Toward a Direct Measurement of Partial Restoration of Chiral Symmetry at J-PARC E16 via Density-induced Chiral Mixing

TL;DR

This paper proposes a method to detect partial restoration of chiral symmetry in nuclear matter by observing the degeneracy of specific mesons in J-PARC E16 experiments, using an effective Lagrangian and transport simulations.

Contribution

It introduces a novel approach combining effective Lagrangian modeling and transport simulations to measure chiral symmetry restoration via meson degeneracy in nuclear collisions.

Findings

Potential 2.5 sigma signal detection with current experimental setup.

Effective Lagrangian approach captures charge-conjugation symmetry breaking.

Simulation results suggest observable meson mixing signals.

Abstract

The degeneracy of chiral partners is an ideal signal for measuring the restoration of the spontaneously broken chiral symmetry in QCD. In this work, we investigate the observability of the $\phi$ - $f_1(1420)$ degeneracy in the J-PARC E16 experiment, which measures di-electrons emitted from 30 GeV pA collisions. We for this purpose make use of an effective Lagrangian approach, which naturally incorporates the broken charge-conjugation symmetry in nuclear matter and the ensuing anomaly-induced mixing between vector and axial-vector mesons, to compute the spectral function relevant for the experimental measurement. The real-time dynamics of the pA collision is obtained from a transport simulation. Including experimental background and resolution effects on top of that, we find that a signal of the $\phi$ - $f_1(1420)$ mixing can be observed around 2.5 $\sigma$ with the Run2 statistics planned for the J-PARC E16 experiment with an ideal mixing strength.