Sensitivity of jet quenching to enhancement of the medium opacity near TC

Abstract

[Introduction] One of the main goals of the study of high transverse momentum ( P T ) observables in the context of ultrarelativistic heavy-ion collisions is the determination of properties of QCD matter. In particular, the transport coefficients ˆ q and ˆ e characterizing the interaction of the medium with a high p T parton are accessible via hard probes. However, a precision extraction of their temperature dependence from current data faces the problem that neither the space-time geometry of the evolving matter nor the link between thermodynamics and transport coefficients is unambiguously known. Thus, various conjectured scenarios exist for how thermodynamics and transport coefficients behave close to the phase transition. While often a behavior with the energy density ˆ q ∼ 3 / 4 is assumed, leading to a decrease of the scaled ˆ q ( T ) /T 3 close to the critical temperature T C , other scenarios expect instead a near T C enhancement of jet quenching. In this work, the response of both the extraction of ˆ q and the enhancement of v 2 at high P T to modification of jet quenching close to T C is investigated within Y a JEM ,a well-tested in-medium shower evolution Monte Carlo code, embedded into a fluid dynamics simulation for the medium, thus allowing a gauge of the magnitude of the effect in a realistic framework.