29 research outputs found
Supersymmetric Contributions to Bs->K+K-
Inspired by the existing calculation of B->piK decays in supersymmetry
(SUSY), we evaluate the dominant SUSY contributions to Bs->K+K-. We show that
the observables of this process can be significantly modified in the presence
of SUSY. In particular, the branching ratio can be increased considerably
compared to the prediction of the standard model (SM). The effect is even more
dramatic for the CP-violating asymmetries A_dir and A_mix. These asymmetries,
expected to be small in the SM (A_dir is predicted to take only positive
values), change drastically with SUSY contributions. The measurement of these
observables can therefore be used to detect the presence of physics beyond the
SM, and put constraints on its parameters.Comment: 17 pages, 2 figures. This new version contains one added reference
and some minor style change
First ADS analysis of B- -> D0K- decays in hadron collisions
Proceedings of DISCRETE 2010, Symposium on Prospects in the Physics of
Discrete Symmetries, Rome (IT), 6-11 December 2010Comment: 7 pages, 5 figure
Role of electromagnetic dipole operator in the electroweak penguin dominated vector meson decays of meson
The pure annihilation type decays and
receive only color suppressed penguin contributions with a very small branching
ratio in the standard model. When we include the previously neglected
electromagnetic dipole operator, the branching ratios can be enhanced one order
magnitude larger than previous study using QCD factorization approach. That is
and . The new effect can also give
a large contribution, of order , to transverse polarization of
and which is comparable to the longitudinal
part. These effects can be detected in the LHCb experiment and the Super-B
factories.Comment: Revised extensively. 8 pages, 4 figure
Footprints of the Beyond in flavor physics: Possible role of the Top Two Higgs Doublet Model
The B-factories results provide an impressive confirmation of the Standard
Model (SM) description of flavor and CP violation. Nevertheless, as more data
were accumulated, deviations in the 2.5-3.5 sigma range have emerged pointing
to the exciting possibility of new CP-odd phase(s) and flavor violating
parameters in B-decays. Primarily this seems to be the case in the time
dependent CP asymmetries in penguin dominated modes (e.g. B -> phi (eta') Ks).
We discuss these and other deviations from the SM and, as an illustration of
possible new physics scenarios, we examine the role of the Top Two Higgs
Doublet Model. This is a simple extension of the SM obtained by adding second
Higgs doublet in which the Yukawa interactions of the two Higgs doublets are
assigned in order to naturally account for the large top-quark mass.
Of course, many other extensions of the Standard Model could also account for
these experimental deviations. Clearly if one takes these deviations seriously
then some new particles in the 300 GeV to few TeV with associated new CP-odd
phase(s) are needed.Comment: 40 pages, 17 figures (png format), uses pdflate
Implications for the Constrained MSSM from a new prediction for b to s gamma
We re-examine the properties of the Constrained MSSM in light of updated
constraints, paying particular attention to the impact of the recent
substantial shift in the Standard Model prediction for BR(B to X_s gamma). With
the help of a Markov Chain Monte Carlo scanning technique, we vary all relevant
parameters simultaneously and derive Bayesian posterior probability maps. We
find that the case of \mu>0 remains favored, and that for \mu<0 it is
considerably more difficult to find a good global fit to current constraints.
In both cases we find a strong preference for a focus point region. This leads
to improved prospects for detecting neutralino dark matter in direct searches,
while superpartner searches at the LHC become more problematic, especially when
\mu<0. In contrast, prospects for exploring the whole mass range of the
lightest Higgs boson at the Tevatron and the LHC remain very good, which
should, along with dark matter searches, allow one to gain access to the
otherwise experimentally challenging focus point region. An alternative measure
of the mean quality-of-fit which we also employ implies that present data are
not yet constraining enough to draw more definite conclusions. We also comment
on the dependence of our results on the choice of priors and on some other
assumptions.Comment: JHEP versio
Neural network parametrization of the lepton energy spectrum in semileptonic B meson decays
We construct a parametrization of the lepton energy spectrum in inclusive
semileptonic decays of B mesons, based on the available experimental
information: moments of the spectrum with cuts, their errors and their
correlations, together with kinematical constraints. The result is obtained in
the form of a Monte Carlo sample of neural networks trained on replicas of the
experimental data, which represents the probability density in the space of
lepton energy spectra. This parametrization is then used to extract the b quark
mass m_b^{1S} in a way that theoretical uncertainties are minimized, for which
the value m_b^{1S}=4.84 \pm 0.14^{exp}\pm 0.05^{th} GeV is obtained.Comment: 32 pages, 22 figures, JHEP3 class. v4 version accepted for
publication in JHE
The 2004 UTfit Collaboration Report on the Status of the Unitarity Triangle in the Standard Model
Using the latest determinations of several theoretical and experimental
parameters, we update the Unitarity Triangle analysis in the Standard Model.
