Abstract
As fermions are added to a lattice gauge theory, one is driven to stronger bare coupling in order to maintain the same renormalized coupling. Stronger bare couplings are usually associated with larger gauge fluctuations, leading to larger cutoff effects and more expensive simulations. In theories with many light fermions, sometimes the desired physical region cannot be reached before encountering a phase boundary. We show that these undesired effects can be reduced by adding Pauli--Villars fields. We reach significantly larger renormalized couplings while at the same time damping short-distance fluctuations of the gauge field. This may allow for controlled continuum extrapolations from large lattice spacings.
Highlights
There is wide interest in the nonperturbative properties of asymptotically free gauge theories at strong renormalized coupling
We review the idea that massive fields can be considered as generating an effective action for the gauge field
In this paper we investigated the possibility of countering the effective action generated by fermions at short distances by including heavy Pauli-Villars fields
Summary
There is wide interest in the nonperturbative properties of asymptotically free gauge theories at strong renormalized coupling. Tuning the bare coupling to zero decreases the lattice spacing and reduces cutoff effects but requires increasing the lattice volume to keep the physical volume sufficiently large Various improvement programs, both perturbative and nonperturbative, attempt to reduce lattice artifacts so that simulations even at reasonable lattice volumes can predict continuum physics with high precision. Comparing the two panels reveals that, as the number of fermions increases, reaching the same value of g2GF (if possible) is accompanied by a smaller plaquette value In other words, it comes at the price of stronger short-distance gauge field fluctuations. The effect of the PV bosons can be summarized as an addition to the lattice action They generate a local effective gauge action [6] that can balance the screening effect of the fermions at short distances.
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