Hadron Electric Dipole Moments from CP-Odd Operators of Dimension Five Via QCD Sum Rules: The Vector Meson

TL;DR

This paper analyzes the electric dipole moment of the rho-meson caused by CP-violating operators of dimension 4 and 5 using QCD sum rules, highlighting the roles of quark EDMs and chromoelectric dipole moments.

Contribution

It provides a comprehensive calculation of the rho-meson EDM from CP-odd operators, including effects of Peccei-Quinn symmetry, using QCD sum rules.

Findings

Quark EDMs produce smaller rho-meson EDMs consistent with quark models.

Chromoelectric dipole moments contribute significantly, sometimes more than EDMs.

Peccei-Quinn symmetry affects the hadronic EDM via axion potential contributions.

Abstract

We present a complete analysis of the electric dipole moment (EDM) of the \rho-meson induced by CP violating operators of dimension 4 and 5 within the QCD sum rules approach. The set of CP-odd operators includes the theta term and the electric and chromoelectric dipole moments of the three light quarks. We find that the \rho-meson EDM induced purely by the EDMs of quarks is smaller, but still in reasonable agreement, with the predictions of a naive constituent quark model. However, the chromoelectric dipole moments, including that of the strange quark, give comparable and sometimes larger contributions. We also consider the effect on the hadronic EDM of the existence of Peccei-Quinn symmetry. When this symmetry is active, chromoelectric dipole moments induce a linear term in the axion potential which leads to a numerically important vacuum contribution to the hadronic EDM.