1,509 research outputs found
Newly observed two-body decays of B mesons in a hybrid perspective
In consistency with the b --> c type of (quasi) two body decays, recently
observed two body decays of B mesons are studied in a hybrid perspective in
which their amplitude is given by a sum of factorizable and non-factorizable
ones, and a role of the latter in these decays are discussed.Comment: 7 page
Lifetime Difference and Endpoint effect in the Inclusive Bottom Hadron Decays
The lifetime differences of bottom hadrons are known to be properly explained
within the framework of heavy quark effective field theory(HQEFT) of QCD via
the inverse expansion of the dressed heavy quark mass. In general, the spectrum
around the endpoint region is not well behaved due to the invalidity of
expansion near the endpoint. The curve fitting method is adopted to treat the
endpoint behavior. It turns out that the endpoint effects are truly small and
the explanation on the lifetime differences in the HQEFT of QCD is then well
justified. The inclusion of the endpoint effects makes the prediction on the
lifetime differences and the extraction on the CKM matrix element
more reliable.Comment: 11 pages, Revtex, 10 figures, 6 tables, published versio
Hadronic decays of B involving a tensor meson through a transition
We re-analyze hadronic decays of B mesons to a pseudoscalar (P) and a tensor
meson (T), or a vector meson (V) and a tensor meson, through a
transition. We discuss possible large uncertainties to branching ratios (BR's)
of the relevant modes, mainly arising from uncertainties to the hadronic form
factors for the transition. The BR's and CP asymmetries for and VT decays are then calculated by using the form factors given in the
ISGW2 model (the improved version of the original Isgur-Scora-Grinstein-Wise
(ISGW) model). We find that the estimated BR's of many modes are increased by
an order of magnitude, compared to the previous results calculated within the
ISGW model.Comment: 22 pages, LaTex; minor clarifications included; to appear in Phys.
Rev.
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
Understanding the newly observed Y(4008) by Belle
Very recently a new enhancement around 4.05 GeV was observed by Belle
experiment. In this short note, we discuss some possible assignments for this
enhancement, i.e. and molecular state. In these two
assignments, Y(4008) can decay into with comparable
branching ratio with that of . Thus one suggests
high energy experimentalists to look for Y(4008) in channel.
Furthermore one proposes further experiments to search missing channel
, and especially and
, which will be helpful to distinguish and
molecular state assignments for this new enhancement.Comment: 4 pages, 5 figures. Typos correcte
Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in
We argue that one can search for physics beyond the standard model through
measurements of the isospin-violating quantity , its charge conjugate
, and direct CP violation in the partial decay rates of . We illustrate this by working out theoretical profiles of the
charge-conjugate averaged ratio and the CP asymmetry in the
standard model and in some variants of the minimal supersymmetric standard
model. We find that chargino contributions in the large region may
modify the magnitudes and flip the signs of and compared to their standard-model values, providing an
unmistakeable signature of supersymmetry.Comment: 10 pages, 7 figures (requires graphicx
QCD-based description of one-particle inclusive B decays
We discuss one-particle inclusive B decays in the limit of heavy b and c
quarks. Using the large-N_C limit we factorize the non-leptonic matrix
elements, and we employ a short distance expansion. Modeling the remaining
nonperturbative matrix elements we obtain predictions for various decay
channels and compare them with existing data.Comment: LaTeX, 22 pages, 6 figures (eps); analytical and numerical results
unchanged, misrepresentation of experimental data in Fig. 5 corrected, final
published versio
Heavy Baryon Production and Decay
The branching ratio B(Lambda_c -> p K- pi+) normalizes the production and
decay of charmed and bottom baryons. At present, this crucial branching ratio
is extracted dominantly from B.bar -> baryons analyses. This note questions
several of the underlying assumptions and predicts sizable B.bar -> D(*) N
N'.bar X transitions, which were traditionally neglected. It predicts
B(Lambda_c -> p K- pi+) to be significantly larger (0.07 +/- 0.02) than the
world average. Some consequences are briefly mentioned. Several techniques to
measure B(Lambda_c -> p K- pi+) are outlined with existing or soon available
data samples. By equating two recent CLEO results, an appendix obtains B(D0 ->
K- pi+)= 0.035 +/- 0.002, which is somewhat smaller than the current world
average.Comment: 27 pages, 4 eps figures, revte
Implications of Recent Measurements
The recent measurements of the color-suppressed modes imply non-vanishing relative final-state interaction (FSI)
phases among various decay amplitudes. Depending on whether or
not FSIs are implemented in the topological quark-diagram amplitudes, two
solutions for the parameters and are extracted from data using
various form-factor models. It is found that is not universal:
and with a relative phase
of order between and . If FSIs are not included in
quark-diagram amplitudes from the outset, and
will become smaller. The large value of compared to
or naive expectation implies the importance of
long-distance FSI contributions to color-suppressed internal -emission via
final-state rescatterings of the color-allowed tree amplitude.Comment: 17 pages. The Introduction is substantially revised and the order of
the presentation in Sec. 2 is rearranged. To appear in Phys. Re
Tau and Charm physics highlights
In tau physics, we are at the frontier between the completion of the LEP
program and the start of analyses from b-factories, which are expected to
produce results in the coming years. Nice results from CLEO are steadily
delivered in the meantime. For charm, impressive progress have been achieved by
fixed target experiments in the search for CP violation and D^0 - \bar D^0
oscillations. First results from b-factories demonstrate the power of these
facilities in such areas. The novel measurement of the D* width by CLEO happens
to be rather different from current expectations. The absence of a charm
factory explains the lack or the very slow progress in the absolute scale
determinations for charm decays.Comment: "Typos corrected and references added
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