5 research outputs found
The lightest Higgs mass in supersymmetric models with extra dimensions
In the four-dimensional supersymmetric standard model extended with gauge
singlets the lightest Higgs boson mass, , has an important contribution
proportional to the squared of the superpotential coupling of
singlets to Higgs fields, . The requirement of
perturbativity up to the unification scale yields an upper bound on GeV. In extensions to theories with (longitudinal) extra dimensions at the
TeV where such coupling exists and massive Kaluza-Klein states fall into N=2
representations, if either of the Higgs or singlet fields live in the bulk of
the extra dimensions, the -function of is suppressed due to
the absence of anomalous dimension of hypermultiplets to leading order. This
implies a slower running of and an enhancement of its low energy
value. The upper bound increases to values GeV.Comment: Latex2e, 11 pages, 1 figur
Charge Asymmetry in the Brane World and Formation of Charged Black Holes
In theories with an infinite extra dimension, free particles localized on the
brane can leak out to the extra space. We argue that if there were color
confinement in the bulk, electrons would be more able to escape than quarks and
than protons (which are composed states). Thus, this process generates an
electric charge asymmetry on brane matter densities. A primordial charge
asymmetry during Big Bang Nucleosynthesis era is predicted. We use current
bounds on this and on electron disappearance to constrain the parameter space
of these models. Although the generated asymmetry is generically small, it
could be particularly enhanced on large densities as in astrophysical objects,
like massive stars. We suggest the possibility that such accumulation of charge
may be linked, upon supernova collapse, to the formation of a charged Black
Hole and the generation of Gamma-Ray Bursts.Comment: Four pages, one figure. Minor changes, conclusions remai
TeV scale unification in four dimensions versus extra dimensions
The gauge coupling constant unification at the low ((TeV)) scale can be
obtained just in four dimensions, without help of the power like
renormalization group evolution in extra dimensions, due to the presence of
some extra particle states at intermediate scales. We show explicit examples of
such extra states in the range of 100 GeV -- 1 TeV which can be easily observed
on future colliders and can have important impact on the particle
phenomenology. The problems of the low scale grand unification and proton
stability are also discussed.Comment: 12 pages, Latex, 2 figure