21 research outputs found
Applicability of Heavy Quark Effective Theory to the Radiative Decay
In the context of the observed decay the
applicability of the Heavy Quark Effective Theory (HQET), treating both b and s
as heavy quarks, is examined. We show that the heavy s-quark approximation, as
can be found in the literature, is not reliable.Comment: Plain LaTeX fil
Heavy quark production via supersymmetric interaction at a neutrino factory
We investigate b-quark production in both charged and neutral current
channels through neutrino-nucleon scattering at a neutrino factory, mediated by
the lepton flavour violating interactions present in a supersymmetric theory
with broken R-parity. Using values of the effctive interaction strengths well
below the current and projected experimental bounds, we are still able to
predict markedly enhanced event rates, especially for the neutral current
events which are not allowed at the lowest order in the standard model (SM).
Data from neutrino factories can therefore be used to probe strengths of such
interactions to considerably higher precision than what can be envisioned in
other experiments.Comment: Few typos are corrected in this versio
B-physics constraints on baryon number violating couplings: grand unification or R-parity violation
We investigate the role that baryon number violating interactions may play in
phenomenology. Present in various grand unified theories, supersymmetric
theories with R-parity violation and composite models, a diquark state could be
quite light. Using the data on B decays as well as mixing, we
find strong constraints on the couplings that such a light diquark state may
have with the Standard Model quarks.Comment: 19 pages, latex, no figures, 13 tables include
A nonsupersymmetric resolution of the anomalous muon magnetic moment
The recent result from the E821 experiment at BNL on the anomalous magnetic
moment of the muon shows a distinct discrepancy with the Standard Model
predictions. We calculate the additional correction that the anomalous magnetic
moment receives in a model with scalar leptoquarks. We find that such models
can account for the deviation from the SM value even for small leptoquark
couplings.Comment: 7 pages LaTex, 4 postscript figure
Dispersive Bounds on The Shape Of Lambda_b to Lambda_c l {\bar \nu_l} Formfactors
We derive a theoretically allowed domain for the charge radius and
curvature of the Isgur-Wise function describing the decay . Our method uses crossing symmetry, dispersion
relations and analyticity in the context of the Heavy Quark Effective Theory
but is independent of the specifics of any given model. The experimentally
determined values of the masses have been used as input information.
The results are of interest for testing different models employed to calculate
the heavy baryon formfactors which are used for the extraction of
from the experimental data.Comment: 18 pages, 1 figure included via psfi
Effects of Universal Extra Dimensions on Mixing
We study contributions coming to from one or more universal
extra dimensions (UED) in which all the Standard Model fields can propagate. In
the model with a single UED, the box diagrams for mixing are convergent and
therefore insensitive to the cutoff scale of the theory. In the case of two
UEDs, the result is not very sensitive to the cut-off scale due to GIM
mechanism. Within the present range of the parameters at level, the
lower bound on the compactification scale 1/R has been estimated to be 165 GeV
for one UED and 280 GeV for two UEDs. The bound increases drastically if one
can have a better determination of the meson decay constant and the
QCD correction parameter . For example, it rises to 740 GeV (for one UED)
if the error (at ) in the determination of from
quenched lattice calculation is reduced to one-third from its present value.
The UED contributions to the system are strongly suppressed.Comment: 12 pages, 1 postscript figure Some modifications, including the
correction of a computational error, with an effect of less than 20 per cent
change in the final result. A few references adde
b --> s gamma confronts B-violating scalar couplings: R-parity violating supersymmetry or diquark
We investigate the possible role that baryon number violating Yukawa
interactions may take in the inclusive decay . The
constraints, derived using the experimental results of the CLEO collaboration,
turn out, in many cases, to be more stringent than the existing bounds.Comment: 14 pages, late