79 research outputs found
Gravitational waves from the first order electroweak phase transition in the symmetric singlet scalar model
Among various scenarios of baryon asymmetry of the Universe, electroweak
baryogenesis is directly connected with physics of the Higgs sector. We discuss
spectra of gravitational waves which are originated by the strongly first order
phase transition at the electroweak symmetry breaking, which is required for a
successful scenario of electroweak baryogenesis. In the symmetric singlet
scalar model, the significant gravitational waves are caused by the multi-step
phase transition. We show that the model can be tested by measuring the
characteristic spectra of the gravitational waves at future interferometers
such as LISA and DECIGO.Comment: 5 pages, 9 figures, contribution to the proceedings of Joint
Conference of ICGAC-XIII and IK15, Korea, 3--7 July 2017, based on
arXiv:1706.09721 [hep-ph
Higgs inflation in a radiative seesaw model
We investigate a simple model to explain inflation, neutrino masses and dark
matter simultaneously. This is based on the so-called radiative seesaw model
proposed by Ma in order to explain neutrino masses and dark matter by
introducing a -odd isospin doublet scalar field and -odd right-handed
neutrinos. We study the possibility that the Higgs boson as well as neutral
components of the -odd scalar doublet field can satisfy conditions from
slow-roll inflation and vacuum stability up to the inflation scale. We find
that a part of parameter regions where these scalar fields can play a role of
an inflaton is compatible with the current data from neutrino experiments and
those of the dark matter abundance as well as the direct search results. A
phenomenological consequence of this scenario results in a specific mass
spectrum of scalar bosons, which can be tested at the LHC, the International
Linear Collider and the Compact Linear Collider.Comment: 18 pages, 3 figure
Loop Suppression of Dirac Neutrino Mass in the Neutrinophilic Two Higgs Doublet Model
We extend the scalar sector of the neutrinophilic two Higgs doublet model,
where small masses of Dirac neutrinos are obtained via a small vacuum
expectation value v_nu of the neutrinophilic SU(2)_L-doublet scalar field which
has a Yukawa interaction with only right-handed neutrinos. A global U(1)_X
symmetry is used for the neutrinophilic nature of the second SU(2)_L-doublet
scalar field and also for eliminating Majorana mass terms of neutrinos. By
virtue of an appropriate assignment of the U(1)_X-charges to new particles, our
model has an unbroken Z_2 symmetry, under which the lightest Z_2-odd scalar
boson can be a dark matter candidate. In our model, v_nu is generated by the
one-loop diagram to which Z_2-odd particles contribute. We briefly discuss a
possible signature of our model at the LHC.Comment: 15 pages, 2 figures, published in Physics Letters
Strong First Order EWPT and Strong Gravitational Waves in -symmetric Singlet Scalar Extension
The nature of electroweak (EW) phase transition (PT) is of great importance.
It may give a clue to the origin of baryon asymmetry if EWPT is strong first
order. Although it is second order within the standard model (SM), a great many
extensions of the SM are capable of altering the nature. Thus, gravitational
wave (GW), which is supposed to be relics of strong first order PT, is a good
complementary probe to new physics beyond SM (BSM). We in this paper elaborate
the patterns of strong first order EWPT in the next to simplest extension to
the SM Higgs sector, by introducing a -symmetric singlet scalar. We find
that, in the -symmetric limit, the tree level barrier could lead to strong
first order EWPT either via three or two-step PT. Moreover, they could produce
two sources of GW, despite of the undetectability from the first-step strong
first order PT for the near future GW experiments. But the other source with
significant supercooling which then gives rise to
almost can be wholly covered by future space-based GW interferometers such as
eLISA, DECIGO and BBO.Comment: references adde
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