60 research outputs found
Effects of Neutrino Inverse Seesaw Mechanism on the Sparticle Spectrum in CMSSM and NUHM2
We study the implications of the inverse seesaw mechanism (ISS) on the
sparticle spectrum in the Constrained Minimal Supersymmetric Standard Model
(CMSSM) and Non-Universal Higgs Model (NUHM2). Employing the maximal value of
the Dirac Yukawa coupling involving the up type Higgs doublet provides a 2-3
GeV enhancement of the lightest CP-even Higgs boson mass. This effect permits
one to have lighter colored sparticles in the CMSSM and NUHM2 scenarios with
LSP neutralino, which can be tested at LHC14. We present a variety of LHC
testable benchmark points with the desired LSP neutralino dark matter relic
abundance.Comment: 18 pages, 10 figures and 2 table
Target dark matter detection rates in models with a well-tempered neutralino
In the post-LEP2 era, and in light of recent measurements of the cosmic
abundance of cold dark matter (CDM) in the universe from WMAP, many
supersymmetric models tend to predict 1. an overabundance of CDM and 2.
pessimistically low rates for direct detection of neutralino dark matter.
However, in models with a ``well-tempered neutralino'', where the neutralino
composition is adjusted to give the measured abundance of CDM, the neutralino
is typically of the mixed bino-wino or mixed bino-higgsino state. Along with
the necessary enhancement to neutralino annihilation rates, these models tend
to give elevated direct detection scattering rates compared to predictions from
SUSY models with universal soft breaking terms. We present neutralino direct
detection cross sections from a variety of models containing a well-tempered
neutralino, and find cross section asymptotes with detectable scattering rates.
These asymptotic rates provide targets that various direct CDM detection
experiments should aim for. In contrast, in models where the neutralino mass
rather than its composition is varied to give the WMAP relic density via either
resonance annihilation or co-annihilation, the neutralino remains essentially
bino-like, and direct detection rates may be below the projected reaches of all
proposed experiments.Comment: 13 pages including 1 EPS figur
Direct, Indirect and Collider Detection of Neutralino Dark Matter In SUSY Models with Non-universal Higgs Masses
In supersymmetric models with gravity-mediated SUSY breaking, universality of
soft SUSY breaking sfermion masses m_0 is motivated by the need to suppress
unwanted flavor changing processes. The same motivation, however, does not
apply to soft breaking Higgs masses, which may in general have independent
masses from matter scalars at the GUT scale. We explore phenomenological
implications of both the one-parameter and two-parameter non-universal Higgs
mass models (NUHM1 and NUHM2), and examine the parameter ranges compatible with
Omega_CDM h^2, BF(b --> s,gamma) and (g-2)_mu constraints. In contrast to the
mSUGRA model, in both NUHM1 and NUHM2 models, the dark matter A-annihilation
funnel can be reached at low values of tan(beta), while the higgsino dark
matter annihilation regions can be reached for low values of m_0. We show that
there may be observable rates for indirect and direct detection of neutralino
cold dark matter in phenomenologically aceptable ranges of parameter space. We
also examine implications of the NUHM models for the Fermilab Tevatron, the
CERN LHC and a Sqrt(s)=0.5-1 TeV e+e- linear collider. Novel possibilities
include: very light s-top_R, s-charm_R squark and slepton_L masses as well as
light charginos and neutralinos and H, A and H^+/- Higgs bosons.Comment: LaTeX, 48pages, 26 Figures. The version with high resolution Figures
is available at http://hep.pa.msu.edu/belyaev/public/projects/nuhm/nuhm.p
Examining leptogenesis with lepton flavor violation and the dark matter abundance
Within a supersymmetric (SUSY) type-I seesaw framework with flavor-blind
universal boundary conditions, we study the consequences of requiring that the
observed baryon asymmetry of the Universe be explained by either thermal or
non-thermal leptogenesis. In the former case, we find that the parameter space
is very constrained. In the bulk and stop-coannihilation regions of mSUGRA
parameter space (that are consistent with the measured dark matter abundance),
lepton flavor-violating (LFV) processes are accessible at MEG and future
experiments. However, the very high reheat temperature of the Universe needed
after inflation (of about 10^{12} GeV) leads to a severe gravitino problem,
which disfavors either thermal leptogenesis or neutralino dark matter.
