6533b830fe1ef96bd1297a8b
RESEARCH PRODUCT
On the effect of excited states in lattice calculations of the nucleon axial charge
Harvey B. MeyerMaxwell T. Hansensubject
PhysicsNuclear and High Energy PhysicsRoper resonanceChiral perturbation theory010308 nuclear & particles physicsHigh Energy Physics::LatticeHigh Energy Physics - Lattice (hep-lat)Nuclear TheoryFOS: Physical sciencesLattice QCD01 natural sciencesAmplitudeHigh Energy Physics - LatticeLattice (order)Excited stateQuantum mechanicsQuantum electrodynamics0103 physical scienceslcsh:QC770-798lcsh:Nuclear and particle physics. Atomic energy. Radioactivity010306 general physicsNucleonLattice model (physics)description
Excited-state contamination is one of the dominant uncertainties in lattice calculations of the nucleon axial-charge, $g_A$. Recently published results in leading-order chiral perturbation theory (ChPT) predict the excited-state contamination to be independent of the nucleon interpolator and positive. However, empirical results from numerical lattice calculations show negative contamination (downward curvature), indicating that present-day calculations are not in the regime where the leading-order ChPT predictions apply. In this paper we show that, under plausible assumptions, one can reproduce the behavior of lattice correlators by taking into account final-state $N \pi$ interactions, in particular the effect of the Roper resonance, and by postulating a sign change in the infinite-volume $N \to N \pi$ axial-vector transition amplitude.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2017-10-01 |