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arXiv · 1706.07547

Solving the $\hat{q}$ puzzle with $x$ and scale dependence

Amit Kumar·Evan Bianchi·Jacob Elledge·Abhijit Majumder·Guang-You Qin·Chun Shen
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Abstract

We present here a possible resolution of the jet quenching parameter $\hat{q}$ puzzle by exploring the momentum fraction $x$ and scale $Q^2$ dependence of $\hat{q}$, in addition to temperature dependence. We explore the momentum broadening of the jet due to Glauber gluon exchange with the quark-gluon plasma (QGP). This has led us to define the momentum fraction $x$ for the partons in the QGP. We also show here, for the first time, possible forms of the parton distribution function (PDF) of the QGP. The QGP-PDF as input in $\hat{q}$ has been used to fit the PHENIX and CMS data simultaneously. We observe that the scale evolution of the QGP-PDF and the energy of the jet are the missing ingredients responsible for the enhancement of $\hat{q}$ at the same temperature in RHIC collisions compared to LHC collisions.

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Amit Kumar, Evan Bianchi, Jacob Elledge, Abhijit Majumder, Guang-You Qin, Chun Shen. 2017-06-23. Solving the $\hat{q}$ puzzle with $x$ and scale dependence. https://doi.org/10.1016/j.nuclphysa.2017.05.015

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