Electric Dipole Moment Results from lattice QCD

TL;DR

This paper employs the gradient flow technique to compute nucleon electric dipole moments induced by QCD $ heta$-term and Weinberg operator using lattice QCD, providing a new approach to handle operator renormalization.

Contribution

It introduces the use of gradient flow to define and calculate electric dipole moments in lattice QCD, simplifying renormalization of local operators.

Findings

Electric dipole moments calculated for different pion masses.

Gradient flow effectively simplifies operator renormalization.

Results provide insights into CP violation in QCD.

Abstract

We utilize the gradient flow to define and calculate electric dipole moments induced by the strong QCD $\theta$-term and the dimension-6 Weinberg operator. The gradient flow is a promising tool to simplify the renormalization pattern of local operators. The results of the nucleon electric dipole moments are calculated on PACS-CS gauge fields (available from the ILDG) using $N_{f}=2+1$, of discrete size $32^{3}\times 64$ and spacing $a \simeq 0.09$ fm. These gauge fields use a renormalization-group improved gauge action and a non-perturbatively $O(a)$ improved clover quark action at $\beta = 1.90$, with $c_{SW} = 1.715$. The calculation is performed at pion masses of $m_{\pi} \simeq 411,701$ MeV.