Speaker: Paulo F. Bedaque (University of Maryland)

Title:
Restless Pions: Orbifold Boundary Conditions and Noise Suppression in Lattice QCD 

Abstract:
The study of one or more baryons in lattice QCD is severely hindered 
by the exponential decay in time of the signal-to-noise ratio. The 
rate at which the signal-to-noise decreases is a function of the the 
pion mass. More precisely, it depends on the minimum allowed pion 
energy in the box, which, for periodic boundary conditions, is equal 
to its mass. We propose a set of boundary conditions, given by a 
"parity orbifold'' construction, which eliminates the zero momentum 
pion modes, raising the minimum pion energy without altering the 
QCD ground state, and thereby improving the signal-to-noise ratio of
(multi)-baryon correlation functions at long Euclidean times. We 
discuss variations of these "restless pions" boundary conditions and 
focus on their impact on the study of nuclear forces.