3,789 research outputs found
Invisible decays of the lightest Higgs boson in supersymmetric models
We consider supersymmetric models in which the lightest Higgs scalar can
decay invisibly consistent with the constraints on the ~GeV state
discovered at the CERN LHC. We consider the invisible decay in the minimal
supersymmetric standard model~(MSSM), as well its extension containing an
additional chiral singlet superfield, the so-called next-to-minimal or
nonminimal supersymmetric standard model~(NMSSM).We consider the case of MSSM
with both universal as well as nonuniversal gaugino masses at the grand unified
scale, and find that only an grand unified model with unnaturally large
representation can give rise to sufficiently light neutralinos which can
possibly lead to the invisible decay . Following this, we consider the case of NMSSM in detail, where also
we find that it is not possible to have the invisible decay of the lightest
Higgs scalar with universal gaugino masses at the grand unified scale. We
delineate the regions of the NMSSM parameter space where it is possible to have
the lightest Higgs boson to have a mass of about GeV, and then
concentrate on the region where this Higgs can decay into light neutralinos,
with the soft gaugino masses and as two independent parameters,
unconstrained by grand unification. We also consider, simultaneously, the other
important invisible Higgs decay channel in the NMSSM, namely the decay into the
lightest CP odd scalars, , which is studied in detail. With
the invisible Higgs branching ratio being constrained by the present LHC
results, we find that ~GeV and ~GeV is disfavored in
NMSSM for fixed values of the other input parameters. The dependence of our
results on the parameters of NMSSM is discussed in detail.Comment: 20 pages, 14 figures, to appear in Physical Review
Shortcuts to Thermodynamic Computing: The Cost of Fast and Faithful Erasure
Landauer's Principle states that the energy cost of information processing
must exceed the product of the temperature and the change in Shannon entropy of
the information-bearing degrees of freedom. However, this lower bound is
achievable only for quasistatic, near-equilibrium computations -- that is, only
over infinite time. In practice, information processing takes place in finite
time, resulting in dissipation and potentially unreliable logical outcomes. For
overdamped Langevin dynamics, we show that counterdiabatic potentials can be
crafted to guide systems rapidly and accurately along desired computational
paths, providing shortcuts that allows for the precise design of finite-time
computations. Such shortcuts require additional work, beyond Landauer's bound,
that is irretrievably dissipated into the environment. We show that this
dissipated work is proportional to the computation rate as well as the square
of the information-storing system's length scale. As a paradigmatic example, we
design shortcuts to erase a bit of information metastably stored in a
double-well potential. Though dissipated work generally increases with erasure
fidelity, we show that it is possible perform perfect erasure in finite time
with finite work. We also show that the robustness of information storage
affects the energetic cost of erasure---specifically, the dissipated work
scales as the information lifetime of the bistable system. Our analysis exposes
a rich and nuanced relationship between work, speed, size of the
information-bearing degrees of freedom, storage robustness, and the difference
between initial and final informational statistics.Comment: 19 pages, 7 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/scte.ht
Isolating CP-violating \gamma ZZ coupling in e+e- \to \gamma Z with transverse beam polarizations
We revisit the process at the ILC with transverse beam
polarization in the presence of anomalous CP-violating coupling
and coupling . We point out that if
the final-state spins are resolved, then it becomes possible to fingerprint the
anomalous coupling {\rm Re}.90% confidence level limit on {\rm
Re} achievable at ILC with center-of-mass energy of 500 GeV or 800
GeV with realistic initial beam polarization and integrated luminosity is of
the order of few times of when the helicity of is used and
when the helicity of is used. The resulting corrections at
quadratic order to the cross section and its influence on these limits are also
evaluated and are shown to be small. The benefits of such polarization
programmes at the ILC are compared and contrasted for the process at hand. We
also discuss possible methods by which one can isolate events with a definite
helicity for one of the final-state particles.Comment: 13 pages, 9 figures, using RevTex; v2 is a significantly revised
version of v1, and corresponds to the version that has been published in
Physical Review
Chronic ethanol feeding alters miRNA expression dynamics during liver regeneration.
BACKGROUND: Adaptation to chronic ethanol (EtOH) treatment of rats results in a changed functional state of the liver and greatly inhibits its regenerative ability, which may contribute to the progression of alcoholic liver disease.
METHODS: In this study, we investigated the effect of chronic EtOH intake on hepatic microRNA (miRNA) expression in male Sprague-Dawley rats during the initial 24 hours of liver regeneration following 70% partial hepatectomy (PHx) using miRNA microarrays. miRNA expression during adaptation to EtOH was investigated using RT-qPCR. Nuclear factor kappa B (NFκB) binding at target miRNA promoters was investigated with chromatin immunoprecipitation.
RESULTS: Unsupervised clustering of miRNA expression profiles suggested that miRNA expression was more affected by chronic EtOH feeding than by the acute challenge of liver regeneration after PHx. Several miRNAs that were significantly altered by chronic EtOH feeding, including miR-34a, miR-103, miR-107, and miR-122 have been reported to play a role in regulating hepatic metabolism and the onset of these miRNA changes occurred gradually during the time course of EtOH feeding. Chronic EtOH feeding also altered the dynamic miRNA profile during liver regeneration. Promoter analysis predicted a role for NFκB in the immediate-early miRNA response to PHx. NFκB binding at target miRNA promoters in the chronic EtOH-fed group was significantly altered and these changes directly correlated with the observed expression dynamics of the target miRNA.
CONCLUSIONS: Chronic EtOH consumption alters the hepatic miRNA expression profile such that the response of the metabolism-associated miRNAs occurs during long-term adaptation to EtOH rather than as an acute transient response to EtOH metabolism. Additionally, the dynamic miRNA program during liver regeneration in response to PHx is altered in the chronically EtOH-fed liver and these differences reflect, in part, differences in miRNA expression between the EtOH-adapted and control livers at the baseline state prior to PHx
Effect of Time-Delay on a Ratio-Dependent Food Chain Model
This paper aims to study the effect of time-delay on a tritrophic food chainmodel with Michaelis-Menten type ratio-dependent functional responses. Boundednessof the time-delayed system is established. A simple criterion for deterministic extinctionis derived. It has been shown that the time-delay may introduce instability in the systemthrough Hopf bifurcation. Computer simulations are carried out to explain the analyticalfindings. It is discussed how these ideas illuminate some of the observed properties ofreal populations in the field, and explores practical implications
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