Color Screening and Quark-Quark Interactions in Finite Temperature QCD

TL;DR

This paper investigates how static diquark sources are screened in finite temperature QCD, revealing that at high temperatures, quark-quark interactions follow Casimir scaling and suggesting possible heavy quark bound states above the deconfinement temperature.

Contribution

It provides a detailed analysis of diquark screening in 2-flavor QCD and explores the potential existence of heavy quark-quark bound states at high temperatures.

Findings

Diquark screening at short distances resembles single quark screening.

At large distances, two quarks are screened independently.

Support for $bb$ bound states up to about $2T_c$, but not for $cc$ states.

Abstract

We analyze the screening of static diquark sources in 2-flavor QCD and compare results with the screening of static quark-antiquark pairs. We show that a two quark system in a fixed color representations is screened at short distances like a single quark source in the same color representation whereas at large distances the two quarks are screened independently. At high temperatures we observe that the relative strength of the interaction in diquark and quark-antiquark systems, respectively, obeys Casimir scaling. We use this result to examine the possible existence of heavy quark-quark bound states in the high temperature phase of QCD. We find support for the existence of $bb$ states up to about $2T_c$ while $cc$ states are unlikely to be formed above $T_c$.