1,807 research outputs found
An Upper Bound on the Decay tau -> mu gamma from Belle
We have performed a search for the lepton-flavor-violating decay tau -> mu
gamma using a data sample of 86.3fb^{-1} accumulated by the Belle detector at
KEK. No evidence for a signal is seen, and we set an upper limit for the
branching fraction of B(tau -> mu gamma) < 3.1 x 10^{-7} at the 90% confidence
level.Comment: 6 pages, 4 figuresm, submitted to Phys. Rev. Let
Search for B^- --> J/psi Lambda p-bar decay
We report the results of a search for B^{-} \to \jpsi \Lambda \pbar based
on a data set of 78 fb data collected at the resonance
with the Belle detector at the KEKB asymmetric collider. No
substantial signal is found, and we set the branching fraction upper limit
{\cal B}(B^{-} \to \jpsi \Lambda \pbar) < 4.1 \times 10^{-5} at 90%
confidence level.Comment: 8 pages, 2 figures, submitted to Phys. Rev.
Study of Exclusive B decays to Charmed Baryons
Using 29.1fb-1 of data accumulated at the Upsilon(4S) with the Belle detector
at KEKB, we have studied the decay modes B0bar->Lambda_c+ pbar pi+pi-, B- ->
Lambda_c+ pbar pi-, and B0bar ->Lambda_c+ pbar. We report branching fractions
of exclusive B decays to charmed baryons with four-, three- and two-body final
states, including intermediate Sigma_c++ and Sigma_c0 states. We observed B0bar
-> Sigma_c(2455)++pbar pi- for the first time with a branching fraction of
(2.38+0.63-0.55+-0.41+-0.62)x10-4 and observed evidence for the two-body decay
B- ->Sigma_c(2455)0 pbar with a branching fraction of
(0.45+0.26-0.19+-0.07+-0.12)x10-4. We also set improved upper limits for the
two-body decays B0bar -> Lambda_c+ pbar and B- -> Sigma_c(2520)0 pbar.Comment: accepted for publication in Phys. Rev.
Observation of -> DsJ*(2317)+ K- decay
The decays and
are studied for the first time. A significant signal is observed in the
decay channel with . No signals are observed in
the ,
and decay modes, and upper limits are
obtained. The analysis is based on a dataset of 140 fb collected by the
Belle experiment at the asymmetric collider KEKB.Comment: 9 pages, 2 figures, submitted to PR
An inclusive measurement of the photon energy spectrum in b->s gamma decays
We report a fully inclusive measurement of the flavour changing neutral
current decay b->s gamma in the energy range 1.8 GeV < E* < 2.8 GeV, covering
95% of the total spectrum. Using 140 fb^-1 we obtain BF(b->s gamma)= 3.55 +/-
0.32 +0.30-0.31 +0.11-0.07, where the errors are statistical, systematic and
from theory corrections. We also measure the first and second moments of the
photon energy spectrum above 1.8 GeV and obtain = 2.292 +/- 0.026 +/- 0.034
GeV and -^2 = 0.0305 +/- 0.0074 +/- 0.0063 GeV^2, where the errors are
statistical and systematic.Comment: RevTex4, 6 pages, Submitted to Phys.Rev.Lett. Replaced: added table
of systematic errors. New results take into account radiative J/Psi decay
Measurement of Time-Dependent CP-Violating Asymmetries in Decay
We present a measurement of CP-violation parameters in the B0 -> KsKsKs decay
based on a sample of 275 x 10^6 BBbar pairs collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider.
One neutral B meson is fully reconstructed in the decay B0 -> KsKsKs, and the
flavor of the accompanying B meson is identified from its decay products.
CP-violation parameters are obtained from the asymmetry in the distributions of
the proper-time interval between the two B decays: S = +1.26 +/- 0.68(stat) +/-
0.20(syst) and A = +0.54 +/- 0.34(stat) +/- 0.09(syst).Comment: 10 pages, 2 figures 10 pages, 2 figure
Observation of a narrow charmonium-like state in exclusive B+ -> K+ pi+pi- J/psi decays
We report the observation of a narrow charmonium-like state produced in the
exclusive decay process B+ -> K+ pi+pi- J/psi. This state, which decays into
pi+pi- J/psi, has a mass of 3872.0+-0.6(stat)+-0.5(syst) MeV, a value that is
very near the M_D + M_D* mass threshold. The results are based on an analysis
of 152M B-Bbar events collected at the Upsilon(4S) resonance in the Belle
detector at the KEKB collider. The statistical significance of the signal is in
excess of 10 sigma.Comment: 10 pages 4 figures, submitted to Physical Review Letter
Measurement of the mixing rate with partial reconstruction
We report a measurement of the mixing parameter
based on a sample of resonance decays
collected by the Belle detector at the KEKB asymmetric collider. We
use events with a partially reconstructed candidate and where the flavor of the accompanying meson is
identified by the charge of the lepton from a decay. The proper-time difference between the two mesons is
determined from the distance between the two decay vertices. From a
simultaneous fit to the proper-time distributions for the same-flavor
(, ) and opposite-flavor (,
) event samples, we measure the mass difference between the two
mass eigenstates of the neutral meson to be = .Comment: 16 pages, 14 figure
Study of B meson decays to three-body charmless hadronic final states
We report results of a study of charmless B meson decays to three-body KPiPi,
KKPi and KKK final states. Measurements of branching fractions for B decays to
K+0Pi+Pi-, K+K+K-, K0K+K-, KsKsK+ and KsKsKs final states are presented. The
decays B0=>K0K+K-, B+=>KsKsK+ and B0=>KsKsKs are observed for the first time.
We also report evidence for B+=>K+K-Pi+ decay. For the three-body final states
K0K+K-, KsKsPi+, K+K+Pi- and K-Pi+Pi+ 90% confidence level upper limits are
reported. Finally, we discuss the possibility of using the three-body
B0=>KsK+K- decay for CP violation studies. The results are obtained with a 78
fb^-1 data sample collected at the Y(4S) resonance by the Belle detector
operating at the KEKB asymmetric energy e+e- collider.Comment: 15 pages, 6 figures. To be submitted to PR
Measurement of Branching Fractions for Decays
We report measurements of branching fractions for charged and neutral decays where the meson is reconstructed in the and decay
channels. The neutral channel is a CP eigenstate and can be used to
measure the CP violation parameter . We also report the first
observation of the mode. The results are based on an
analysis of 29.1 fb of data collected by the Belle detector at KEKB.Comment: To appear in Physical Review Letter
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