The basic experimental constraints come from the measurements of |V_ub/V_cb|,
Delta M_d, the lower limit on Delta M_s, epsilon_k, and the measurement of the
phase of the B_d - anti B_d mixing amplitude through the time-dependent CP
asymmetry in B^0 to J/psi K^0 decays. In addition, we consider the direct
determination of alpha, gamma, 2 beta + gamma and cos(2 beta) from the
measurements of new CP-violating quantities, recently performed at the B
factories. We also discuss the opportunities offered by improving the precision
of the various physical quantities entering in the determination of the
Unitarity Triangle parameters. The results and the plots presented in this
paper can also be found at http://www.utfit.org, where they are continuously
updated with the newest experimental and theoretical results.Comment: 32 pages, 17 figures. High resolution figures and updates can be
found at http://www.utfit.org v2: misprints correcte
B_s - \bar{B}_s mixing in the MSSM scenario with large flavor mixing in the LL/RR sector
We show that the recent measurements of mass difference,
, by D{\O} and CDF collaborations give very strong constraints on
MSSM scenario with large flavor mixing in the LL and/or RR sector of down-type
squark mass squared matrix. In particular, the region with large mixing angle
and large mass difference between scalar strange and scalar bottom is ruled out
by giving too large . The allowed region is sensitive to the CP
violating phases . The constraint is most stringent
on the scenario with both LL and RR mixing. We also predict the time-dependent
CP asymmetry in decay and semileptonic asymmetry in decay.Comment: 15 pages, 9 figure
On the detectability of the CMSSM light Higgs boson at the Tevatron
We examine the prospects of detecting the light Higgs h^0 of the Constrained
MSSM at the Tevatron. To this end we explore the CMSSM parameter space with
\mu>0, using a Markov Chain Monte Carlo technique, and apply all relevant
collider and cosmological constraints including their uncertainties, as well as
those of the Standard Model parameters. Taking 50 GeV < m_{1/2}, m_0 < 4 TeV,
|A_0| < 7 TeV and 2 < tan(beta) < 62 as flat priors and using the formalism of
Bayesian statistics we find that the 68% posterior probability region for the
h^0 mass lies between 115.4 GeV and 120.4 GeV. Otherwise, h^0 is very similar
to the Standard Model Higgs boson. Nevertheless, we point out some enhancements
in its couplings to bottom and tau pairs, ranging from a few per cent in most
of the CMSSM parameter space, up to several per cent in the favored region of
tan(beta)\sim 50 and the pseudoscalar Higgs mass of m_A\lsim 1 TeV. We also
find that the other Higgs bosons are typically heavier, although not
necessarily much heavier. For values of the h^0 mass within the 95% probability
range as determined by our analysis, a 95% CL exclusion limit can be set with
about 2/fb of integrated luminosity per experiment, or else with 4/fb (12/fb) a
3 sigma evidence (5 sigma discovery) will be guaranteed. We also emphasize that
the alternative statistical measure of the mean quality-of-fit favors a
somewhat lower Higgs mass range; this implies even more optimistic prospects
for the CMSSM light Higgs search than the more conservative Bayesian approach.
In conclusion, for the above CMSSM parameter ranges, especially m_0, either
some evidence will be found at the Tevatron for the light Higgs boson or, at a
high confidence level, the CMSSM will be ruled out.Comment: JHEP versio
A Collider Signature of the Supersymmetric Golden Region
Null results of experimental searches for the Higgs boson and the
superpartners imply a certain amount of fine-tuning in the electroweak sector
of the Minimal Supersymmetric Standard Model (MSSM). The "golden region" in the
MSSM parameter space is the region where the experimental constraints are
satisfied and the amount of fine-tuning is minimized. In this region, the stop
trilinear soft term is large, leading to a significant mass splitting between
the two stop mass eigenstates. As a result, the decay of the heavier stop into
the lighter stop and a Z boson is kinematically allowed throughout the golden
region. We propose that the experiments at the Large Hadron Collider (LHC) can
search for this decay through an inclusive signature, Z+2jb+missing Et+X. We
evaluate the Standard Model backgrounds for this channel, and identify a set of
cuts that would allow detection of the supersymmetric contribution at the LHC
for the MSSM parameters typical of the golden region. We also discuss other
possible interpretations of a signal for new physics in the Z+2jb+missing Et+X
channel, and suggest further measurements that could be used to distinguish
among these interpretations.Comment: 23 pages, 5 figures. New in v4: an error fixed in Eq. (13); results
unaffecte