2,417 research outputs found
Measurements of Charmless Hadronic b->s Penguin Decays in the pi+pi-K+pi- Final State and First Observation of B0 -> rho0K+pi-
We report measurements of charmless hadronic B^0 decays into the pi+pi-K+pi+
final state. The analysis uses a sample of 657x10^6 BBbar pairs collected with
the Belle detector at the KEKB asymmetric-energy e+e- collider at the Y(4S)
resonance. The decay B^0 -> rho0 Kpi is observed for the first time; the
significance is 5.0sigma and the corresponding partial branching fraction for
M_Kpi in (0.75,1.20) GeV/c^2 is [2.8 +- 0.5(stat) +-0.5(syst)] x 10^{-6}. We
also obtain the first evidence for B^0 -> f0Kpi with 3.5sigma significance and
for B^0 -> pi+pi-K*0 with 4.5sigma significance. For the two-body decays B^0 ->
rho0K*0 and B^0 -> f0K*0, the significances are 2.7sigma and 2.5sigma,
respectively, and the upper limits on the branching fractions are 3.4x10^{-6}
and 2.2x10^{-6} at 90% confidence level.Comment: 6 pages, 3 figures. accepted by PRD(RC
Measurement Of |V_ub| From Inclusive Charmless Semileptonic B Decays
We present the partial branching fraction for inclusive charmless
semileptonic B decays and the corresponding value of the CKM matrix element
|Vub|, using a multivariate analysis method to access ~90% of the B -> Xu l nu
phase space. This approach dramatically reduces the theoretical uncertainties
from the b-quark mass and non-perturbative QCD compared to all previous
inclusive measurements. The results are based on a sample of 657 million B
-Bbar pairs collected with the Belle detector. We find that Delta BR(B -> Xu l
nu; p^*B_l>1.0 GeV/c=1.963 x (1 +/- 0.088(stat.) +/- 0.081(sys.)) x 10^-3.
Corresponding values of |Vub| are extracted using several theoretical
calculations.Comment: 9 pages, 1 figure, 2 tables. Published in PR
Evidence for at Belle
We present a measurement of the branching fraction for the Cabibbo- and
color-suppressed decay based on a data sample of
events collected at the resonance
with the Belle detector at the KEKB asymmetric-energy collider. We
observe a signal of events with a significance of
including systematic uncertainties. The measured branching fraction is
.Comment: 5 pages, 5 figure
Observation of B+ -> Dbar*0 tau+ nu_tau and Evidence for B+ -> Dbar^0 tau+ nu_tau at Belle
We present measurements of B+ -> Dbar*0 tau+ nu_tau and B+ -> Dbar^0 tau+
nu_tau decays in a data sample of 657 x 10^6 BBbar pairs collected with the
Belle detector at the KEKB asymmetric-energy e+e- collider. We find
446^{+58}_{-56} events of the decay B+ -> Dbar*0 tau+ nu_tau with a
significance of 8.1 standard deviations, and 146^{+42}_{-41} events of the
decay B+ -> Dbar0 tau+ nu_tau with a significance of 3.5 standard deviations.
The latter signal provides the first evidence for this decay mode. The measured
branching fractions are B(B+ -> Dbar*0 tau+ nu_tau)=(2.12^{+0.28}_{-0.27}
(stat) +- 0.29 (syst)) % and B(B+ -> Dbar0 tau+ nu_tau)=(0.77 +- 0.22 (stat) +-
0.12 (syst)) %.Comment: 6 pages, 4 figures, submitted to Phys. Rev. Let
Search for the X(1812) in
We report on a search for the X(1812) state in the decay with a data sample of pairs collected
with the Belle detector at the KEKB collider. No significant signal is
observed. An upper limit (90% C.L.) is determined. We also constrain the
three-body decay branching fraction to be 1.9 (90% C.L.).Comment: 5pages,2 figures(3 figure files). submitted to PRD(RC
Dalitz analysis of B --> K pi psi' decays and the Z(4430)+
From a Dalitz plot analysis of B --> K pi psi' decays, we find a signal for
Z(4430)+ --> pi+ psi' with a mass M= (4443(+15-12)(+19-13))MeV/c^2, width
Gamma= (107(+86-43)(+74-56))MeV, product branching fraction BR(B0 --> K-
Z(4430)+) x BR(Z(4430)+ --> pi+ psi')= (3.2(+1.8-0.9)(+5.3-1.6)) x 10^{-5}, and
significance of 6.4sigma that agrees with previous Belle measurements based on
the same data sample. In addition, we determine the branching fraction BR(B^0
--> K*(892)^0 psi')= (5.52(+0.35-0.32)(+0.53-0.58)) x 10^{-4} and the fraction
of K*(892)^0 mesons that are longitudinally polarized f_L=
44.8(+4.0-2.7)(+4.0-5.3)%. These results are obtained from a 605fb^{-1} data
sample that contains 657 million B-anti-B pairs collected near the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric energy e+e- collider.Comment: Final version published in PRD(RC
Study of the decay
We present a study of with X(3872) decaying to using a sample of 657 million pairs recorded at the
resonance with the Belle detector at the KEKB asymmetric-energy
collider. Both and decay
modes are used. We find a peak of events with a mass of
, a width of and a product branching fraction , where the first errors are statistical
and the second ones are systematic. The significance of the signal is
. The difference between the fitted mass and the
threshold is calculated to be . We
also obtain an upper limit on the product of branching fractions of at
90% CL.Comment: 7 pages, 3 figures, BELLE-CONF-0832 contributed to ICHEP 2008,
revised and submitted to Phys. Rev. D R
Measurement of Inclusive Radiative B-meson Decays with a Photon Energy Threshold of 1.7 GeV
Using 605/fb of data collected at the Upsilon(4S) resonance we present a
measurement of the inclusive radiative B-meson decay channel, B to X_s gamma.
For the lower photon energy thresholds of 1.7, 1.8, 1.9 and 2.0GeV, as defined
in the rest frame of the B-meson, we measure the partial branching fraction and
the mean and variance of the photon energy spectrum. At the 1.7GeV threshold we
obtain the partial branching fraction BF(B to X_s gamma) = (3.45 +/- 0.15 +/-
0.40) x 10^-4, where the errors are statistical and systematic.Comment: 9 pages, 3 figures, 2 table
Search for CP violation in the decays and
We have searched for CP violation in the charmed meson decays and using 673 fb of data
collected with the Belle detector at the KEKB asymmetric-energy
collider. No evidence for CP violation is observed. We report the most
sensitive CP asymmetry measurements to date for these decays: , , , and , where the first uncertainties are statistical and
the second are systematic
Measurement of CP asymmetries in decays
We report measurements of CP violation parameters in
decays based on a data sample of pairs collected
with the Belle detector at the KEKB asymmetric-energy collider. We
use decays for both mixing-induced and direct
violating asymmetry measurements and decays for the
direct CP violation measurement. The CP violation parameters obtained are and
. The
branching fraction of decay is measured to be
. The observed value
differs by 1.9 standard deviations from the value expected from an isospin sum
rule.Comment: 6 pages, 3 figure
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