Hadronic matrix elements of proton decay on the lattice

We report on our on-going project to calculate proton decay matrix elements using domain-wall fermions on the lattice. By summarizing the history of the proton decay calculation on the lattice, we reveal the systematic errors of those calculations. Then we discuss our approach to tackle those uncertainties and show our preliminary results on the matrix elements.Comment: 4 pages, 2 figures, talk presented at CIPANP2003: Conference on the Intersections of Particle and Nuclear Physics, New York City, May 19-24, 200

Improving chiral property of domain-wall fermions by reweighting method

The reweighting method is applied to improve the chiral property of domain-wall fermions. One way to achieve this is to enlarge $L_s$, the size of fifth dimension, which controls the size of the induced chiral symmetry breaking. While this is a type of reweighting method for shifting the action parameter, it seems non-trivial since this reweighting means change of the five dimensional lattice volume. In this report, we address issues in this direction of reweighting and evaluate its effectiveness.Comment: 7 pages, talk presented at The XXVII International Symposium on Lattice Field Theory, July 26-31 2009, Peking University, Beijing, Chin

Nucleon Decay with Domain-Wall Fermions

We report on our on-going project to calculate the nucleon decay matrix elements with domain-wall fermions. Operator mixing is discussed employing a non-perturbative renormalization. Bare matrix elements of all the possible decay modes induced by the dimension-six operators are calculated with the direct method, which are compared with the indirect calculation using chiral perturbation theory.Comment: Lattice2003(matrix), 3 pages, 2 figure

Axial U(1)U(1) symmetry at high temperature in 2-flavor lattice QCD

We investigate the axial $U(1)_A$ symmetry breaking above the critical temperature in two-flavor lattice QCD. The ensembles are generated with dynamical M\"obius domain-wall or reweighted overlap fermions. The $U(1)_A$ susceptibility is extracted from the low-modes spectrum of the overlap Dirac eigenvalues. We show the quark mass and temperature dependences of $U(1)_A$ susceptibility. Our results at $T=220 \, \mathrm{MeV}$ imply that the $U(1)_A$ symmetry is restored in the chiral limit. Its coincidence with vanishing topological susceptibility is observed.Comment: 8 pages, 4 figures, Proceedings of the 35th International Symposium on Lattice Field Theory, June 18-24, 2017, Granada, Spai

Nucleon Decay Matrix Elements for Domain-Wall Fermions

We report on the nucleon decay matrix elements with domain-wall fermions in quenched approximation. Results from direct and indirect method are compared with a focus on the process of a proton decaying to a pion and a lepton. We discuss the renormalization necessary for the matching to the continuum theory. Preliminary results for the renormalized chiral lagrangian parameters are presented.Comment: Lattice2002(matrixel), 3 pages, 1 figur

Axial U(1) symmetry and Dirac spectra in high-temperature phase of Nf=2N_f=2 lattice QCD

The axial $U(1)$ symmetry in the high-temperature phase is investigated with $N_f = 2$ lattice QCD simulations. The gauge ensembles are generated with M\"obius domain-wall fermions, and the overlap/domain-wall reweighting is applied. We find that the $U(1)_A$ susceptibility evaluated from the spectrum of overlap-Dirac eigenvalues is strongly suppressed in the chiral limit. We also study its volume dependence.Comment: 7 pages, 2 figures, talk presented at the 36th International Symposium on Lattice Field Theory (Lattice 2018), 22-28 July, 2018, Michigan, US