Chiral Partners and their Electromagnetic Radiation -- Ingredients for a systematic in-medium calculation

TL;DR

This paper discusses the nature of chiral partners of hadrons as hadronic molecules, emphasizing the importance of in-medium effects and vector-meson dominance for systematic calculations of their properties in nuclear matter.

Contribution

It introduces a systematic, self-consistent framework for in-medium calculations of hadronic spectra, highlighting the role of vector-meson dominance and hadronic molecules.

Findings

Chiral partners are hadronic molecules, not quark-based states.

Deconfinement leads to degeneracy of chiral partner spectra in medium.

Vector-meson dominance is crucial for in-medium hadronic calculations.

Abstract

It is argued that the chiral partners of the lowest-lying hadrons are hadronic molecules and not three-quark or quark-antiquark states, respectively. As an example the case of a_1 as the chiral partner of the rho is discussed. Deconfinement -- or as a precursor large in-medium widths for hadronic states -- is proposed as a natural way to accommodate for the fact that at chiral restoration the respective in-medium spectra of chiral partners must become degenerate. Ingredients for a systematic and self-consistent in-medium calculation are presented with special emphasis on vector-meson dominance which emerges from a recently proposed systematic counting scheme for the mesonic sector including pseudoscalar and vector mesons as active degrees of freedom.