3,007 research outputs found
Probing the indefinite CP nature of the Higgs Boson through decay distributions in the process
The recently discovered scalar resonance at the LHC is now almost confirmed
to be a Higgs Boson, whose CP properties are yet to be established. At the ILC
with and without polarized beams, it may be possible to probe these properties
at high precision. In this work, we study the possibility of probing departures
from the pure CP-even case, by using the decay distributions in the process
, with mainly decaying into a
pair. We have compared the case of a minimal extension of the SM case (Model I)
with an additional pseudoscalar degree of freedom, with a more realistic case
namely the CP-violating Two-Higgs Doublet Model (Model II) that permits a more
general description of the couplings. We have considered the ILC with
\,GeV and integrated luminosity of . Our
main findings are that even in the case of small departures from the CP-even
case, the decay distributions are sensitive to the presence of a CP-odd
component in Model II, while it is difficult to probe these departures in Model
I unless the pseudoscalar component is very large. Noting that the proposed
degrees of beam polarization increases the statistics, the process demonstrates
the effective role of beam polarization in studies beyond the Standard Model.
Further, our study shows that an indefinite CP Higgs would be a sensitive
laboratory to physics beyond the SM.Comment: 14 pages using revtex, 10 figures, corresponds to version accepted
for publication in Phys. Rev. D.; compared to v1, discussion extended, figure
added, table added, section reorganize
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
Effect of Epitaxial Strain on Phase Separation in Thin Films
We examine the role of an imposed epitaxial strain e in enhancing or
depressing the spinodal instability of an alloy thin film. Since the alloy film
starts with an imposed strain, phase separation offers a mechanism to relieve
it, but only when the film is elastically inhomogeneous. With
composition-dependence of elastic modulus given by y, and that of lattice
parameter by {\eta}, our simulations using the Cahn-Hilliard model show (and
analytical results for early stages confirm) that, for (ey/{\eta}) > 0, the
imposed strain adds to the driving force for phase separation, decreases the
maximally growing wave length, and expands the coherent spinodal in the phase
diagram. Further, when (ey/{\eta}) > 0.372, it expands to even outside of
chemical spinodal. Phase separation produces islands of elastically softer
(harder) phase with (without) a favorable imposed strain. These results are in
agreement with experimental results in GeSi thin films on Si and Ge substrates,
as well as in InGaAs films on GaAs substrates.Comment: 4 pages, 3 figure
Enhanced fano resonance of organic material films deposited on arrays of asymmetric split-ring resonators (A-SRRs)
Depositing very thin organic films on the surface of arrays of asymmetric split-ring resonators (A-SRRs) produces a shift in their resonance spectra that can be utilized for sensitive analyte detection. Here we show that when poly-methyl-methacrylate (PMMA) is used as an organic probe (analyte) on top of the A-SRR array, the phase and amplitude of a characteristic molecular Fano resonance associated with a carbonyl bond changes according to the spectral positions of the trapped mode resonance of the A-SRRs and their plasmonic reflection peaks. Furthermore, we localize blocks of PMMA at different locations on the A-SRR array to determine the effectiveness of detection of very small amounts of non-uniformly distributed analyte
Top Yukawa coupling measurement with indefinite CP Higgs in
We consider the issue of the top quark Yukawa coupling measurement in a model
in dependent and general case with the inclusion of CP-violation in the
coupling. Arguably the best process to study this coupling is the associa ted
production of Higgs boson along with a pair in a machine like the
International Linear Collider (ILC). While detailed analyses of the sensitivity
of the measurement assuming a Standard Model (SM) - like coupling are available
in the context of ILC, conclude that th e coupling could be pinned down at
about 10\% level with modest luminosity, our investigations show that the
scenario could be different in case of a more general coupling. The modified
Lorentz structure resulting in a changed functional dependence of the cross
section on the couplin g, along with the difference in the cross section itself
leads to considerable deviation in the sensitivity. Our studies with an ILC of
center of mass energies of 500 GeV, 800 GeV and 1000 GeV show that moderate
CP-mixing in the Higgs sector could change the sensitivity to about 20\ %,
while it could be worsened to 75\% in cases which could accommodate more
dramatic changes in the coupling. While detailed considerations of the decay
distributions point to a need for a relook at the analysis strategy followed
for the case of SM such as for a model independent analysis of the top quark
Yukawa coupling measurement. This study strongly suggests that, a joint
analysis of the CP properties and the Yukawa coupling measurement would be the
way forward at the ILC and that caution must be excercised in the measurem ent
of the Yukawa couplings and the conclusions drawn from it.Comment: 18 pages, 7 figures, uses revte
Chiral phase transition of (2+1)-flavor QCD
We present here results on the determination of the critical temperature in
the chiral limit for (2+1)-flavor QCD. We propose two novel estimators of the
chiral critical temperature where quark mass dependence is strongly suppressed
compared to the conventional estimator using pseudo-critical temperatures. We
have used the HISQ/tree action for the numerical simulation with lattices with
three different temporal extent 6, 8, 12 and varied the aspect ratio
over the range . To approach the chiral
limit, the light quark mass has been decreased keeping the strange quark mass
fixed at its physical value. Our simulations correspond to the range of pion
masses, 55 MeV 160 MeV.Comment: Prepared for the proceedings of Quark Matter 201
Topologically Massive Non-Abelian Gauge Theories: Constraints and Deformations
We study the relationship between three non-Abelian topologically massive
gauge theories, viz. the naive non-Abelian generalization of the Abelian model,
Freedman-Townsend model and the dynamical 2-form theory, in the canonical
framework. Hamiltonian formulation of the naive non-Abelian theory is presented
first. The other two non-Abelian models are obtained by deforming the
constraints of this model. We study the role of the auxiliary vector field in
the dynamical 2-form theory in the canonical framework and show that the
dynamical 2-form theory cannot be considered as the embedded version of naive
non-Abelian model. The reducibility aspect and gauge algebra of the latter
models are also discussed.Comment: ReVTeX, 17 pp; one reference added, version published in Phys. Rev.
Further results on I-limit superior and limit inferior
In this paper we obtain (after the works of Demirci) some further properties of I-limit superior and I-limit inferior and obtain the I-analogue of Cauchy criterion of convergence of a sequence of real numbers
Spectroscopic studies on the interaction of bilirubin with symmetrical alkyl diamines
The interactions of symmetrical alkyldiamines with bilirubin-IX α have been examined in dichloromethane and dioxane solutions, by visible region difference spectroscopy and florescence methods. In dioxane solutions a clear difference is observed between the complexes of the shorter chain diamines (number of spacer methylene groups (n ≤ 4) ) and the longer chain diamines (n ≥ 6) . The variations in spectral features with diamine chain length are less pronounced in dichloromethane. The spectroscopic results are consistent with the occurrence of distinct bilirubin conformations depending upon the solvent and the geometry of the interacting receptor. Based on molecular modelling two conformations are proposed. A 'ridge-tile' model similar to that observed in crystals is favoured for binding to the longer diamines, while a 'quasi-cyclic' structure is preferred for interaction with the short chain diamines
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