One Loop Corrections to the Rho Parameter in Higgsless Models

Abstract

A large class of deconstructed Higgsless model is known to satisfy the tree-level experimental bounds on the electroweak precision parameters. In particular, an approximate custodial symmetry insures that the tree-level $\rho$ parameter is exactly one, for arbitrary values of the model parameters, and regardless of fermion delocalization. In this note we expand on previous work by considering the fermionic one-loop contributions to $\rho$, which are essentially due to loops with top and bottom modes. We analyze the dependence on the number $N$ of internal SU(2) sites in models with a ``flat background''. We find that the new-physics contribution rapidly increases with $N$, to quickly stabilize for large values of $N$. Experimental upper bounds on $\rho$ translate into lower bounds on the mass of the heavy fermions. These, however, are weakly correlated to $N$, and the three-site model (N=1) turns out to be already an excellent approximation for the continuum model ($N\to \infty$).

20 pages, 5 figures

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Cited by in corpus (3)

• Heavy Vectors in Higgs-less models
• Does the three site Higgsless model survive the electroweak precision tests at loop?
• From hidden symmetry to extra dimensions: a five dimensional formulation of the Degenerate BESS model