85 research outputs found
Search for the decay at Belle
We report a search for the rare charmless decay
using a data sample of
pairs collected at the resonance with
the Belle detector at the KEKB asymmetric-energy collider. No
statistically significant signal is found and a 90% confidence-level upper
limit is set on the decay branching fraction as .Comment: 8 pages, 3 figures, submitted to PRD(RC
Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample
We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full
Belle data set of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct
one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay
in the remainder of the event. We observe no significant signal within the
phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu
gamma) mu+ nu gamma) l+ nu
gamma) < 3.5 x 10^-6 at 90 % credibility level.Comment: Submitted to Phys. Rev.
Semi-inclusive studies of semileptonic decays at Belle
We present an analysis of the semi-inclusive decays and , where denotes a final state that
may consist of additional hadrons or photons and is an electron or muon.
The studied decays are contained in the
data sample collected by the Belle detector at the KEKB
asymmetric-energy collider. The branching fractions of the decays are
measured to be and
, where the first two uncertainties
are statistical and systematic and the last is due to external parameters. The
measurement also provides an estimate of the
production cross-section, ,
at the center-of-mass energy .Comment: 13 pages, 2 figures, submitted to Phys. Rev.
Observation of in decays
We report the first observation of and
evidence for . We measure the product of
branching fractions for the former to be {\cal B}(B^0 \to X(3872) (K^+ \pi^-))
\times {\cal B}(X(3872) \to J/\psi \pi^+ \pi^-) = (7.9 \pm 1.3(\mbox{stat.})\pm
0.4(\mbox{syst.})) \times 10^{-6} and find that does not dominate the decay
mode. We also measure {\cal B}(B^+ \to X(3872) (K^0 \pi^+)) \times {\cal
B}(X(3872) \to J/\psi \pi^+ \pi^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm
0.9(\mbox{syst.})) \times 10^{-6}. This study is based on the full data sample
of 711~fb ( pairs) collected at the
resonance with the Belle detector at the KEKB collider.Comment: 7 pages, 3 figure
Evidence for the decay B0->eta pi^0
We report a search for the charmless hadronic decay with a
data sample corresponding to an integrated luminosity of 694
containing pairs. The data were collected by the
Belle experiment running on the resonance at the KEKB
collider. We measure a branching fraction
, where
the first uncertainty is statistical and the second is systematic. Our
measurement gives an upper limit of at 90\% confidence level. The signal has a significance of
standard deviations and constitutes the first evidence for this decay mode.Comment: 11 pages, 3 figures, 2 tables, submitted to Physical Review D(R
Observation of a new charged charmoniumlike state in B -> J/psi K pi decays
We present the results of an amplitude analysis of anti-B0 -> J/psi K- pi+
decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/psi pi+ is
observed with a significance of 6.2 sigma. The mass and width of the Zc(4200)+
are 4196 +31-29 +17-13 MeV/c^2 and 370 +70-70 +70-132 MeV, respectively; the
preferred assignment of the quantum numbers is J^P = 1^+. In addition, we find
evidence for Zc(4430)+ -> J/psi pi+. The analysis is based on a 711 fb^-1 data
sample collected by the Belle detector at the asymmetric-energy e+ e- collider
KEKB.Comment: 14 pages, 13 figure
Measurement of the direct asymmetry in decays with a lepton tag
We report the measurement of the direct asymmetry in the radiative
decay using a data sample of pairs collected at the resonance with
the Belle detector at the KEKB asymmetric-energy collider. The
asymmetry is measured as a function of the photon energy threshold. For
, where is the
photon energy in the center-of-mass frame, we obtain
,
consistent with the Standard Model prediction.Comment: Published at PR
Measurement of the branching ratio of relative to decays with hadronic tagging at Belle
We report a measurement of the branching fraction ratios R(D(*)) of Bbar ->
D(*) tau- nubar_tau relative to Bbar -> D()* l- nubar_l (where l = e or mu)
using the full Belle data sample of 772 x 10^6 BBbar pairs collected at the
Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e-
collider. The measured values are R(D)= 0.375 +- 0.064(stat.) +- 0.026(syst.)
and R(D*) = 0.293 +- 0.038(stat.) +- 0.015(syst.). The analysis uses hadronic
reconstruction of the tag-side B meson and purely leptonic tau decays. The
results are consistent with earlier measurements and do not show a significant
deviation from the standard model prediction.Comment: Accepted for publication in Phys.Rev.
Evidence of and search for double-charmonium production in and decays
Using data samples of and
events collected with the Belle detector, a first experimental
search has been made for double-charmonium production in the exclusive decays
, where , , , , and . No significant signal is
observed in the spectra of the mass recoiling against the reconstructed
or except for the evidence of production with a
significance of for . The
measured branching fraction \BR(\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}) is
. The
confidence level upper limits on the branching fractions of the other modes
having a significance of less than are determined. These results are
consistent with theoretical calculations using the nonrelativistic QCD
factorization approach.Comment: 12 pages, 4 figures, 1 table. The fit range was extended to include
X(4160) signal according to referee's suggestions. Other results unchanged.
Paper was accepted for publication as a regular article in Physical Review
- …