420 research outputs found
Peccei-Quinn Relaxion
The relaxation mechanism, which solves the electroweak hierarchy problem
without relying on TeV scale new physics, crucially depends on how a
Higgs-dependent back-reaction potential is generated. In this paper, we suggest
a new scenario in which the scalar potential induced by the QCD anomaly is
responsible both for the relaxation mechanism and the Peccei-Quinn mechanism to
solve the strong CP problem. The key idea is to introduce the relaxion and the
QCD axion whose cosmic evolutions become quite different depending on an
inflaton-dependent scalar potential. Our scheme raises the cutoff scale of the
Higgs mass up to 10^7 GeV, and allows reheating temperature higher than the
electroweak scale as would be required for viable cosmology. In addition, the
QCD axion can account for the observed dark matter of the universe as produced
by the conventional misalignment mechanism. We also consider the possibility
that the couplings of the Standard Model depend on the inflaton and become
stronger during inflation. In this case, the relaxation can be implemented with
a sub-Planckian field excursion of the relaxion for a cutoff scale below 10
TeV.Comment: 14 pages, 1 figure; minor changes, accepted for publication in JHE
Moduli-induced Baryogenesis
We study a scenario for baryogenesis in modular cosmology and discuss its
implications for the moduli stabilization mechanism and the supersymmetry
(SUSY) breaking scale. If moduli fields dominate the Universe and decay into
the standard model particles through diatonic couplings, the right amount of
baryon asymmetry can be generated through CP violating decay of gluino into
quark and squark followed by baryon-number violating squark decay. We find
that, in the KKLT-type moduli stabilization, at least two non-perturbative
terms are required to obtain a sizable CP phase, and that the successful
baryogenesis is possible for the soft SUSY breaking mass heavier than O(1) TeV.
A part of the parameter space for successful baryogenesis can be probed at the
collider experiments, dinucleon decay search experiment, and the measurements
of electric dipole moments of neutron and electron. It is also shown that
similar baryogenesis works in the case of the gravitino- or the
saxion-dominated Universe.Comment: 36 pages, 2 figure
Higgs Mixing in the NMSSM and Light Higgsinos
We explore the effects of Higgs mixing in the general next-to-minimal
supersymmetric Standard Model (NMSSM). Extended to include a gauge singlet, the
Higgs sector can naturally explain the observed Higgs boson mass in TeV scale
supersymmetry without invoking large stop mixing. This is particularly the case
when the singlet scalar is light so that singlet-doublet mixing increases the
mass of the SM-like Higgs boson. In such a case the Higgs mixing has
interesting implications following from the fact that the higgsino mass
parameter and the singlet coupling to Higgs bilinear crucially depend on the
Higgs boson masses and mixing angles. For the mixing compatible with the
current LHC data on the Higgs signal rates, the higgsinos are required to be
relatively light, around or below a few hundred GeV, as long as the heavy
doublet Higgs boson has a mass smaller than about 250\sqrt{\tan\beta} GeV and
the singlet-like Higgs boson is consistent with the LEP constraint. In
addition, the Higgs coupling to photons can receive a sizable contribution of
either sign from the charged-higgsino loops combined with singlet-doublet
mixing.Comment: 26 pages, 5 figures, Higgs data updated, discussion extended, typos
fixed, to appear in JHE
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