3 research outputs found
Degenerate BESS Model: The possibility of a low energy strong electroweak sector
We discuss possible symmetries of effective theories describing spinless and
spin 1 bosons, mainly to concentrate on an intriguing phenomenological
possibility: that of a hardly noticeable strong electroweak sector at
relatively low energies. Specifically, a model with both vector and axial
vector strong interacting bosons may possess a discrete symmetry imposing
degeneracy of the two sets of bosons (degenerate BESS model). In such a case
its effects at low energies become almost invisible and the model easily passes
all low energy precision tests. The reason lies essentially in the fact that
the model automatically satisfies decoupling, contrary to models with only
vectors. For large mass of the degenerate spin one bosons the model becomes
identical at the classical level to the standard model taken in the limit of
infinite Higgs mass. For these reasons we have thought it worthwhile to fully
develop the model, together with its possible generalizations, and to study the
expected phenomenology. For instance, just because of its invisibility at low
energy, it is conceivable that degenerate BESS has low mass spin one states and
gives quite visible signals at existing or forthcoming accelerators.Comment: 37 pages, LaTeX, 14 figures (uuencoded
Scale of fermion mass generation
Unitarity of longitudinal weak vector boson scattering implies an upper bound
on the scale of electroweak symmetry breaking, 1 TeV. Appelquist and Chanowitz have derived an analogous
upper bound on the scale of fermion mass generation, proportional to ,
by considering the scattering of same-helicity fermions into pairs of
longitudinal weak vector bosons in a theory without a standard Higgs boson. We
show that there is no upper bound, beyond that on the scale of electroweak
symmetry breaking, in such a theory. This result is obtained by considering the
same process, but with a large number of longitudinal weak vector bosons in the
final state. We further argue that there is no scale of (Dirac) fermion mass
generation in the standard model. In contrast, there is an upper bound on the
scale of Majorana-neutrino mass generation, given by . In general, the upper bound on the scale of fermion mass generation
depends on the dimensionality of the interaction responsible for generating the
fermion mass. We explore the scale of fermion mass generation in a variety of
excursions from the standard model: models with fermions in nonstandard
representations, a theory with higher-dimension interactions, a
two-Higgs-doublet model, and models without a Higgs boson.Comment: 31 pages, 9 figures; version accepted for publication in Phys. Rev.
Deriving the mass of particles from Extended Theories of Gravity in LHC era
We derive a geometrical approach to produce the mass of particles that could
be suitably tested at LHC. Starting from a 5D unification scheme, we show that
all the known interactions could be suitably deduced as an induced symmetry
breaking of the non-unitary GL(4)-group of diffeomorphisms. The deformations
inducing such a breaking act as vector bosons that, depending on the
gravitational mass states, can assume the role of interaction bosons like
gluons, electroweak bosons or photon. The further gravitational degrees of
freedom, emerging from the reduction mechanism in 4D, eliminate the hierarchy
problem since generate a cut-off comparable with electroweak one at TeV scales.
In this "economic" scheme, gravity should induce the other interactions in a
non-perturbative way.Comment: 30 pages, 1 figur