Moments of $\phi$ meson spectral functions in vacuum and nuclear matter

TL;DR

This paper investigates the properties of the $$ meson spectral function in vacuum and nuclear matter, using a combined approach of chiral effective field theory and QCD sum rules, revealing medium modifications and spectral constraints.

Contribution

It introduces a novel analysis of $$ meson spectral moments in nuclear matter by integrating chiral SU(3) theory with finite-energy QCD sum rules, including recent experimental data.

Findings

Spectral density in vacuum is constrained by $e^+ e^- o K^+ K^-$ measurements.

Nuclear matter causes broadening and asymmetry in the $$ meson peak.

First two spectral moments are consistent with QCD sum rules in both environments.

Abstract

Moments of the $\phi$ meson spectral function in vacuum and in nuclear matter are analyzed, combining a model based on chiral SU(3) effective field theory (with kaonic degrees of freedom) and finite-energy QCD sum rules. For the vacuum we show that the spectral density is strongly constrained by a recent accurate measurement of the $e^+ e^- \to K^+ K^-$ cross section. In nuclear matter the $\phi$ spectrum is modified by interactions of the decay kaons with the surrounding nuclear medium, leading to a significant broadening and an asymmetric deformation of the $\phi$ meson peak. We demonstrate that both in vacuum and nuclear matter, the first two moments of the spectral function are compatible with finite-energy QCD sum rules. A brief discussion of the next-higher spectral moment involving strange four-quark condensates is also presented.