Lattice QCD Calculation of Nuclear Parity Violation

Abstract

We present the first lattice QCD calculation of the leading-order momentum-independent parity violating coupling between pions and nucleons, $h_{\pi NN}^1$. The calculation performs measurements on dynamical anisotropic clover gauge configurations, with a spatial extent of $L\sim 2.5$ fm, a spatial lattice spacing of $a_s\sim 0.123$ fm, and a pion mass of $m_{\pi }\sim 389$ MeV. While this first calculation does not include non-perturbative renormalization of the bare parity-violating operators, a chiral extrapolation to the physical pion mass, or contributions from disconnected (quark-loop) diagrams, these are expected to result in systematic errors within the quoted statistical error. We find a contribution from the `connected' diagrams of $h_{\pi NN}^{1,con}=(1.099\pm 0.505_{-0.064}^{+0.058})\times 10^{-7}$, consistent with current experimental bounds and previous model-dependent theoretical predictions.

Comments: 5 pg., 3 fig