20,581 research outputs found
New Measurements of Time-Dependent CP-Violating Asymmetries in b --> s Transitions at Belle
We present new measurements of CP-violation parameters in B0 --> phi K0, K+
K- Ks, f0(980) Ks, eta' Ks, omega Ks, Ks pi0, and K*0 gamma (K*0 --> Ks pi0)
decays 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 one of the specified decay
channels, and the flavor of the accompanying B meson is identified from its
decay products. CP-violation parameters for each of the decay modes are
obtained from the asymmetries in the distributions of the proper-time intervals
between the two B decays. All results are preliminary.Comment: 23 pages, 3 figures, submitted to ICHEP2004, Beijing, Chin
Studies of and Evidence of
We report studies of , using of
data collected at the resonance with the Belle detector at the
KEKB asymmetric storage ring. We measure the branching fraction for
to be , and find
an untagged charge asymmetry . We find the first evidence for with statistical significance and with a branching fraction
of .Comment: Submitted to International Europhysics Conference on High Energy
Physics, July 2003, Aachen, German
A measurement of the rate of wrong-sign decays D0 -> K+ pi-
A D0 meson can decay to K+ pi- through doubly Cabibbo-suppressed decay or via
D0-D0bar mixing. With 46.2 fb^{-1} of integrated luminosity collected by Belle,
we have measured the time integrated rate of the wrong-sign process D0 -> K+
pi- relative to that of the Cabibbo-favored process D0 -> K- pi+ to be R_WS =
(0.372 +- 0.025 +0.009/-0.014) % (preliminary). The D0-D0bar mixing parameters
can be derived from the time distribution of the wrong-sign process.Comment: Contributed to ICHEP2002/Amsterda
Search for the b --> d gamma process
We report search results for the flavor-changing neutral current process b
--> d gamma with a data sample containing 274 million B meson pairs accumulated
at the Upsilon(4S) resonance with the Belle detector at KEKB. We studied the
exclusive decays B- --> rho- gamma, B0bar --> rho0 gamma, and B0bar --> omega
gamma, and find no significant signal. We set an upper limit for a combined
branching fraction Br(B --> (rho,omega) gamma) < 1.4 x 10-6 at the 90%
confidence level, which is normalized to that of B- --> rho- gamma assuming an
isospin relation between the three modes.Comment: 10 pages, 2 figures, submitted to ICHEP2004, Beijing, Chin
Evidence for the Electroweak Penguin Decay }
We report a search for the flavor-changing neutral current decay using a 29.5 fb data sample accumulated at the
resonance with the Belle detector at the KEKB
storage ring. We observe evidence for and report the
preliminary branching fraction of {\cal B}(B \to K \mu^{+} \mu^{-}) =
(0.99^{+0.39}_{-0.32}^{+0.13}_{-0.15}) \times 10^{-6}. We also set the
following 90% confidence level upper limits on the branching fractions for
exclusive and inclusive decays, , , , , .Comment: Paper submitted to the 2001 Lepton Photon Conferenc
Search for B -> tau nu and B -> K nu nubar Decays with a Fully Reconstructed B at Belle
We present a search for the decays B -> tau nu and B -> K nu nubar in a 253
fb^-1 data sample collected at the Upsilon(4S) resonance with the Belle
detector at the KEKB asymmetric energy B factory. Combinatorial and continuum
backgrounds are suppressed by selecting a sample of events with one fully
reconstructed B. The decay products of the B on the other side of the event are
analyzed to search for B -> tau nu and B -> K nu nubar decays. We find no
significant evidence for a signal and set 90% confidence level upper limits of
B(B -> tau nu) K nu nubar) < 3.6*10^-5.Comment: 12 pages, 6 figures, submitted to the Lepton Photon 2005 conference
in Uppsala, Sweden and to the HEP2005 Europhysics Conference in Lisbon,
Portuga
Observation of Radiative B Meson Decays into Higher Kaonic Resonances
We have studied radiative B meson decays into higher kaonic resonances
decaying into a two-body or three-body final state, using a data sample of 21.3
fb recorded at the resonance with the Belle detector at
KEKB. For the two-body final state, we extract the component from an analysis of the helicity angle distribution, and
obtain . For the three-body final state, we observe a
signal that is consistent with a mixture of and . This is the first time that and have been observed separately. We find their branching fractions
to be and , respectively.Comment: Paper submitted to the 2001 Lepton Photon Conferenc
Measurement of the ratio Br(D0 --> pi+pi-pi0)/Br(D0 --> K-pi+pi0)
We report a high-statistics measurement of the relative branching fraction
Br(D0 --> pi+pi-pi0)/Br(D0 --> K-pi+pi0). A 357 inverse fb data sample
collected with the Belle detector at the KEKB asymmetric-energy e+e- collider
was used for the analysis. The relative branching fraction Br(D0 -->
pi+pi-pi0)/Br(D0 --> K-pi+pi0) is determined with an accuracy comparable to the
latest world average value.Comment: 13 pages, 10 figures, presented at the ICHEP06 Conference, Moscow,
Russia, a few typos correcte
Improved Measurements of Direct CP Violation in B --> K+pi-, K+pi0 and pi+pi0 Decays
We report an improved measurement of direct CP violation in the decay B0 -->
K+pi-, and a search for CP violation in the decays B+ --> K+pi0 and B+ -->
pi+pi0. The measured CP violating asymmetries are
Acp(K+pi-)=-0.113+-0.022(stat.)+-0.008(syst.),
Acp(K+pi0)=0.04+-0.04(stat.)+-0.02(syst.) and
Acp(pi+pi0)=0.02+-0.08(stat.)+-0.01(syst.), where the latter correspond to the
intervals -0.03<Acp(K+pi0)<0.11 and -0.12<Acp(pi+pi0)<0.15 at 90% confidence
level. These results are obtained from a data sample that contains 386 million
BBbar pairs that was collected near the Y(4S) resonance, with the Belle
detector at the KEKB asymmetric nergy e+e- collider. All of the results are
preliminary.Comment: 11 pages, 3 figures, submitted to the Lepton-Photon 2005 Conference
in Uppsala, Sweden and HEP2005 Europhysics Conference in Lisboa, Portuga
Improved Measurements of and Branching Fractions
We report on an improved study of
decays, based on events collected with the Belle
detector at KEKB. The following branching fractions have been measured: and
. We also obtain evidence with significance for with . No significant signal has been
found for the and decay modes, and upper limits at 90% CL are
presented.Comment: 9 pages, 3 figures, submitted to ICHEP2004, Beijing, Chin
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