72 research outputs found
Supersymmetric CP Violation in in Minimal Supergravity Model
Direct CP asymmetries and the CP violating normal polarization of lepton in
inclusive decay B \to X_s l^+ l^- are investigated in minimal supergravity
model with CP violating phases. The contributions coming from exchanging
neutral Higgs bosons are included. It is shown that the direct CP violation in
branching ratio, A_{CP}^1, is of {\cal{O}}(10^{-3}) for l=e, \mu, \tau. The CP
violating normal polarization for l=\mu can reach 0.5 percent when tan\beta is
large (say, 36). For l=\tau and in the case of large \tan\beta, the direct CP
violation in backward-forward asymmetry, A_{CP}^2, can reach one percent, the
normal polarization of \tau can be as large as a few percent, and both are
sensitive to the two CP violating phases, \phi_\mu and \phi_{A_0}, and
consequently it could be possible to observe them (in particular, the normal
polarization of \tau) in the future B factories.Comment: 14 pages, latex, 5 figure
Analysis of Various Polarization Asymmetries In The Inclusive Decay In The Fourth-Generation Standard Model
In this study a systematical analysis of various polarization asymmetries in
inclusive b \rar s \ell^+ \ell^- decay in the standard model (SM) with four
generation of quarks is carried out. We found that the various asymmetries are
sensitive to the new mixing and quark masses for both of the and
channels. Sizeable deviations from the SM values are obtained. Hence, b \rar s
\ell^+ \ell^- decay is a valuable tool for searching physics beyond the SM,
especially in the indirect searches for the fourth-generation of quarks (.Comment: 19 Pages, 10 Figures, 3 Table
The Electric Dipole Moment and CP Violation in in SUGRA Models with Nonuniversal Gaugino Masses
The constraints of electric dipole moments (EDMs) of electron and neutron on
the parameter space in supergravity (SUGRA) models with nonuniversal gaugino
masses are analyzed. It is shown that with a light sparticle spectrum, the
sufficient cancellations in the calculation of EDMs can happen for all phases
being order of one in the small tan case and all phases but
() order of one in the large tan case. This is
in contrast to the case of mSUGRA in which in the parameter space where
cancellations among various SUSY contributions to EDMs happen
must be less than for small and for
large . Direct CP asymmetries and the T-odd polarization of lepton in
are investigated in the models. In the large tan case,
and for l= () can be enhanced by about a factor of
ten (ten) and ten (three) respectively compared to those of mSUGRA.Comment: 12 pages, latex, 4 figures, a few change
Lepton Polarization and Forward-Backward Asymmetries in b -> s tau+ tau-
We study the spin polarizations of both tau leptons in the decay b -> s tau+
tau-. In addition to the polarization asymmetries involving a single tau, we
construct asymmetries for the case where both polarizations are simultaneously
measured. We also study forward-backward asymmetries with polarized tau's. We
find that a large number of asymmetries are predicted to be large, >~ 10%. This
permits the measurement of all Wilson coefficients and the b-quark mass, thus
allowing the standard model (SM) to be exhaustively tested. Furthermore, there
are many unique signals for the presence of new physics. For example,
asymmetries involving triple-product correlations are predicted to be tiny
within the SM, O(10^{-2}). Their observation would be a clear signal of new
physics.Comment: 21 pages, LaTeX, 4 figures (included). Paper somewhat reorganized,
references greatly expanded, conclusions unchange
B -> X_s gamma in Supersymmetry with Explicit CP Violation
We discuss B -> X_s gamma decay in both constrained and unconstrained
supersymmetric models with explicit CP violation within the minimal flavor
violation scheme by including tan(beta) -enhanced large contributions beyond
the leading order. In this analysis, we take into account the relevant
cosmological and collider bounds, as well as electric dipole moment
constraints. In the unconstrained model, there are portions of the parameter
space yielding a large CP asymmetry at leading order (LO). In these regions, we
find that the CP phases satisfy certain sum rules, e.g., the sum of the phases
of the \mu parameter and the stop trilinear coupling centralize around \pi with
a width determined by the experimental bounds. In addition, at large values of
tan(beta), the sign of the CP asymmetry tracks the sign of the gluino mass, and
the CP asymmetry is significantly larger than the LO prediction. In the
constrained minimal supersymmetric standard model based on minimal
supergravity, we find that the decay rate is sensitive to the phase of the
universal trilinear coupling. This sensitivity decreases at large values of the
universal gauino mass. We also show that for a given set of the mass
parameters, there exists a threshold value of the phase of the universal
trilinear coupling which grows with tan(beta) and beyond which the experimental
bounds are satisfied. In both supersymmetric scenarios, the allowed ranges of
the CP phases are wide enough to have phenomenological consequences.Comment: 25 pages, 11 figures. Added references, made minor changes in the
text; journal versio
Exploring flavor structure of supersymmetry breaking from rare B decays and unitarity triangle
We study effects of supersymmetric particles in various rare B decay
processes as well as in the unitarity triangle analysis. We consider three
