Heavy Quark Potential in QGP: DNN meets LQCD

2021 
Bottomonium states are key probes for experimental studies of the quark-gluon plasma (QGP) created in high-energy nuclear collisions. Theoretical models of bottomonium productions in high-energy nuclear collisions rely on the in-medium interactions between the bottom and antibottom quarks. The latter can be characterized by the temperature ($T$) dependent potential, with real ($V_R(T,r)$) and imaginary ($V_I(T,r)$) parts, as a function of the spatial separation ($r$). Recently, the masses and thermal widths of up to $3S$ and $2P$ bottomonium states in QGP were calculated using lattice quantum chromodynamics (LQCD). Starting from these LQCD results and through a novel application of deep neural network (DNN), here, we obtain model-independent results for $V_R(T,r)$ and $V_I(T,r)$. The temperature dependence of $V_R(T,r)$ was found to be very mild between $T\approx0-330$ MeV. For $T=150-330$ MeV, $V_I(T,r)$ shows rapid increase with $T$ and $r$, which is much larger than the perturbation theory based expectations. These findings are qualitatively different from the weak-coupling-based expectations.
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