Pion spectral properties above the chiral crossover of QCD

Journal of High Energy Physics

Regular Article - Theoretical Physics

Owe Philipsen¹  Peter Lowdon¹ 

[1] Institut für Theoretische Physik, Goethe-Universität, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany;

关键词: Finite Temperature or Finite Density;    Non-Zero Temperature and Density;    Thermal Field Theory;    Lattice QCD;   

DOI  :  10.1007/JHEP10(2022)161

 received in 2022-08-25, accepted in 2022-10-17,  发布年份 2022

来源: Springer

【 摘 要 】

Spectral functions encode a wealth of information about the dynamics of any given system, and the determination of their non-perturbative characteristics is a long-standing problem in quantum field theory. Whilst numerical simulations of lattice QCD provide ample data for various Euclidean correlation functions, the inversion required to extract spectral functions is an ill-posed problem. In this work, we pursue previously established constraints imposed by field locality at finite temperature T, namely that spectral functions possess a non-perturbative representation which generalises the well-known Källén-Lehmann spectral form to T > 0. Using this representation, we analyse lattice QCD data of the spatial pseudo-scalar correlator in the temperature range 220–960 MeV, and obtain an analytic expression for the corresponding spectral function, with parameters fixed by the data. From the structure of this spectral function we find evidence for the existence of a distinct pion state above the chiral pseudo-critical temperature Tpc, and contributions from its first excitation, which gradually melt as the temperature increases. As a non-trivial test, we find that the extracted spectral function reproduces the corresponding temporal lattice correlator data for T = 220 MeV.

【 授权许可】

Unknown   
© The Author(s) 2022