57 research outputs found
Factorization of the charge correlation function in oscillations
Extraction of the mass difference from oscillations
involves tagging of bottom flavour at production and at decay. We show that the
asymmetry between the unmixed and mixed events factorizes into two parts, one
depending on the production-tag and the other on the decay-tag.Comment: 6 pages, Latex, no figure
Decay
Motivated by the experimental measurement of the decay rate, , and
the longitudinal polarization, , in the Cabibbo favored decay , we have studied theoretical prediction within the context of
factorization approximation invoking several form factors models. We were able
to obtain agreement with experiment for both and by using
experimentally measured values of the form factors ,
and in the semi-leptonic decay . We have also included in our calculation the effect of the
final state interaction () by working with the partial waves amplitudes
, and . Numerical calculation shows that the decay amplitude is
dominated by wave, and that the polarization is sensitive to the
interference between and waves. The range of the phase difference
accommodated by experimental error in
is large.Comment: 7 pages, LaTe
Constraining the CKM Parameters using CP Violation in semi-leptonic B Decays
We discuss the usefulness of the CP violating semi-leptonic asymmetry a_{SL}
not only as a signal of new physics, but also as a tool in constraining the CKM
parameters. We show that this technique could yield useful results in the first
years of running at the B factories. We present the analysis graphically in
terms of M_{12}, the dispersive part of the B-Bbar mixing amplitude. This is
complementary to the usual unitarity triangle representation and often allows a
cleaner interpretation of the data.Comment: 15 pages REVTEX, 7 figure
Measuring the Photon Helicity in Radiative B Decays
We propose a way of measuring the photon polarization in radiative B decays
into K resonance states decaying to K\pi\pi, which can test the Standard Model
and probe new physics. The photon polarization is shown to be measured by the
up-down asymmetry of the photon direction relative to the K\pi\pi decay plane
in the K resonance rest frame. The integrated asymmetry in K_1(1400)\to
K\pi\pi, calculated to be 0.34\pm 0.05 in the Standard Model, is measurable at
currently operating B factories.Comment: 4 pages, final version to appear in Physical Review Letter
Probing SUSY-induced CP violations at B factories
In the minimal supersymmetric standard model (MSSM), the \mu-parameter and
the trilinear coupling A_t may be generically complex and can affect various
observables at B factories. Imposing the edm constraints, we find that there is
no new large phase shift in the B^0 - \bar{B^0} mixing, CP violating dilepton
asymmetry is smaller than 0.1 %, and the direct CP violation in B\to X_s \gamma
can be as large as \sim \pm 16 %.Comment: 4 pages, 2 figures. Version to appear in Phys. Rev. Let
Heavy Mesons in Two Dimensions
The large mass limit of QCD uncovers symmetries that are not present in the
QCD lagrangian. These symmetries have been applied to physical (finite mass)
systems, such as B and D mesons.
We explore the validity of this approximation in the 't Hooft model
(two-dimensional QCD in the large-N approximation). We find that the large mass
approximation is good, even at the charm mass, for form factors, but it breaks
down for the pseudoscalar decay constant.Comment: 4 pages, 3 figures inc
Radiative B decays to the axial mesons at next-to-leading order
We calculate the branching ratios of at next-to-leading
order (NLO) of where is the orbitally excited axial vector
meson. The NLO decay amplitude is divided into the vertex correction and the
hard spectator interaction part. The one is proportional to the weak form
factor of transition while the other is a convolution between
light-cone distribution amplitudes and hard scattering kernel. Using the
light-cone sum rule results for the form factor, we have \calB(B^0\to
K_1^0(1270)\gamma)=(0.828\pm0.335)\times 10^{-5} and \calB(B^0\to
K_1^0(1400)\gamma)=(0.393\pm0.151)\times 10^{-5}.Comment: 17pages, 4 figures. Minor changes, typos corrected. PRD accepted
versio
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
Towards a Model-Independent Analysis of Rare Decays
Motivated by the experimental accessibility of rare decays in the ongoing
and planned experiments, we propose to undertake a model-independent analysis
of the inclusive decay rates and distributions in the processes \bgamaxs~ and
\Bsell ~( or ). We show how measurements of the decay rates and
distributions in these processes would allow us to extract the magnitude and
sign of the dominant Wilson coefficients of the magnetic moment operator \mb
\bar{s}_L \sigma_{\mu \nu} b_R F^{\mu \nu } and the four-fermion operators
and . Non-standard-model
effects could thus manifest themselves at low energy in rare decays through
the Wilson coefficient having values distinctly different from their
standard-model counterparts. We illustrate this possibility using the examples
of the two-doublet Higgs models and the minimal supersymmetric models. The
dilepton invariant mass spectrum and the forward-backward asymmetry of
in the centre-of-mass system of the dilepton pair in the decay \Bsell ~are also
worked out for the standard model and some representative solutions for the
other two models.Comment: LaTeX, 36 pages, 11 figures appended after \end{document} as
uu-encoded and compressed .eps files, uses epsf, CERN-TH.7346/9
Factorization and Nonfactorization in B Decays
Using NLL values for Wilson coefficients and including the contributions from
the penguin diagrams, we estimate the amount of nonfactorization in two-body
hadronic B decays. Also, we investigate the model dependence of the
nonfactorization parameters by performing the calculation using different
models for the form factors. The results support the universality of
nonfactorizable contributions in both Cabibbo-favored and Cabibbo-suppressed B
decays.Comment: 17 pages, 5 figures, revte
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