by Debasish Das. Published: 13 November 2017

On the occasion of the recent publication of a review of QCD, quark gluon plasma, heavy quark hybrids, and heavy quark state production in pp and A-A collisions, ALICE Matters shares a short summary of this topic by one of the authors.

Among the possible probes of the Quark-Gluon Plasma (QGP), the interest in heavy quarks is motivated by their unique role in the diagnostics of the highly excited medium created in relativistic heavy ion collisions. The properties of heavy quarkonium states (which are bound states of heavy quark-antiquark pairs) in a hot and dense Quantum Chromodynamics (QCD) medium have been intensely studied for over two decades both experimentally and theoretically. Heavy quark mass is large and so heavy quark production is believed to be occurred largely within the earliest phase of the collision. Therefore, the measurement of quarkonia is expected to provide essential information on the properties of the strongly-interacting system formed in the early stages of heavy ion collisions.

A recent review [1] summarizes the Quantum Chromodynamics Cosmological Phase Transitions, the QGP, the production of heavy quark states via proton-proton (pp) and heavy ion collisions (A-A) at relativistic energies using the mixed hybrid theory for the Psi (2S) and Upsilon (3S) states; it also covers the possible detection of the QGP via heavy quark production using A-A collisions. The recent research on fragmentation for the production of D mesons is reviewed as well, along with the future theoretical and experimental research on the Collins and Sivers fragmentation functions for pions produced in polarized p-p collisions.

Studies of Ψ(Psi) and Υ(Upsilon) production cross sections in pp collisions with E =√s=13 TeV to E = 5 and E =14 TeV used the mixed heavy quark hybrid theory in which the Ψ(2S) and Υ(3S) are 50 % hybrid states [1,2]. The hybrid component has active gluons, which enhances the production of Ψ(2S) and Υ(3S) compared to the standard model. A recent study of experiments at    √ s = 7 TeV were used to test the mixed heavy hybrid theory [3].

The suppression of Ψ(2S) and Υ(3S) production in p-Pb (p-A) collisions were explored at 8 TeV [4]. With Ψ(2S) and Υ(3S) being 50 % hybrid states, the suppression is enhanced as these mesons traverse the Pb nucleus [4]. This study is a prediction for both ALICE and LHCb experiments. Finally, analyzing the differential rapidity cross-sections for J/Ψ, Ψ(2S), Υ(1S), Υ(2S) and Y(3S) in Pb-Pb (A-A) collisions [5] at the top LHC energies (5.02 TeV), the Ψ(2S) and Υ(3S) hybrid states were compared with standard model to bring out their importance in the search of QGP.

 

For more details:

[1] Leonard S. Kisslinger and Debasish Das, International Journal of Modern Physics A, Vol. 31, 1630010 (2016) ; DOI: 10.1142/S0217751X16300106

[2] Leonard S. Kisslinger, Phys. Rev. D Vol. 79, 114026 (2009);

[3] Leonard S. Kisslinger and Debasish Das, International Journal of Theoretical Physics, Volume 55, p 4362(2016); DOI: 10.1007/s10773-016-3059-y

[4] Leonard S. Kisslinger and Debasish Das, International Journal of Theoretical Physics, Volume 55, p 5152(2016); DOI: 10.1007/s10773-016-3136-2

[5] Leonard S. Kisslinger and Debasish Das, Journal of High Energy Physics, 1709 (2017) 105.