55 research outputs found
Using to Probe Top Quark Couplings
Possible anomalous couplings of the top-quark to on-shell photons and gluons
are constrained by the recent results of the CLEO Collaboration on both
inclusive and exclusive radiative decays. We find that the process \bsg\
can lead to reasonable bounds on both the anomalous electric and magnetic
dipole moments of the top-quark, while essentially no limits are obtained on
the corresponding chromoelectric and chromomagnetic moments, which enter the
expression for the decay rate only through operator mixing.Comment: 10 pages plus 6 figures (available by request), LaTex,
ANL-HEP-PR-93-3
Supersymmetric with Large Chargino Contributions
Supersymmetric (SUSY) theories are often thought to give large branching
ratios for from charged Higgs loops. We show that in
many cases chargino loop contributions can cancel those of the Higgs, and SUSY
can give at or below the \SM\ prediction. We show
this occurs because the large stop mass splittings usually found in SUSY break
a GIM mechanism suppression. These effects are strongly enhanced by large
, so that is very sensitive to the value
of , contrary to what has been claimed. We also note that the
supergravity relation is somewhat disfavored over the general
case.Comment: TRI-PP-93-66. 12pp (Plain LATEX)+4 fig not incl. PostScript file of
figs available (~3MB), contact Corrie Kost [email protected]. Request hardcopy
or FAX of figures through [email protected]
Recalculation of QCD Corrections to Decay
We give a more complete calculation of decay, including
leading log QCD corrections from to in addition to corrections
from to . We have included the full set of dimension-6 operators
and corrected numerical mistakes of anomalous dimensions in a previous
paper\cite{Cho}. Comparing with the calculations without QCD running from
to \cite{Mis}, the inclusive decay rate is found to be enhanced.
At GeV, it results in 12\% enhancement, and for GeV, 15\% is
found. The total QCD effect makes an enhanced factor of 4.2 at GeV,
and 3.2 for GeV.Comment: 16 pages, 7 figures (uuencoded ps files), Changes of description. To
appear in Phys. Rev.
Multiplicity Distributions in Decays
The final states for the process have been
extensively discussed in the literature. Similarly-detailed analyses for the
case have not been performed. Generally this process
is searched for in 2-body decays such as . We present simple arguments to suggest that most of the time the
quark-level process will give rise to final states with rather high
multiplicities. Comments are made about the applicability of these results to
and hadronic decays.Comment: 11 pages, uuencoded postscript fil
Penguin-Diagram Induced Decays in the Standard Model and in the Two-Higgs-Doublet Model
We systematically analyse the gluonic penguin-induced charmless decays B \ra
K_X\phi( denotes the meson state ), in the
standard model and the two-Higgs-doublet model. These processes, being induced
at one-loop level, are of great importance in measuring the virtual top quark
effect in the standard model, and also in searching for the non-standard
signals in the low energy region. It is shown that the QCD effect is also
significant in these processes, as in the weak radiative processes B \ra X_s
\gamma. We also show that the charged Higgs contribution can not provide
sizable enhancements for the decays B \ra K_X\phi, in contrast to the decays
B \ra K_X\gamma. It is also found that processes such as B \ra
K_1(1400)\phi and B \ra K(1460)\phi have large branching fractions among B
\ra K_X\phi decays.Comment: 18pages, Latex. Paper (Hayashi, Takemi et al. AUE-02-93) is replaced
with reviced version Jan 1994 and aloso the title is change
Examination of the Resonance Contributions to Dileptonic Rare B-Decays
We analyse the long-distance contribution to
differential decay rate when the momentum dependence of and
- conversion strength is taken into account. The results
indicate that the resonance to nonresonance interference in the dilepton
invariant mass distribution is substantially reduced.Comment: 10 pages, Latex, one figure (included
Decay and Right-handed Top-bottom Charged Current
We introduce an anomalous top quark coupling (right-handed current) into
Standard Model Lagrangian. Based on this, a more complete calculation of decay including leading log QCD corrections from to
in addition to corrections from to is given. The inclusive decay
rate is found to be suppressed comparing with the case without QCD running from
to except at the time of small values of . e.g. when
, it is only of the value given before. As
goes smaller, this contribution is an enhancement like standard model case.
From the newly experiment of CLEO Collaboration, strict restrictions to
parameters of this top-bottom quark coupling are found.Comment: 20 Pages, 2 figures( ps file uuencoded)
Constraining the Two-Higgs-Doublet-Model parameter space
We confront the Two-Higgs-Doublet Model with a variety of experimental
constraints as well as theoretical consistency conditions. The most
constraining data are the \bar B\to X_s\gamma decay rate (at low values of
M_{H^\pm}), and \Delta\rho (at both low and high M_{H^\pm}). We also take into
account the B\bar B oscillation rate and R_b, or the width \Gamma(Z\to b\bar b)
(both of which restrict the model at low values of \tan\beta), and the
B^-\to\tau\nu_\tau decay rate, which restricts the model at high \tan\beta and
low M_{H^\pm}. Furthermore, the LEP2 non-discovery of a light, neutral Higgs
boson is considered, as well as the muon anomalous magnetic moment. Since
perturbative unitarity excludes high values of \tan\beta, the model turns out
to be very constrained. We outline the remaining allowed regions in the
\tan\beta-M_{H^\pm} plane for different values of the masses of the two
lightest neutral Higgs bosons, and describe some of their properties.Comment: 17 pages, 17 figure
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