TY - GEN

T1 - Reweighting twisted boundary conditions

AU - Bussone, Andrea

AU - Della Morte, Michele

AU - Hansen, Martin Rasmus Lundquist

AU - Pica, Claudio

PY - 2015

Y1 - 2015

N2 - Imposing twisted boundary conditions on the fermionic fields is a procedure extensively used when evaluating, for example, form factors on the lattice. Twisting is usually performed for one flavour and only in the valence, and this causes a breaking of unitarity. In this work we explore the possibility of restoring unitarity through the reweighting method. We first study some properties of the approach at tree level and then we stochastically evaluate ratios of fermionic determinants for different boundary conditions in order to include them in the gauge averages, avoiding in this way the expensive generation of new configurations for each choice of the twisting angle, θ. As expected the effect of reweighting is negligible in the case of large volumes but it is important when the volumes are small and the twisting angles are large. In particular we find a measurable effect for the plaquette and the pION correlation function in the case of θ = π/2 in a volume 16 X 8
3, and we observe a systematic upward shift in the pION dispersion relation.

AB - Imposing twisted boundary conditions on the fermionic fields is a procedure extensively used when evaluating, for example, form factors on the lattice. Twisting is usually performed for one flavour and only in the valence, and this causes a breaking of unitarity. In this work we explore the possibility of restoring unitarity through the reweighting method. We first study some properties of the approach at tree level and then we stochastically evaluate ratios of fermionic determinants for different boundary conditions in order to include them in the gauge averages, avoiding in this way the expensive generation of new configurations for each choice of the twisting angle, θ. As expected the effect of reweighting is negligible in the case of large volumes but it is important when the volumes are small and the twisting angles are large. In particular we find a measurable effect for the plaquette and the pION correlation function in the case of θ = π/2 in a volume 16 X 8
3, and we observe a systematic upward shift in the pION dispersion relation.

M3 - Article in proceedings

T3 - P o S - Proceedings of Science

BT - Proceedings, 33rd International Symposium on Lattice Field Theory (Lattice 2015) : Kobe, Japan, July 14-18, 2015

T2 - 33rd International Symposium on Lattice Field Theory

Y2 - 14 July 2015 through 18 July 2015

ER -