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Christoph Frick

Publications and source records attributed to Christoph Frick.

5 recordsLinked to original sources
arXiv1994

Dynamical fermion mass generation by strong gauge interaction shielded by a scalar field

The strongly coupled lattice gauge models with confined fermion and scalar matter fields, which in a certain phase break dynamically a global chiral symmetry, are reconsidered from the point of view of the existence of heavy fermions. If these models are interpreted as describing a new strong force beyond the standard model, such heavy fermions can arise as neutral bound states of the fundamental fermion and scalar. The discussed mechanism could be considered as an alternative to the Higgs mechanism.

hep-lat↗
arXiv1992

Can the Couplings in the Fermion-Higgs Sector of the Standard Model be Strong?

We present results for the renormalized quartic self-coupling $λ_R$ and the Yukawa coupling $y_R$ in a lattice fermion-Higgs model with two SU(2)$_L$ doublets, mostly for large values of the bare couplings. One-component (`reduced') staggered fermions are used in a numerical simulation with the Hybrid Monte Carlo algorithm. The fermion and Higgs masses and the renormalized scalar field expectation value are computed on $L^3 24$ lattices, where $L$ ranges from $6$ to $16$. In the scaling region these quantities are found to have a $1/L^2$ dependence, which is used to determine their values in the infinite volume limit. We then calculate the $y_R$ and $λ_R$ from their tree level definitions in terms of the masses and renormalized scalar field expectation value, extrapolated to infinite volume. The scalar field propagators can be described for momenta up to the cut-off by one fermion loop renormalized perturbation theory and the results for $λ_R$ and $y_R$ come out to be close to the tree level unitarity bounds. There are no signs that are in contradiction with the triviality of the Yukawa and quartic self-coupling.

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↗