2,886 research outputs found
Evidence for B to K eta' gamma Decays at Belle
We present the results of a search for the radiative decay (B -> K eta'
gamma) and find evidence for (B^+ -> K^+ eta' gamma) decays at the 3.3 standard
deviation level with a partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x
10e-6, where the first error is statistical and the second systematic. This
measurement is restricted to the region of combined (K eta') invariant mass
less than 3.4GeVc^2. A 90% confidence level upper limit of 6.4 x 10e-6 is
obtained for the decay (B^0 -> K^0 eta' gamma) in the same (K eta') invariant
mass region. These results are obtained from a 605 fb^-1 data sample containing
657 x 10e6 B anti-B pairs collected at the Upsilon(4S) resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider.Comment: 5 pages, 4 figures. Submitted to PRD-RC on 6/8/0
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
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
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
Evidence of time-dependent CP violation in the decay B0 to D*+D*-
We report a measurement of the CP-odd fraction and the time-dependent CP
violation in B0 to D*+D*- decays, using 657.10^6 BBbar events collected at the
Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy
e+e- collider. We measure a CP-odd fraction of
Rperp=0.125+/-0.043(stat)+/-0.023(syst). From the distributions of the
proper-time intervals between a B0to D*+D*- decay and the other B meson in the
event, we obtain evidence of CP violation with measured parameters
AD*+D*-=0.15+/-0.13(stat)+/-0.04(syst) and
SD*+D*-=-0.96+/-0.25(stat)-0.16+0.13(syst).Comment: Published in PR
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.
Evidence for direct CP violation in the decay B->D(*)K, D->KsPi+Pi- and measurement of the CKM phase phi3
We present a new measurement of the unitarity triangle angle phi3 using a
Dalitz plot analysis of the KsPi+Pi- decay of the neutral D meson produced in
B->D(*)K decays. The method exploits the interference between D0 and D0bar to
extract the angle phi3, strong phase delta and the ratio r of suppressed and
allowed amplitudes. We apply this method to a 605 fb-1 data sample collected by
the Belle experiment. The analysis uses three decays: B->DK, and B->D*K with
D*->DPi0 and D*->Dgamma, as well as the corresponding charge-conjugate modes.
From a combined maximum likelihood fit to the three modes, we obtain phi3 =
78.4^+10.8_-11.6 +- 3.6 (syst) +- 8.9 (model) degrees. CP conservation in this
process is ruled out at the confidence level (1-CL)=5x10^-4, or 3.5 standard
deviations.Comment: 10 pages, 5 figures, 4 tables. Replaced by version published in Phys.
Rev.
Observation of the and the Y(2175) in
The cross sections for and e^+ e^- \to \phi
\fzero are measured from threshold to using
initial state radiation. The analysis is based on a data sample of 673
fb collected on and below the resonance with the Belle
detector at the KEKB asymmetric-energy collider. First measurements
are reported for the resonance parameters of the in the
mode: MeV/ and MeV/. A structure at ,
corresponding to the so called Y(2175), is observed; its mass and width are
determined to be MeV/ and , respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC
Search for Lepton-Flavor-Violating tau Decays into a Lepton and an f0(980) Meson
We search for lepton-flavor-violating tau decays into a lepton (electron or
muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle
detector at the KEKB asymmetric-energy e+e- collider. No events are observed
and we set the following 90% C.L. upper limits on the branching fraction
products: B(tau- -> e-f0(980))*B(f0(980)->pi+pi-)
mu-f0(980))*B(f0(980) -> pi+pi-)<3.4x10^-8. This is the first search performed
for these modes.Comment: 10 pages, 4 figures, submitted to Phys. Lett.
Measurement of the e+e- --> D0D*-pi+ cross section using initial-state radiation
We report measurements of the exclusive cross section for e+e- --> D0D*-pi+
as function of center-of-mass energy from the D0D*-pi+ threshold to 5.2 GeV
with initial-state radiation. No evidence is found for Y(4260)-->D0D*-pi+
decays. The analysis is based on a data sample collected with the Belle
detector at or near a center-of-mass energy of 10.58 GeV with an integrated
luminosity of 695 1/fb at the KEKB asymmetric-energy e+e- collider.Comment: 7 pages, 3 figures, presented at EPS09 and LP09 conference
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