# Lattice QCD with $N_f = 2+1+1 $ domain-wall quarks

## TL;DR

This paper reports on a lattice QCD simulation with 2+1+1 flavors using domain-wall fermions, calculating hadron spectra that agree well with experimental data and predicting unobserved charmed baryons.

## Contribution

First detailed lattice QCD simulation with optimal domain-wall fermions for 2+1+1 flavors, providing accurate hadron spectra and predictions for charmed baryons.

## Key findings

- Mass spectra agree with experimental values
- Predicted masses of unobserved charmed baryons
- Simulation achieved near-physical quark masses

## Abstract

We perform hybrid Monte Carlo simulation of (2+1+1)-flavors lattice QCD with the optimal domain-wall fermion (which has the effective 4D Dirac operator exactly equal to the Zolotarev optimal rational approximation of the overlap Dirac operator). The gauge ensemble is generated on the $32^3 \times 64 $ lattice with the extent $ N_s = 16 $ in the fifth dimension, and with the plaquette gauge action at $ \beta = 6/g^2 = 6.20 $. The lattice spacing ($ a \simeq 0.063 $ fm) is determined by the Wilson flow, using the value $ \sqrt{t_0} = 0.1416(8) $ fm obtained by the MILC Collaboration for the $(2+1+1)$-flavors QCD. The masses of $s$ and $c$ quarks are fixed by the masses of the vector mesons $ \phi(1020) $ and $ J/\psi(3097) $ respectively; while the mass of the $u/d$ quarks is heavier than their physical values, with the unitary pion mass $ M_\pi \simeq 280$ MeV (and $ M_\pi L \simeq 3 $). We compute the point-to-point quark propagators, and measure the time-correlation functions of meson and baryon interpolators. Our results of the mass spectra of the lowest-lying hadrons containing $ s $ and $ c $ quarks are in good agreement with the high energy experimental values, together with the predictions of the charmed baryons which have not been observed in experiments.