20 research outputs found
Natural Islands for a 125 GeV Higgs in the scale-invariant NMSSM
We study whether a 125 GeV standard model-like Higgs boson can be
accommodated within the scale-invariant NMSSM in a way that is natural in all
respects, i.e., not only is the stop mass and hence its loop contribution to
Higgs mass of natural size, but we do not allow significant tuning of NMSSM
parameters as well. We pursue as much as possible an analytic approach which
gives clear insights on various ways to accommodate such a Higgs mass, while
conducting complementary numerical analyses. We consider both scenarios with
singlet-like state being heavier and lighter than SM-like Higgs. With A-terms
being small, we find for the NMSSM to be perturbative up to GUT scale, it is
not possible to get 125 GeV Higgs mass, which is true even if we tune
parameters of NMSSM. If we allow some of the couplings to become
non-perturbative below the GUT scale, then the non-tuned option implies that
the singlet self-coupling, kappa, is larger than the singlet-Higgs coupling,
lambda, which itself is order 1. This leads to a Landau pole for these
couplings close to the weak scale, in particular below ~10^4 TeV. In both the
perturbative and non-perturbative NMSSM, allowing large A_lambda, A_kappa gives
"more room" to accommodate a 125 GeV Higgs, but a tuning of these A-terms may
be needed. In our analysis we also conduct a careful study of the constraints
on the parameter space from requiring global stability of the desired vacuum
fitting a 125 GeV Higgs, which is complementary to existing literature. In
particular, as the singlet-Higgs coupling lambda increases, vacuum stability
becomes more serious of an issue.Comment: 34 pages, 4 figures, references added, minor corrections to text and
figures, version to be published in JHE
Nanoporous ultra-high specific surface inorganic fibres
Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have been fabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidal silica nanoparticles, followed by selective removal of the PVA component. The configurations of the composite and inorganic nanofibres were investigated by changing the average silica particle diameters and the concentrations of colloidal silica particles in polymer solutions. After the removal of PVA by calcination, the fibre shape of pure silica particle assembly was maintained. The nanoporous silica fibres were assembled as a porous membrane with a high surface roughness. From the results of Brunauer-Emmett-Teller (BET) measurements, the BET surface area of inorganic silica nanofibrous membranes was increased with the decrease of the particle diameters. The membrane composed of silica particles with diameters of 15 nm showed the largest BET surface area of 270.3 m(2) g(-1) and total pore volume of 0.66 cm(3) g(-1). The physical absorption of methylene blue dye molecules by nanoporous silica membranes was examined using UV-vis spectrometry. Additionally, the porous silica membranes modified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures
TeV scale mirage mediation in NMSSM
We study the next-to-minimal supersymmetric standard model. We consider soft
supersymmetry breaking parameters, which are induced by the mirage mediation
mechanism of supersymmetry breaking. We concentrate on the mirage mediation,
where the so-called mirage scale is the TeV scale. In this scenario, we can
realize the up-type Higgs soft mass of O(200) GeV, while other masses such as
gaugino masses and stop masses are heavy such as 1 TeV or more. Cancellation
between the effective \mu-term and the down-type Higgs soft mass ameliorates
the fine-tuning in the electroweak symmetry breaking even for \mu=O(500) GeV.
The mixing between the doublet and singlet Higgs bosons is suppressed by
(\lambda/\kappa)/tan\beta. Then the lightest doublet Higgs mass naturally
reaches 125 GeV lifted by the new quartic coupling. The higgsino and singlino
are light and their linear combination is the lightest superparticle.Comment: 24 pages, 24 figures, Numerical analysis is replaced with the version
calculated by NMSSMTools. Comments and references are added on the suppressed
doublet-singlet mixing and cases in which the 125 GeV boson is the 2nd
lightest CP-even scalar. The version accepted by JHE
Higgs Portal to Visible Supersymmetry Breaking
We propose a supersymmetric extension of the standard model whose Higgs
sector induces a spontaneous supersymmetry breaking by itself. Unlike the
minimal extension, the current Higgs mass bound can be evaded even at the
tree-level without the help of the soft breaking terms due to the usual hidden
sector, as is reminiscent of the next to minimal case. We also have a possibly
light pseudo-goldstino in our visible sector in addition to extra Higgs
particles, both of which stem from supersymmetry breaking dynamics. In such a
setup of visible supersymmetry breaking, we may see a part of supersymmetry
breaking dynamics rather directly in future experiments.Comment: 23 pages, 6 figures, references adde
Higgs Boson Mass in Low Scale Gauge Mediation Models
We consider low scale gauge mediation models with a very light gravitino
m_{3/2}~16 eV, in the light of recent experimental hints on the Higgs boson
mass. The light gravitino is very interesting since there is no gravitino
over-production problem, but it seems difficult to explain the Higgs boson mass
of ~125 GeV. This is because of the conflict between the light gravitino mass
and heavy SUSY particle masses needed for producing the relatively heavy Higgs
boson mass. We consider two possible extensions in this paper: a singlet
extension of the Higgs sector, and strongly coupled gauge mediation. We show
that there is a large parameter space, in both scenarios, where the Higgs boson
mass of ~125 GeV is explained without any conflict with such a very light
gravitino.Comment: 23 pages, 5 figure
Peccei-Quinn NMSSM in the light of 125 GeV Higgs
We study the phenomenology of the Peccei-Quinn invariant extension of the
next-to-minimal supersymmetric standard model (NMSSM) in view of the recent
discovery of a 125 GeV Higgs boson. The minimal model having no quadratic and
cubic terms of the NMSSM singlet field predicts a light singlino-like lightest
supersymmetric particle (LSP). The model is strongly constrained by the Higgs
invisible decay and the dark matter characteristic of the LSP, while some
constraints can be relaxed by assuming that the saxion, the CP-even companion
of the axion in the Peccei-Quinn sector, causes a late-time entropy production
diluting the thermal LSP density. The collider signal of the model contains
multi-jet and plus missing energy, which can be discovered in the early
stage of the 14 TeV LHC running.Comment: 40 pages, 10 figures, 6 tables. v3: references added, several
statements added and corrected, comments on the small tadpole soft term added
in sec. 2.
Enhanced Higgs associated production with a top quark pair in the NMSSM with light singlets
Precision measurements of the 125 GeV Higgs resonance recently discovered at
the LHC have determined that its properties are similar to the ones of the
Standard Model (SM) Higgs boson. However, the current uncertainties in the
determination of the Higgs boson couplings leave room for significant
deviations from the SM expectations. In fact, if one assumes no correlation
between the top-quark and gluon couplings to the Higgs, the current global fit
to the Higgs data lead to central values of the Higgs couplings to the
bottom-quark and the top-quark that are about 2 away from the SM
predictions. In a previous work, we showed that such a scenario could be
realized in the Next to Minimal Supersymmetric extension of the SM (NMSSM), for
heavy singlets and light MSSM-like Higgs bosons and scalar top quarks, but for
couplings that ruined the perturbative consistency of the theory up to the GUT
scale. In this work we show that a perturbative consistent scenario, for
somewhat heavier stops, may be obtained in the presence of light singlets. An
interesting bonus of this scenario is the possibility of explaining an excess
of events observed in CP-even Higgs searches at LEP2.Comment: 17 pages; v2: discussion on unphysical global minima and new
benchmark table added; matches published versio