High transverse momentum quarkonium production and dissociation in heavy ion collisions

Abstract

We calculate the yields of quarkonia in heavy ion collisions at RHIC and the LHC as a function of their transverse momentum. Based upon non-relativistic quantum chromodynamics, our results include both color-singlet and color-octet contributions and feed-down effects from excited states. In reactions with ultra-relativistic nuclei, we focus on the consistent implementation of dynamically calculated nuclear matter effects, such as coherent power corrections, cold nuclear matter energy loss, and the Cronin effect in the initial state. In the final state, we consider radiative energy loss for the color-octet state and collisional dissociation of quarkonia as they traverse through the QGP. Theoretical results are presented for J/ψ and Υ and compared to experimental data where applicable. At RHIC, a good description of the high-pT J/ψ modification observed in central Cu+Cu and Au+Au collisions can be achieved within the model uncertainties. We find that measurements of J/ψ yields in proton-nucleus reactions are needed to constrain the magnitude of cold nuclear matter effects. At the LHC, a good description of the experimental data can be achieved only in mid-central and peripheral Pb+Pb collisions. The large five-fold suppression of prompt J/ψ in the most central nuclear reactions may indicate for the first time possible thermal effects at the level of the quarkonium wavefunction at large transverse momenta.

Production of non-photonic electrons in U+U collisions at √sNN= 193 GeV at the STAR experiment

“…The nuclear modification factor of NPE Figure 4: Left: Nuclear modification factor of NPE versus p T in U+U collisions compared to AuAu collisions and model [19], [20], [21]. Right: Nuclear modification factor of NPE in U+U and Au+Au collisions, D mesons in U+U and Au+Au collisions [4] and π ± in Au+Au collisions [22] versus number of participants.…”

“…R AA of NPE in U+U collisions is compared to theoretical model including CNM effects (Cronin effect and initial state energy loss), QGP effects such as jet quenching, and new attenuation mechanism for open heavy flavor mesons, called collisional dissociation, originating from short formation times of D and B mesons. The dashed green line represents the case with lower initial state energy loss but large Cronin effect and the dot-dashed magenta line the case with higher initial state energy loss and small Cronin effect [19], [20], [21]. In addition, nuclear modification factor of NPE as a function of number of participants is plotted in Fig.…”

The fate of the weakly-bound ψ(2s) in nuclear matter

“…Several models that include various combinations of gluon shadowing, charm energy loss, multiple scattering in the nucleus, and nuclear break-up have been able to reproduce facets of the J/ψ data [8,9,10]. As a further constraint, we turn to the excited charmonium state ψ(2s).…”

Quarkonia at finite temperature in relativistic heavy-ion collisions

“…So the in-medium behavior of the precursor to J/ψ needs to be understood [56,57]. In particular, for large p T J/ψ the precursor is mostly in color octet state, and it has been argued that it interacts much more readily with the medium, leading to dissolution [42,56] or quenching of p T [57]. The interaction of the J/ψ (and other quarkonia, which may decay into J/ψ) with the medium is probably the most studied part of the scheme outlined above.…”