# Poster presented by Wolfgang Bock

**Poster Session**
**Topic:** Chiral Gauge Theories

**Authors:** W. Bock, M.F.L. Golterman, K.C. Leung, Y. Shamir (presented by W. Bock)

### Lattice transcriptions of the continuum Lorentz gauge-fixing action

**Abstract:** We examine the naive lattice transcription of the continuum Lorentz gauge-fixing action. The trouble with this gauge-fixing action is that it supports a dense set of lattice Gribov copies for the identity field $U_{mu x}=I$, each being a classical vacuum of the action. Since perturbation theory is not applicable in this case, we use non-perturbative methods (mean-field approximation and numerical simulation) to study the model. We extend the parameter space to connect this model with another model in which a unique ground state, namely for $U_{mu x}=I$i, exists, and perturbartion theory can be used. The phase diagram of this extended model is determined, and the universality class of the naive-transcription lattice model is discussed.

Massimo Campostrini,
`campo@mailbox.difi.unipi.it`