
e-Print:
- 1009.3244
•
DOI:
- 10.1103/PhysRevLett.106.042301

[20]

Hydrodynamic elliptic and triangular flow in Pb-Pb collisions at $\sqrt{s}=2.76$ ATeV

- Phys.Lett.B 707 (2012) 151-155
•
e-Print:
- 1110.3033
•
DOI:
- 10.1016/j.physletb.2011.12.041

[21]

Transverse Momentum Analysis of Collective Motion in Relativistic Nuclear Collisions

P. Danielewicz
(
- LBL, Berkeley
)
,
G. Odyniec
(
- LBL, Berkeley
)

- Phys.Lett.B 157 (1985) 146-150,
- Lawrence Berkeley Lab. - LBL-18600 (84,REC.FEB.85) 14p,
- Phys. Lett. B157 (1985) 146-150 and Lawrence Berkeley Lab. - LBL-18600 (84,REC.FEB.85) 14p
•
e-Print:
- 2109.05308
•
DOI:
- 10.1016/0370-2693(85)91535-7