Speaker
Description
Title: Light scalars from triplet Higgs fields: neutrinos, cosmology,
and colliders
Content:
SU(2) triplet Higgs fields coupling to leptons are a means to generate
Majorana masses for neutrinos. A priori the neutral scalar and
pseudoscalar components S and A could be light, as e.g. realised in
majoron models in which A is the Goldstone boson of spontaneously broken
lepton number. Such a light particle mediating a new force between
neutrinos can alleviate cosmological puzzles such as the
scalar-to-tensor ratio in the cosmic microwave background and the
different values of the Hubble constant observed at different
cosmological scales. While all renormalisable triplet models do not
permit to have either A or S light with the other neutral particle heavy
enough to forbid $Z\to AS$ as required by LEP data, I show that one can
circumvent this roadblock with dimension-6 terms in the Higgs
potential. If A or S are light, the singly (doubly) charged triplet
Higgs boson is lighter than 280 GeV (400 GeV), which make the model
falsifiable with better LHC data.
