Wolfgang Bock — Page 5

arXiv1992

Fermion-Higgs model with Reduced Staggered Fermions

We introduce a lattice fermion-Higgs model with one component `reduced staggered' fermions. In order to use the fermion field as efficiently as possible we couple the two {\em staggered} flavors to the O(4) Higgs field leading to a model with only one SU(2) doublet in the scaling region. The number of fermions is doubled in a numerical investigation of the model with the hybrid Monte Carlo algorithm. We present results for the phase diagram, particle masses and renormalized couplings on lattices ranging in size from $6^3 24$ to $16^3 24$.

hep-lat↗

arXiv1992

Spontaneous symmetry breaking on the lattice generated by Yukawa interaction

We study by numerical simulation a lattice Yukawa model with naive fermions at intermediate values of the Yukawa coupling $y$ when the nearest neighbour coupling $\kp$ of the scalar field $Φ$ is very weakly ferromagnetic ($\kp \approx 0$) or even antiferromagnetic ($κ< 0$) and the nonvanishing value of $\vev$ is generated by the Yukawa interaction. The renormalized Yukawa coupling $y_R$ achieves here its maximal value and this $y$-region is thus of particular importance for lattice investigations of strong Yukawa interaction. However, here the scalar field propagators have a very complex structure caused by fermion loop corrections and by the proximity of phases with antiferromagnetic properties. We develop methods for analyzing these propagators and for extracting the physical observables. We find that going into the negative $\kp$ region, the scalar field renormalization constant becomes small and $y_R$ does not seem to exceed the unitarity bound, making the existence of a nontrivial fixed point in the investigated Yukawa model quite unlikely.

hep-lat↗