Spectral sum rule and deconfinement transition in strongly-coupled QCD

by Konrad Tywoniuk (University of Bergen)

Thursday 7 Nov 2024, 14:00 → 15:00 Europe/Warsaw

IFJ PAN

The conventional weakly-coupled description of finite-temperature plasmas lead to the appearance of quasi-particles with thermal masses. By incorporating contributions from both the (chromo)electric scale ~gT and (chromo)magnetic scale ~g^2T, we establish thermal sum rules of quark spectral function for strongly-coupled QCD that respect Fermi-Dirac statistics as required by quantum mechanics. In sharp contrast to weakly-coupled theories, whose spectral functions consist of discontinuous zero-dimensional (singularities) and one-dimensional (branch cuts) non-analytic contributions from real energy, the derived spectral function for strongly coupled quarks features continuous but non-analytic contributions from complex energy. In light of the novel sum rules, we uncover an intrinsic QCD transition between a three-mode phase at small coupling and a one-mode phase at large coupling. The thermal mass vanishes at large coupling in line with phenomenological predictions from Dyson-Schwinger equations and gauge/gravity duality. This result provides new insights into the emergence and mechanism of the QCD transition.