11,881 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
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
Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach
Certain spin Hamiltonians that give rise to tunnel splittings that are viewed
in terms of interfering instanton trajectories, are restudied using a discrete
WKB method, that is more elementary, and also yields wavefunctions and
preexponential factors for the splittings. A novel turning point inside the
classically forbidden region is analysed, and a general formula is obtained for
the splittings. The result is appled to the \Fe8 system. A previous result for
the oscillation of the ground state splitting with external magnetic field is
extended to higher levels.Comment: RevTex, one ps figur
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
Solvent Extraction & Spectrophotometric Determination of Ru(III), Rh(III) & Pd(II) using 1-(2' -Pyridylazo)-2-phenanthrol
367-36
Universal features of Thermopower in High Tc systems and Quantum Criticality
In high Tc superconductors a wide ranging connection between the doping
dependence of the transition temperature Tc and the room temperature
thermopower Q has been observed. A "universal correlation" between these two
quantities exists with the thermopower vanishing at optimum doping as noted by
OCTHH (Obertelli, Cooper, Tallon, Honma and Hor). In this work we provide an
interpretation of this OCTHH universality in terms of a possible underlying
quantum critical point (QCP) at Tc. Central to our viewpoint is the recently
noted Kelvin formula relating the thermopower to the density derivative of the
entropy. Perspective on this formula is gained through a model calculation of
the various Kubo formulas in an exactly solved 1-dimensional model with various
limiting procedures of wave vector and frequency.Comment: 12 pages, 8 figure
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