2025/03/10 by Park, Sungwoo, Gupta, Rajan, Bhattacharya, Tanmoy +4 · 3 citations
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat)
paper · doi:10.48550/arxiv.2503.07100
We present lattice results for the flavor diagonal charges of the proton from the analysis of eight ensembles generated using 2+1+1-flavors of highly improved staggered quarks (HISQ) by the MILC collaboration. The calculation includes all the needed connected and disconnected contributions to nucleon three-point function. For extracting matrix elements using fits to the spectral decomposition of these correlation functions, two strategies to remove excited state contributions are employed and compared. To renormalize these charges, the 2+1-flavor mixing matrix is calculated in the RI-sMOM intermediate scheme on the lattice. The final results are presented in the MS scheme at scale 2GeV. The axial charges for the proton are gAu = 0.781(25), gAd = -0.440(39), and gAs = -0.055(9); the tensor charges are gTu = 0.782(28), gTd = -0.195(16), and gTs = -0.0016(12); and the scalar charges are gSu = 9.39(88), gSd = 8.84(93), and gSs = 0.37(14). Results for the neutron are given by the u ↔ d interchange. Results for the sigma terms are σπN|\rm standard = 42(6)~\rm MeV from a "standard" analysis and σπN|N π = 61(6)~\rm MeV from a "Nπ" analysis that includes the contributions of multihadron Nπ excited states as motivated by chiral perturbation theory. Our preferred value σπN|N π is consistent with the phenomenological extraction from π- N scattering data. The strangeness content of the proton, for which the "standard" analysis is appropriate, is σs|\rm standard = 35(13)~\rm MeV.