Non-thermal leptogenesis in the preheating phase from SUSY flat directions
relaxes the gravitino problem by lowering the required reheat temperature. The
baryon asymmetry can then be explained while preserving neutralino dark matter,
and for the bulk or stop-coannihilation regions LFV processes should be
observed in current or future experiments.Comment: 20 pages, 5 figures, 1 tabl
Sparticle mass spectra from SU(5) SUSY GUT models with Yukawa coupling unification
Supersymmetric grand unified models based on the gauge group SU(5) often
require in addition to gauge coupling unification, the unification of b-quark
and -lepton Yukawa couplings. We examine SU(5) SUSY GUT parameter space
under the condition of Yukawa coupling unification using 2-loop MSSM
RGEs including full 1-loop threshold effects. The Yukawa-unified solutions
break down into two classes. Solutions with low tan\beta ~3-11 are
characterized by gluino mass ~1-4 TeV and squark mass ~1-5 TeV. Many of these
solutions would be beyond LHC reach, although they contain a light Higgs scalar
with mass <123 GeV and so may be excluded should the LHC Higgs hint persist.
The second class of solutions occurs at large tan\beta ~35-60, and are a subset
of unified solutions. Constraining only unification to ~5%
favors a rather light gluino with mass ~0.5-2 TeV, which should ultimately be
accessible to LHC searches. While our unified solutions can be
consistent with a picture of neutralino-only cold dark matter, invoking
additional moduli or Peccei-Quinn superfields can allow for all of our
Yukawa-unified solutions to be consistent with the measured dark matter
abundance.Comment: 19 pages, 5 figures, 1 table, PDFLate
Adiabatic compression and indirect detection of supersymmetric dark matter
Recent developments in the modelling of the dark matter distribution in our
Galaxy point out the necessity to consider some physical processes to satisfy
observational data. In particular, models with adiabatic compression, which
include the effect of the baryonic gas in the halo, increase significantly the
dark matter density in the central region of the Milky Way. On the other hand,
the non-universality in scalar and gaugino sectors of supergravity models can
also increase significantly the neutralino annihilation cross section. We show
that the combination of both effects gives rise to a gamma-ray flux arising
from the Galactic Center largely reachable by future experiments like GLAST. We
also analyse in this framework the EGRET excess data above 1 GeV, as well as
the recent data from CANGAROO and HESS. The analysis has been carried out
imposing the most recent experimental constraints, such as the lower bound on
the Higgs mass, the \bsg branching ratio, and the muon . In addition, the
recently improved upper bound on has also been taken
into account. The astrophysical (WMAP) bounds on the dark matter density have
also been imposed on the theoretical computation of the relic neutralino
density through thermal production.Comment: 32 pages, 11 figures, final version to appear in JCA
Constrained Supersymmetric Flipped SU(5) GUT Phenomenology
We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT
model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are
constrained to be universal at some input scale, , above the GUT scale,
. We analyze the parameter space of CFSU(5) assuming that the lightest
supersymmetric particle (LSP) provides the cosmological cold dark matter,
paying careful attention to the matching of parameters at the GUT scale. We
first display some specific examples of the evolutions of the SSB parameters
that exhibit some generic features. Specifically, we note that the relationship
between the masses of the lightest neutralino and the lighter stau is sensitive
to , as is the relationship between the neutralino mass and the masses
of the heavier Higgs bosons. For these reasons, prominent features in generic
planes such as coannihilation strips and rapid-annihilation
funnels are also sensitive to , as we illustrate for several cases with
tan(beta)=10 and 55. However, these features do not necessarily disappear at
large , unlike the case in the minimal conventional SU(5) GUT. Our
results are relatively insensitive to neutrino masses.Comment: 23 pages, 8 figures; (v2) added explanations and corrected typos,
version to appear in EPJ
ВЕРОЯТНОСТНОЕ ПОТОКОРАСПРЕДЕЛЕНИЕ КАК РЕАКЦИЯ НА СТОХАСТИЧНОСТЬ НАГРУЗКИ В ЭНЕРГОСИСТЕМЕ
For the analysis and control of power systems deterministic approaches that are implemented in the form of well-known methods and models of calculation of steady-state and transient modes are mostly use in current practice. With the use of these methods it is possible to obtain solutions only for fixed circuit parameters of the system scheme and assuming that active and reactive powers as well as generation in nodal points of the network remain the same. In reality the stochastic character of power consumption cause the casual fluctuations of voltages at the nodes and power flows in electric power lines of the power system. Such casual fluctuations of operation can be estimated with the use of probabilistic simulation of the power flows. In the article the results of research of the influence of depth of casual fluctuations of the load power of the system on the probability distribution of voltage at nodes as well as on the flows of active and reactive power in the lines are presented. Probabilistic modeling of flow under stochastic load change is performed for different levels of fluctuations and under loading of the mode of the system up to peak load power. Test study to quantify the effect of stochastic variability of loads on the probabilistic distribution parameters of the modes was carried out on behalf of the electrical network of the real power system. The results of the simulation of the probability flow distribution for these fluctuations of the load, represented in the form of discrete sample values of the active power obtained with the use of the analytical Monte-Carlo method, and real data measurements of their values in the network under examination were compared.