86 research outputs found
Consistency of the dynamical high-scale type-I seesaw mechanism
We analyze the consistency of electroweak breaking within the simplest
high-scale Standard Model type-I seesaw mechanism. We derive the full two-loop
RGEs of the relevant parameters, including the quartic Higgs self-coupling of
the Standard Model. For the simplest case of bare "right-handed" neutrino mass
terms we find that, with large Yukawa couplings, the Higgs quartic
self-coupling becomes negative much below the seesaw scale, so that the model
may be inconsistent even as an effective theory. We show, however, that the
"dynamical" type-I high-scale seesaw with spontaneous lepton number violation
has better stability properties.Comment: 29 pages, 10 figures, 1 table, Published versio
ALP-portal majorana dark matter
Axion like particles(ALPs) and right handed neutrinos~(RHNs) are two
well-motivated dark matter(DM) candidates. However, these two particles have a
completely different origin. Axion was proposed to solve the Strong CP problem,
whereas RHNs were introduced to explain light neutrino masses through seesaw
mechanisms. We study the case of ALP portal RHN DM taking into account existing
constraints on ALPs. We consider the leading effective operators mediating
interactions between the ALP and SM particles and three RHNs to generate light
neutrino masses through type-I seesaw. Further, ALP-RHN neutrino coupling is
introduced to generalize the model which is restricted by the relic density and
indirect detection constraint.Comment: 18 pages, 6 figures, Matched with the published versio
Testing electroweak scale seesaw models at and colliders
We investigate the possibilities of probing the electroweak scale seesaw
scenarios such as type-I, type-II and type-III seesaw at and
colliders. For the case of type-I seesaw, the heavy neutrinos
can be produced at colliders in association with a boson. We
study a variety of final states in this case including single and multilepton
modes in association with jets to estimate bounds on the light-heavy neutrino
mixing angle. In case of type-II seesaw, doubly charged multiplets of the
SU triplet scalar can be produced in pair at collider.
We study the multi-leptonic decay modes coming from this pair production of
doubly charged Higgs and show how one can probe neutrino mass hierarchy. We
also study same sign boson production from the doubly charged Higgs to
study multilepton modes in association with missing energy. From the type-III
seesaw, we study same sign dilepton+jets and trilepton+jets modes at
collider which are coming from the neutral and charged component of
the triplet fermion in association with a boson and boson,
respectively. Due to the existing limits on the triplet fermions from the LHC
we choose heavier mass so that the gauge boson originated from the decay of a
neutral multiplet can be sufficiently boosted producing a fat-jet signature in
association with same sign dilepton and trilepton. Finally we estimate bounds
on the light neutrino-heavy triplet fermion mixing angle and compare with the
existing bounds.Comment: 53 pages, 30 figure
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