Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

Full text (en)

M. S. Borysova¹, Yu. O. Karpenko², Yu. M. Sinyukov<sup>2

1</sup>Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine
²M. M. Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kyiv, Ukraine

Abstract: The analysis of particle correlations as a function of relative pseudo-rapidity and azimuthal angle exhibit novel ridge-like structures that were discovered at RHIC in A + A collisions. Such an analysis is of great interest for forthcoming ALICE LHC experiment. This structure which is unusually wide in the longitudinal direction remains after removal of the known correlation-inducing effects such as elliptic flow and ordinary jet correlations. It could be probably explained only if one supposes that the ridge phenomenon in relativistic A + A collisions is rooted in the initial conditions of the thermal evolution of the system. The aim of this study is to check this hypothesis by an analysis of the evolution of the energy density in the system which at very initial stage of collisions has high density tube-like fluctuations with boost-invariant longitudinally homogeneous structure within some space-rapidity region. The transverse-velocity and energy density profiles, which develop in the system when it reaches the chemical freeze-out (T = 165 MeV) for different initial configurations at τ₀ = 0.2 fm/c, are considered.

Keywords: nucleus-nucleus collisions, hydrodynamics, ridge, fluctuations.

1. Horner M. G. Low- and intermediate-p_T di-hadron distributions in Au + Au collisions at sqrt(s_NN) = 200 GeV from STAR. J. Phys. G: Nucl. Part. Phys. 34 (2007) S995. https://doi.org/10.1088/0954-3899/34/8/S142

2. Gavin S., McLerran L., Moschelli G. Long range correlations and the soft ridge in relativistic nuclear collisions. Phys. Rev. C 79 (2009) 051902(R); arXiv:0806.4718 [nucl-th]. https://doi.org/10.1103/PhysRevC.79.051902

3. Abelev B. I., Aggarwal M. M., Ahammed Z. Long range rapidity correlations and jet production in high energy nuclear collisions. Phys. Rev. C 80 (2009) 064912; arXiv:0909.0191 [nucl-ex]. https://doi.org/10.1103/PhysRevC.80.064912

4. Adare A., Afanasiev S., Aidala C. et al. Dihadron azimuthal correlations in Au + Au collisions at sqrt(s_NN) = 200 GeV. Phys. Rev. C 78 (2008) 014901; arXiv:0801.4545 [nucl-ex]. https://doi.org/10.1103/PhysRevC.78.014901

5. Wosiek B. Latest results from the PHOBOS experiment. J. Phys. G 35 (2008) 104005. https://doi.org/10.1088/0954-3899/35/10/104005

6. Armesto N., Salgado C. A., Wiedemann U. A. et al. Measuring the Collective Flow with Jets. Phys. Rev. Lett. 93 (2004) 242301; arXiv: hepph/0405301. https://doi.org/10.1103/PhysRevLett.93.242301

7. Romatschke P. Momentum Broadening in an Anisotropic Plasma. Phys. Rev. C 75 (2007) 014901; arXiv: hep-ph/0607327. https://doi.org/10.1103/PhysRevC.75.014901

8. Majumder A., Muller B., Bass S. A. Longitudinal Broadening of Quenched Jets in Turbulent Color Fields. Phys. Rev. Let. 99 (2007) 042301; arXiv: hep-ph/0611135. https://doi.org/10.1103/PhysRevLett.99.042301

9. Wong C. Y. Ridge structure in the (Δφ)-(Δη) correlation function associated with a near-side jet. Phys. Rev. C 76 (2007) 054908; arXiv: 0707.2385. https://doi.org/10.1103/PhysRevC.76.054908

10. Chiu C. B., Hwa R. C. Pedestal and Peak Structure in Jet Correlation. Phys. Rev. C 72 (2005) 034903; arXiv nucl-th/0505014. https://doi.org/10.1103/PhysRevC.72.034903

11. Voloshin S. A. Transverse radial expansion in nuclear collisions and two particle correlations. Phys. Lett. B 632 (2006) 490; arXiv: nucl-th/0312065. https://doi.org/10.1016/j.physletb.2005.11.024

12. Shuryak E. V. On the Origin of the "Ridge" phenomenon induced by Jets in Heavy Ion Collisions. Phys. Rev. C 76 (2007) 047901; arXiv: 0706.3531. https://doi.org/10.1103/PhysRevC.76.047901

13. Schenke B., Dumitru A., Nara Y. et al. QGP collective effects and jet transport. J. Phys. G: Nucl. Part. Phys. 35 (2008) 104109. https://doi.org/10.1088/0954-3899/35/10/104109

14. Dumitru A., Gelis F., McLerran L., Venugopalan R. Glasma flux tubes and the near side ridge phenomenon at RHIC. Nucl. Phys. A 810 (2008) 91. https://doi.org/10.1016/j.nuclphysa.2008.06.012

15. Kirshner R. P. The Extravagant Universe: Exploding Stars, Dark Energy and the Accelerating Cosmos (Princeton University Press, 2002) 282 p.

16. Akkelin S. V., Hama Y., Karpenko Iu., Sinyukov Yu. M. Hydro-kinetic approach to relativistic heavy ion collisions. Phys. Rev. C 78 (2008) 034906. https://doi.org/10.1103/PhysRevC.78.034906

17. Sinyukov Yu. M., Karpenko Iu. A., Nazarenko A. V. Spacetime scales and initial conditions in relativistic A + A collisions. J. Phys. G: Nucl. Part. Phys. 35 (2008) 104071. https://doi.org/10.1088/0954-3899/35/10/104071

18. Sinyukov Yu. M., Akkelin S. V., Hama Y. Freeze-Out Problem in Hydrokinetic Approach to A + A Collisions. Phys. Rev. Lett. 89 (2002) 052301. https://doi.org/10.1103/PhysRevLett.89.052301