Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions
Apstrakt
The technique of two-particle correlations has been widely used in studying flow via azimuthal anisotropy in relativistic heavy-ion collisions. A key assumption imposed in this approach is the factorization of Fourier coefficients extracted from two-particle correlations into a product of single-particle anisotropies of trigger and associated particles. It was recently predicted by hydrodynamics that due to initial-state participant fluctuations, a transverse momentum (p(T)) dependence of the event-plane angle would be induced, leading to a breakdown of factorization, even if hydrodynamic flow is the only source of correlations. We present a systematic examination of the factorization assumption in pPb and PbPb collisions at a nucleon nucleon center-of-mass energy of 5.02 TeV and 2.76 TeV, respectively, with the CMS experiment. Significant breakdown of factorization (up to 20%) is observed in a large sample of ultra-central (0-0.2%) triggered PbPb events, where initial-state fluctuatio...ns play a dominant role. Comparison of data and viscous hydrodynamic predictions, as a function of p(T) and centrality, allows new constraints on the modeling of initial condition and shear viscosity to entropy density (eta/s) ratio of the medium created in heavy-ion collisions. Furthermore, the measurement is also extended to high-multiplicity pPb collisions. As the initial-state geometry of a pPb collision is expected to be entirely a consequence of fluctuations, quantitative studies of factorization breakdown will help to investigate the nature of the observed long-range correlations in pPb collisions, particularly in the context of hydrodynamic models. (C) 2014 CERN. Published by Elsevier B.V. All rights reserved.
Ključne reči:
Dihadron correlations / Factorization / Initial state fluctuationsIzvor:
Nuclear Physics A, 2014, 931, 954-958
DOI: 10.1016/j.nuclphysa.2014.10.017
ISSN: 0375-9474; 1873-1554
WoS: 000347598500152
Scopus: 2-s2.0-84922343189
Kolekcije
Institucija/grupa
VinčaTY - JOUR AU - Devetak, Damir AU - CMS Collaboration PY - 2014 UR - https://vinar.vin.bg.ac.rs/handle/123456789/347 AB - The technique of two-particle correlations has been widely used in studying flow via azimuthal anisotropy in relativistic heavy-ion collisions. A key assumption imposed in this approach is the factorization of Fourier coefficients extracted from two-particle correlations into a product of single-particle anisotropies of trigger and associated particles. It was recently predicted by hydrodynamics that due to initial-state participant fluctuations, a transverse momentum (p(T)) dependence of the event-plane angle would be induced, leading to a breakdown of factorization, even if hydrodynamic flow is the only source of correlations. We present a systematic examination of the factorization assumption in pPb and PbPb collisions at a nucleon nucleon center-of-mass energy of 5.02 TeV and 2.76 TeV, respectively, with the CMS experiment. Significant breakdown of factorization (up to 20%) is observed in a large sample of ultra-central (0-0.2%) triggered PbPb events, where initial-state fluctuations play a dominant role. Comparison of data and viscous hydrodynamic predictions, as a function of p(T) and centrality, allows new constraints on the modeling of initial condition and shear viscosity to entropy density (eta/s) ratio of the medium created in heavy-ion collisions. Furthermore, the measurement is also extended to high-multiplicity pPb collisions. As the initial-state geometry of a pPb collision is expected to be entirely a consequence of fluctuations, quantitative studies of factorization breakdown will help to investigate the nature of the observed long-range correlations in pPb collisions, particularly in the context of hydrodynamic models. (C) 2014 CERN. Published by Elsevier B.V. All rights reserved. T2 - Nuclear Physics A T1 - Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions VL - 931 SP - 954 EP - 958 DO - 10.1016/j.nuclphysa.2014.10.017 ER -
@article{ author = "Devetak, Damir and CMS Collaboration", year = "2014", abstract = "The technique of two-particle correlations has been widely used in studying flow via azimuthal anisotropy in relativistic heavy-ion collisions. A key assumption imposed in this approach is the factorization of Fourier coefficients extracted from two-particle correlations into a product of single-particle anisotropies of trigger and associated particles. It was recently predicted by hydrodynamics that due to initial-state participant fluctuations, a transverse momentum (p(T)) dependence of the event-plane angle would be induced, leading to a breakdown of factorization, even if hydrodynamic flow is the only source of correlations. We present a systematic examination of the factorization assumption in pPb and PbPb collisions at a nucleon nucleon center-of-mass energy of 5.02 TeV and 2.76 TeV, respectively, with the CMS experiment. Significant breakdown of factorization (up to 20%) is observed in a large sample of ultra-central (0-0.2%) triggered PbPb events, where initial-state fluctuations play a dominant role. Comparison of data and viscous hydrodynamic predictions, as a function of p(T) and centrality, allows new constraints on the modeling of initial condition and shear viscosity to entropy density (eta/s) ratio of the medium created in heavy-ion collisions. Furthermore, the measurement is also extended to high-multiplicity pPb collisions. As the initial-state geometry of a pPb collision is expected to be entirely a consequence of fluctuations, quantitative studies of factorization breakdown will help to investigate the nature of the observed long-range correlations in pPb collisions, particularly in the context of hydrodynamic models. (C) 2014 CERN. Published by Elsevier B.V. All rights reserved.", journal = "Nuclear Physics A", title = "Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions", volume = "931", pages = "954-958", doi = "10.1016/j.nuclphysa.2014.10.017" }
Devetak, D.,& CMS Collaboration. (2014). Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions. in Nuclear Physics A, 931, 954-958. https://doi.org/10.1016/j.nuclphysa.2014.10.017
Devetak D, CMS Collaboration. Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions. in Nuclear Physics A. 2014;931:954-958. doi:10.1016/j.nuclphysa.2014.10.017 .
Devetak, Damir, CMS Collaboration, "Probing initial-state fluctuations with p(T)-dependent event-plane angle in pPb and PbPb collisions" in Nuclear Physics A, 931 (2014):954-958, https://doi.org/10.1016/j.nuclphysa.2014.10.017 . .