Cherenkov and Fano effects at the origin of asymmetric vector mesons in nuclear media

TL;DR

This paper explains the asymmetry in vector meson production in nuclear media as resulting from Cherenkov and Fano effects, which alter the expected mass distribution shapes observed in experiments.

Contribution

It introduces a novel interpretation of asymmetric vector mesons in nuclear media as Cherenkov and Fano effects, supported by data analysis.

Findings

Mass distributions deviate from Breit-Wigner shape in the low-mass wing.

Parameters derived from data support Cherenkov and Fano interpretations.

Reasonable agreement with rho-meson experimental data.

Abstract

It is argued that the experimentally observed phenomenon of asymmetric vector mesons produced in nuclear media during high energy nucleus-nucleus collisions can be explained as Cherenkov and Fano effects. The mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape in the low-mass wing of the resonance. That is explained by the positive real part of the amplitude in this wing for classic Cherenkov treatment and further detalized in quantum mechanics as the interference of direct and continuum states in Fano effect. The corresponding parameters are found from the comparison with rho-meson data and admit reasonable explanation.