388 research outputs found
Electroweak Precision Constraints on the Littlest Higgs Model with T Parity
We compute the leading corrections to the properties of W and Z bosons
induced at the one-loop level in the SU(5)/SO(5) Littlest Higgs model with T
parity, and perform a global fit to precision electroweak data to determine the
constraints on the model parameters. We find that a large part of the model
parameter space is consistent with data. Values of the symmetry breaking scale
as low as 500 GeV are allowed, indicating that no significant fine tuning in
the Higgs potential is required. We identify a region within the allowed
parameter space in which the lightest T-odd particle, the partner of the
hypercharge gauge boson, has the correct relic abundance to play the role of
dark matter. In addition, we find that a consistent fit to data can be obtained
for large values of the Higgs mass, up to 800 GeV, due to the possibility of a
partial cancellation between the contributions to the T parameter from Higgs
loops and new physics.Comment: 23 pages, 9 figures. Minor correction
The flavor-changing bottom-strange quark production in the littlest Higgs model with T parity at the ILC
In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the
special flavor structures and some new flavor-changing (FC) couplings which
could greatly enhance the production rates of the FC processes. We in this
paper study some bottom and anti-strange production processes in the LHT model
at the International Linear Collider (ILC), i.e.,
and . The results show that the production
rates of these processes are sizeable for the favorable values of the
parameters. Therefore, it is quite possible to test the LHT model or make some
constrains on the relevant parameters of the LHT through the detection of these
processes at the ILC.Comment: 12 pages, 8 figure
Epidemiological analysis of typhoid fever in Kelantan from a retrieved registry
Aim: Despite the endemicity of typhoid in Kelantan, epidemiological data showing typhoid association to age, sex,ethnicity and district of patients is limited. This retrospective study investigated the statistical association of thesevariables from a retrieved registry.Methodology and results: Cross-tabulation using SPSS was used to analyze 1394 cases of confirmed typhoid patientsadmitted to various hospitals in Kelantan state over a six-year period. Fourteen age groups with a five-year rangeinterval were generated. There was a significant association between typhoid infection and sex of subjects, wherebyfemales were generally more susceptible than males. Ethnicity and district of typhoid patients did not show significantassociation.Conclusion, significance and impact of study: The observation of an increased number of typhoid cases with a malepredominance in the age group 5-14 and female predominance in the 20-60 age group calls for improved hygiene,continued public health education, together with better laboratory diagnostics to identify carriers, are some measures tocontrol this disease
Pair production of the heavy leptons in future high energy linear e^{+}e^{-} colliders
The littlest Higgs model with T-parity predicts the existence of the T-odd
particles, which can only be produced in pair. We consider pair production of
the T-odd leptons in future high energy linear collider ().
Our numerical results show that, as long as the T-odd leptons are not too
heavy, they can be copiously produced and their possible signals might be
detected via the processes in future
experiments.Comment: Discussions added, typos and references correcte
Extension of the sum rule for the transition rates between multiplets to the multiphoton case
The sum rule for the transition rates between the components of two
multiplets, known for the one-photon transitions, is extended to the
multiphoton transitions in hydrogen and hydrogen-like ions. As an example the
transitions 3p-2p, 4p-3p and 4d-3d are considered. The numerical results are
compared with previous calculations.Comment: 10 pages, 4 table
Lepton flavor violation decays in the topcolor-assisted technicolor model and the littlest Higgs model with parity
The new particles predicted by the topcolor-assisted technicolor ()
model and the littlest Higgs model with T-parity (called model) can
induce the lepton flavor violation () couplings at tree level or one loop
level, which might generate large contributions to some processes. Taking
into account the constraints of the experimental data on the relevant free
parameters, we calculate the branching ratios of the decay processes
with = , and
in the context of these two kinds of new physics models. We find
that the model and the model can indeed produce significant
contributions to some of these decay processes.Comment: 24 pages, 7 figure
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
A Phenomenological Analysis of Gluon Mass Effects in Inclusive Radiative Decays of the and $\Upsilon
The shapes of the inclusive photon spectra in the processes \Jp \to \gamma
X and \Up \to \gamma X have been analysed using all available experimental
data.
Relativistic, higher order QCD and gluon mass corrections were taken into
account in the fitted functions. Only on including the gluon mass corrections,
were consistent and acceptable fits obtained. Values of
GeV and GeV were found for the
effective gluon masses (corresponding to Born level diagrams) for the \Jp and
\Up respectively. The width ratios \Gamma(V \to {\rm hadrons})/\Gamma(V \to
\gamma+ {\rm hadrons}) V=\Jp, \Up were used to determine and . Values consistent with the current world
average were obtained only when gluon mass correction factors,
calculated using the fitted values of the effective gluon mass, were applied. A
gluon mass GeV, as suggested with these results, is consistent with
previous analytical theoretical calculations and independent phenomenological
estimates, as well as with a recent, more accurate, lattice calculation of the
gluon propagator in the infra-red region.Comment: 50 pages, 11 figures, 15 table
New Physics Contribution to Neutral Trilinear Gauge Boson Couplings
We study the one loop new physics effects to the CP even triple neutral gauge
boson vertices , ,
and in the context of Little Higgs models. We compute the
contribution of the additional fermions in Littles Higgs model in the framework
of direct product groups where gauge symmetry is
embedded in SU(5) global symmetry and also in the framework of simple group
where gauge symmetry breaks down to . We
calculate the contribution of the fermions to these couplings when parity
is invoked. In addition, we re-examine the MSSM contribution at the chosen
point of SPS1a' and compare with the SM and Little Higgs models.Comment: 19 pages, 5 figures, 3 table
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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