Nucleon Charges from 2+1+1-flavor HISQ and 2+1-flavor clover lattices
2017 February 27
2017 March 24
Precise estimates of the nucleon charges gA, gS and gT are needed in many phenomenological analyses of SM and BSM physics. In this talk, we present results from two sets of calculations using clover valence fermions carried out on 9 ensembles of 2+1+1-flavor HISQ lattices and 4 ensembles of 2+1-flavor clover lattices. We show that high statistics can be obtained cost-effectively using the truncated solver method with bias correction and the coherent source sequential propagator technique. By performing simulations at 4–5 values of the source-sink separation t_sep, we demonstrate control over excited-state contamination using 2- and 3-state fits. Using the high-precision 2+1+1-flavor data, we perform a simultaneous fit in a, M_\pi and M_\pi L to obtain our final results for the charges.