Detecting flavor content of the vacuum using the Dirac operator spectrum

We compute the overlap Dirac spectrum on three ensembles generated using 2+1 flavor domain wall fermions. The spectral density is determined up to $lambdasim$100 MeV with sub-percentage statistical uncertainty. The three ensembles have different lattice spacings and two of them have quark masses tuned to the physical point. We show that we can resolve the flavor content of the sea quarks and constrain their masses using the Dirac spectral density. We find that the density is close to a constant below $lambdale$ 20 MeV (but 10% higher than that in the 2-flavor chiral limit) as predicted by chiral perturbative theory ($chi$PT), and then increases linearly due to the strange quark mass. Using the next to leading order $chi$PT, one can extract the light and strange quark masses with $sim$20% uncertainties. Using the non-perturbative RI/MOM renormalization, we obtain the chiral condensates at $overline{textrm{MS}}$ 2 GeV as $Sigma=(260.3(0.7)(1.3)(0.7)(0.8) textrm{MeV})^3$ in the $N_f=2$ (keeping the strange quark mass at the physical point) chiral limit and $Sigma_0=(232.6(0.9)(1.2)(0.7)(0.8) textrm{MeV})^3$ in the $N_f=3$ chiral limit, where the four uncertainties come from the statistical fluctuation, renormalization constant, continuum extrapolation and lattice spacing determination. Note that {$Sigma/Sigma_0=1.40(2)(2)$ is much larger than 1} due to the strange quark mass effect.

Lattice QCD package GWU-code and QUDA with HIP

The open source HIP platform for GPU computing provides an uniform framework to support both the NVIDIA and AMD GPUs, and also the possibility to porting the CUDA code to the HIP- compatible one. We present the porting progress on the Overlap fermion inverter (GWU-code) and also the general Lattice QCD inverter package - QUDA. The manual of using QUDA on HIP and also the tips of porting general CUDA code into the HIP framework are also provided.

Proton Mass Decomposition from the QCD Energy Momentum Tensor

We report results on the proton mass decomposition and also on related quark and glue momentum fractions. The results are based on overlap valence fermions on four ensembles of $N_f = 2+1$ DWF configurations with three lattice spacings and three volumes, and several pion masses including the physical pion mass. With fully non-perturbative renormalization (and universal normalization on both quark and gluon), we find that the quark energy and glue field energy contribute 33(4)(4)% and 37(5)(4)% respectively in the $overline{MS}$ scheme at $mu = 2$ GeV. A quarter of the trace anomaly gives a 23(1)(1)% contribution to the proton mass based on the sum rule, given 9(2)(1)% contribution from the $u, d,$ and $s$ quark scalar condensates. The $u,d,s$ and glue momentum fractions in the $overline{MS}$ scheme are in good agreement with global analyses at $mu = 2$ GeV.