В существующей практике для анализа и управления режимами энергосистем в основном используются детерминистические подходы, которые реализуются в виде известных методов и моделей расчета установившихся и переходных режимов. С помощью этих методов можно получить решения только при фиксированных параметрах схемы системы и при допущении, что задаваемые в узлах активные и реактивные мощности нагрузки и генерации сохраняются неизменными. В условиях реальной эксплуатации стохастический характер изменчивости потребления создают случайные флуктуации напряжений в узлах и перетоков мощности в линиях электрическoй сети энергосистемы. Такие случайные флуктуации режима могут быть оценены с помощью модeлирования вероятностного потокораспределения. В статье приводятся результаты исследования влияния глубины случайных флуктуаций мощности нагрузки системы на вероятности распределения напряжений в узлах и потоки активной и реактивной мощности в линиях. Моделирование вероятностного потокораспределения в условиях стохастического изменения нагрузки выполняется для разных уровней флуктуаций и при утяжелении режима системы, вплоть до пиковой мощности нагрузки. Тестовые исследования для количественной оценки влияния стохастической изменчивости нагрузки на вероятностное распределение параметров режимов проводили на примере электрической сети реальной энергосистемы. Сравнивали результаты моделирования вероятностного потокораспределения для данных флуктуаций нагрузки, представляемых в виде дискретных выборок величин активной мощности, получаемых аналитическим путем методом Монте-Карло и данных реальных замеров их значений в исследуемой сети
What if Supersymmetry Breaking Unifies beyond the GUT Scale?
We study models in which soft supersymmetry-breaking parameters of the MSSM
become universal at some unification scale, , above the GUT scale,
\mgut. We assume that the scalar masses and gaugino masses have common
values, and respectively, at . We use the
renormalization-group equations of the minimal supersymmetric SU(5) GUT to
evaluate their evolutions down to \mgut, studying their dependences on the
unknown parameters of the SU(5) superpotential. After displaying some generic
examples of the evolutions of the soft supersymmetry-breaking parameters, we
discuss the effects on physical sparticle masses in some specific examples. We
note, for example, that near-degeneracy between the lightest neutralino and the
lighter stau is progressively disfavoured as increases. This has the
consequence, as we show in planes for several different values
of , that the stau coannihilation region shrinks as
increases, and we delineate the regions of the plane
where it is absent altogether. Moreover, as increases, the focus-point
region recedes to larger values of for any fixed and
. We conclude that the regions of the plane that are
commonly favoured in phenomenological analyses tend to disappear at large
.Comment: 24 pages with 11 eps figures; references added, some figures
corrected, discussion extended and figure added; version to appear in EPJ
Neutralino dark matter in mSUGRA/CMSSM with a 125 GeV light Higgs scalar
The minimal supergravity (mSUGRA or CMSSM) model is an oft-used framework for
exhibiting the properties of neutralino (WIMP) cold dark matter (CDM). However,
the recent evidence from Atlas and CMS on a light Higgs scalar with mass
m_h\simeq 125 GeV highly constrains the superparticle mass spectrum, which in
turn constrains the neutralino annihilation mechanisms in the early universe.
We find that stau and stop co-annihilation mechanisms -- already highly
stressed by the latest Atlas/CMS results on SUSY searches -- are nearly
eliminated if indeed the light Higgs scalar has mass m_h\simeq 125 GeV.
Furthermore, neutralino annihilation via the A-resonance is essentially ruled
out in mSUGRA so that it is exceedingly difficult to generate
thermally-produced neutralino-only dark matter at the measured abundance. The
remaining possibility lies in the focus-point region which now moves out to
m_0\sim 10-20 TeV range due to the required large trilinear soft SUSY breaking
term A_0. The remaining HB/FP region is more fine-tuned than before owing to
the typically large top squark masses. We present updated direct and indirect
detection rates for neutralino dark matter, and show that ton scale noble
liquid detectors will either discover mixed higgsino CDM or essentially rule
out thermally-produced neutralino-only CDM in the mSUGRA model.Comment: 17 pages including 9 .eps figure
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