Anisotropic flow: A case for bottomonia

Abstract

Studies of J/ψ v 2 at RHIC and LHC energies have provided important elements towards the understanding on the production mechanisms and on the thermalization of charm quarks. Bottomonia has an advantage since it is a cleaner probe. A brief discussion has been provided for Υ(1S) v 2 , which can become the new probe for QGP, including the necessity of studies for small systems.

Future physics opportunities for high-density QCD at the LHC with heavy-ion and proton beams

“…Coming back to the matter of regeneration, much can be learnt about it by a measurement of the elliptic flow of Υ(1S) mesons [482], unmeasured to date in any collision system. A parallel can be drawn with that of J/ψ, which is still not properly described by models.…”

Anisotropic escape mechanism and elliptic flow of bottomonia

“…In this paper, we provide a quantitative prediction for bottomonium elliptic flow v 2 generated by the anisotropic escape mechanism; for a qualitative discussion, see Ref. [29]. In Sec.…”

Perspectives in small systems: Heavy quarks and HBT radii

“…Experimental results in small colliding systems showing emanation of QGP-like phenomena has generated avid interest in recent times, including critical discussions based on their measurements on heavy quark suppression and collective behavior. In high-energy A+A collisions, bottomonium suppression [79,80,81,82,83] can be attributed as a "golden probe" for QGP creation, since CNM effects are expected to be small in Upsilon (Υ) production [46]. Due to the larger mass of the bottomonium states compared to the charmonium ones, the measurement of bottomonia production in proton-nucleus collisions [84,85,86] allows a study of CNM effects in a different kinematic regime, and therefore complementing the J/Ψ studies [59,87,88,89].…”

“…On the other hand, it also means that the escape mechanism which underlies the anisotropic flow of bottomonia may become largely ineffective, in par-ticular for the Υ(1S). Accordingly, the measurement of a sizable flow for Υ(1S) in small systems would probably hint at the importance of initial-state correlations [46].…”

“…The bound states of heavy-quark-antiquark pairs (quarkonia) and heavy quarks which are produced via initial hard scattering processes are crucial probes for QGP [38,39,40,41,42]. Heavy quarks can access the initial anisotropy [43,44,45] of the medium produced through high energy nucleus-nucleus collisions which can be realised in the final measurement of quarkonium yield [46,47] in the experiments [48,49,50,51,52,53,54]. The modification of the yield of the different quarkonium states is sensitive to the temperature of the QGP [41,55,56].…”