316 research outputs found
Effects of Relativistic Expansion on the Late-time Supernova Light Curves
The effects of relativistic expansion on the late-time supernova light curves
are investigated analytically, and a correction term to the (quasi-)exponential
decay is obtained by expanding the observed flux in terms of (\beta), where
(\beta) is the maximum velocity of the ejecta divided by the speed of light
(c). It is shown that the Doppler effect brightens the light curve owing to the
delayed decay of radioactive nuclei as well as to the Lorentz boosting of the
photon energies. The leading correction term is quadratic in (\beta), thus
being proportional to (E_{\rm k}/(M_{\rm ej} c^2)), where (E_{\rm k}) and
(M_{\rm ej}) are the kinetic energy of explosion and the ejecta mass. It is
also shown that the correction term evolves as a quadratic function of time
since the explosion. The relativistic effect is negligibly small at early
phases, but becomes of considerable size at late phases. In particular, for
supernove having a very large energy(hypernova) or exploding in a jet-like or
whatever non-spherical geometry, (^{56})Ni is likely to be boosted to higher
velocities and then we might see an appreciable change in flux. However, the
actual size of deviation from the (quasi-)exponential decay will be uncertain,
depending on other possible effects such as ionization freeze-out and
contributions from other energy sources that power the light curve.Comment: 12 pages including 2 figures, submitted to ApJ
Higgs mass, muon g-2, and LHC prospects in gauge mediation models with vector-like matters
Recently the ATLAS and CMS collaborations presented preliminary results of
Standard Model Higgs searches and reported excesses of events for a Higgs boson
at 124-126 GeV. Such a Higgs mass can be naturally realized, simultaneously
explaining the muon g-2 anomaly, in gauge-mediated SUSY breaking models with
extra vector-like matters. Upper bounds are obtained on the gluino mass,
m_{\tilde g}\lesssim 1.2 (1.8) TeV, and on the extra vector-like quark mass,
M_{Q'} \lesssim 1.0 (1.8) GeV, in the parameter region where the Higgs boson
mass is 124-126 GeV and the muon g-2 is consistent with the experimental value
at the 1 sigma (2 sigma) level. The LHC prospects are explored in the parameter
region. It is found that some of the regions are already excluded by the LHC,
and most of the parameter space is expected to be covered at \sqrt{s} = 14 TeV.
A study on the extra vector-like quarks, especially current bounds on their
masses and prospects for future searches, is also included.Comment: 28 pages, 10 figure
Probing minimal SUSY scenarios in the light of muon and dark matter
We study supersymmetric (SUSY) models in which the muon discrepancy and
the dark matter relic abundance are simultaneously explained. The muon
discrepancy, or a 3 deviation between the experimental and theoretical
results of the muon anomalous magnetic moment, can be resolved by SUSY models,
which implies at least three SUSY multiplets have masses of
. In particular, models with the
bino, higgsino and slepton having
masses are not only capable to explain the muon discrepancy but naturally
contains the neutralino dark matter with the observed relic abundance. We study
constraints and future prospects of such models; in particular, we find that
the LHC search for events with two hadronic taus and missing transverse
momentum can probe this scenario through chargino/neutralino production. It is
shown that almost all the parameter space of the scenario can be probed at the
high-luminosity LHC, and a large part can also be tested at the XENON1T
experiment as well as at the ILC.Comment: 16 pages, 5 figures; the published versio
Reconstructing Supersymmetric Contribution to Muon Anomalous Magnetic Dipole Moment at ILC
We study the possibility to determine the supersymmetric (SUSY) contribution
to the muon anomalous magnetic dipole moment by using ILC measurements of the
properties of superparticles. Assuming that the contribution is as large as the
current discrepancy between the result of the Brookhaven E821 experiment and
the standard-model prediction, we discuss how and how accurately the SUSY
contribution can be reconstructed. We will show that, in a sample point, the
reconstruction can be performed with the accuracy of ~ 13 % with the
center-of-mass energy 500 GeV and the integrated luminosity ~ 500-1000 fb-1.Comment: 18 pages, 2 figures, 2 tables; references added, to be published in
Phys.Lett.
Higgs mass and muon anomalous magnetic moment in the U(1) extended MSSM
We study phenomenological aspects of the MSSM with extra U(1) gauge symmetry.
We find that the lightest Higgs boson mass can be increased up to 125 GeV,
without introducing a large SUSY scale or large A-terms, in the frameworks of
the CMSSM and gauge mediated SUSY breaking (GMSB) models. This scenario can
simultaneously explain the discrepancy of the muon anomalous magnetic moment
(muon g-2) at the 1 sigma level, in both of the frameworks, U(1)-extended
CMSSM/GMSB models. In the CMSSM case, the dark matter abundance can also be
explained.Comment: 19 pages, 3 figures; submitted versio
Higgs Mass and Muon Anomalous Magnetic Moment in Supersymmetric Models with Vector-Like Matters
We study the muon anomalous magnetic moment (muon g-2) and the Higgs boson
mass in a simple extension of the minimal supersymmetric (SUSY) Standard Model
with extra vector-like matters, in the frameworks of gauge mediated SUSY
breaking (GMSB) models and gravity mediation (mSUGRA) models. It is shown that
the deviation of the muon g-2 and a relatively heavy Higgs boson can be
simultaneously explained in large tan-beta region. (i) In GMSB models, the
Higgs mass can be more than 135 GeV (130 GeV) in the region where muon g-2 is
consistent with the experimental value at the 2 sigma (1 sigma) level, while
maintaining the perturbative coupling unification. (ii) In the case of mSUGRA
models with universal soft masses, the Higgs mass can be as large as about 130
GeV when muon g-2 is consistent with the experimental value at the 2 sigma
level. In both cases, the Higgs mass can be above 140 GeV if the g-2 constraint
is not imposed.Comment: 26 pages; 7 figures; corrected typos; minor change
Muon g-2 vs LHC in Supersymmetric Models
There is more than 3 sigma deviation between the experimental and theoretical
results of the muon g-2. This suggests that some of the SUSY particles have a
mass of order 100 GeV. We study searches for those particles at the LHC with
particular attention to the muon g-2. In particular, the recent results on the
searches for the non-colored SUSY particles are investigated in the parameter
region where the muon g-2 is explained. The analysis is independent of details
of the SUSY models. Future prospects of the collider searches are also
discussed.Comment: 18 pages, 1 figur
- …