different supersymmetric models, the minimal supergravity, SU(5) SUSY GUT with
right-handed neutrinos, and the minimal supersymmetric standard model with U(2)
flavor symmetry. In the SU(5) SUSY GUT with right-handed neutrinos, we consider
two cases of the mass matrix of the right-handed neutrinos. We calculate direct
and mixing-induced CP asymmetries in the b to s gamma decay and CP asymmetry in
B_d to phi K_S as well as the B_s--anti-B_s mixing amplitude for the unitarity
triangle analysis in these models. We show that large deviations are possible
for the SU(5) SUSY GUT and the U(2) model. The pattern and correlations of
deviations from the standard model will be useful to discriminate the different
SUSY models in future B experiments.Comment: revtex4, 36 pages, 10 figure
The design and implementation of a study to investigate the effectiveness of community vs hospital eye service follow-up for patients with neovascular age-related macular degeneration with quiescent disease
IntroductionStandard treatment for neovascular age-related macular degeneration (nAMD) is intravitreal injections of anti-VEGF drugs. Following multiple injections, nAMD lesions often become quiescent but there is a high risk of reactivation, and regular review by hospital ophthalmologists is the norm. The present trial examines the feasibility of community optometrists making lesion reactivation decisions.MethodsThe Effectiveness of Community vs Hospital Eye Service (ECHoES) trial is a virtual trial; lesion reactivation decisions were made about vignettes that comprised clinical data, colour fundus photographs, and optical coherence tomograms displayed on a web-based platform. Participants were either hospital ophthalmologists or community optometrists. All participants were provided with webinar training on the disease, its management, and assessment of the retinal imaging outputs. In a balanced design, 96 participants each assessed 42 vignettes; a total of 288 vignettes were assessed seven times by each professional group.The primary outcome is a participant's judgement of lesion reactivation compared with a reference standard. Secondary outcomes are the frequency of sight threatening errors; judgements about specific lesion components; participant-rated confidence in their decisions about the primary outcome; cost effectiveness of follow-up by optometrists rather than ophthalmologists.DiscussionThis trial addresses an important question for the NHS, namely whether, with appropriate training, community optometrists can make retreatment decisions for patients with nAMD to the same standard as hospital ophthalmologists. The trial employed a novel approach as participation was entirely through a web-based application; the trial required very few resources compared with those that would have been needed for a conventional randomised controlled clinical trial
Present Status of Inclusive Rare B Decays
We give a status report on inclusive rare B decays, highlighting recent
developments and open problems. We focus on the decay modes , and and on their
role in the search for new physics. Most of the inclusive rare B decays are
important modes of flavour physics due to the small hadronic uncertainties.
They can be regarded as laboratories to search for new physics. We collect the
experimental data already available from CLEO and the factories BABAR and
BELLE. We review the NLL and NNLL QCD calculations of the inclusive decay rates
that were recently completed, and discuss future prospects, especially the
issue of the charm mass scheme ambiguity. Finally, we analyse the
phenomenological impact of these decay modes, in particular on the CKM
phenomenology and on the indirect search for supersymmetry. We also briefly
discuss direct CP violation in inclusive rare B decays, as well as the rare
kaon decays and , which
offer complementary theoretically clean information.Comment: 80 pages, 37 figures, latex, references added Invited contribution to
Reviews of Modern Physic
Overconfidence in Labor Markets
This chapter reviews how worker overconfidence affects labor markets. Evidence from psychology and economics shows that in many situations, most people tend to overestimate their absolute skills, overplace themselves relative to others, and overestimate the precision of their knowledge. The chapter starts by reviewing evidence for overconfidence and for how
overconfidence affects economic choices. Next, it reviews economic explanations for overconfidence. After that, it discusses research on the impact of worker overconfidence on labor markets where wages are determined by bargaining between workers and firms. Here, three key questions are addressed. First, how does worker overconfidence affect effort provision
for a fixed compensation scheme? Second, how should firms design compensation schemes when workers are overconfident? In particular, will a compensation scheme offered to an overconfident worker have higher-or lower-powered incentives than that offered to a worker with accurate self-perception? Third, can worker overconfidence lead to a Pareto improvement? The chapter continues by reviewing research on the impact of worker overconfidence on labor markets where workers can move between firms and where neither firms nor workers have discretion over wage setting. The chapter concludes with a summary of its main findings and a discussion of avenues for future research
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