337 research outputs found
New determination of the branching ratio of the structure dependent radiative decay
The branching ratio of the structure dependent (SD) radiative decay relative to that of the decay including the internal bremsstrahlung (IB) process
() has been measured in the J-PARC E36 experiment using plastic
scintillator/lead sandwich detectors. In the analysis, the effect of IB was
also taken into account in the SD radiative decay as . By combining the new data with the previously reported result of the E36
experiment using a CsI(Tl) calorimeter after revision for the IB correction for
, a new value has been determined, which is consistent
with a recent lattice QCD calculation, but larger than the expectation of
Chiral Perturbation Theory (ChPT) at order and the previous KLOE
value. Also, using the method to relate form factor and branching ratio
described in the KLOE paper, the present result is consistent with the form
factor prediction based on a gauged nonlocal chiral quark model, but larger
than ChPT at order .Comment: 19 page
Measurement of Time-Dependent CP-Violating Asymmetries in B0 --> phi Ks0, K+ K- Ks0, and eta' Ks0 Decays
We present an improved measurement of CP-violation parameters in B0 --> phi
Ks0, K+ K- Ks0, and eta' Ks0 decays based on a 140 fb-1 data sample 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
three modes are obtained from the asymmetries in the distributions of the
proper-time intervals between the two B decays. We find that the observed CP
asymmetry in the B0 --> phi Ks0 decay differs from the standard model (SM)
expectation by 3.5 standard deviations, while the other cases are consistent
with the SM.Comment: 10 pages, 4 postscript figures, submitted to Physical Review Letters,
also contributed to the XXI International Symposium on Lepton and Photon
Interactions at High Energies, Aug 11-16, 2003, Fermilab, Illinois US
Measurement of the CP Violation Parameter sin(2phi_1) in B^0_d Meson Decays
We present a measurement of the Standard Model CP violation parameter
sin(2phi_1) based on a 10.5 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric e+e- collider. One
neutral B meson is reconstructed in the J/psi K_S, psi(2S) K_S, chi_{c1} K_S,
eta_c K_S, J/psi K_L or J/psi pi^0 CP-eigenstate decay channel and the flavor
of the accompanying B meson is identified from its charged particle decay
products. From the asymmetry in the distribution of the time interval between
the two B-meson decay points, we determine sin(2phi_1) = 0.58 +0.32-0.34 (stat)
+0.09-0.10 (syst).Comment: LaTex, 13 pages, 3 figures, submitted to P.R.
A Measurement of Lifetime Difference in Meson Decays
We report a measurement of the - mixing parameter
using 23.4 fb of data collected near the (4S) resonance with
the Belle detector at KEKB. is measured from the lifetime difference
of mesons decaying into the state and the CP even eigenstate
. We find , where
the first error is statistical and the second systematic, corresponding to a
95% confidence interval .Comment: 10 pages, 3 figure
Precise Measurement of B Meson Lifetimes with Hadronic Decay Final States
The lifetimes of the B0bar and B- mesons are extracted from 29.1/fb of data
collected with the Belle detector at the KEK B-factory. A fit to the decay
length differences of neutral and charged B meson pairs, measured in events
where one of the B mesons is fully reconstructed in several hadronic modes,
yields tau_B0bar = 1.554 +/- 0.030(stat) +/- 0.019(syst) ps, tau_B- = 1.695 +/-
0.026(stat) +/- 0.015(syst) ps, and tau_B-/tau_B0bar = 1.091 +/- 0.023(stat)
+/- 0.014(syst).Comment: 10 pages, 2 figures, and 1 table. (To be) published in Phys. Rev.
Let
Observation of Large CP Violation in the Neutral B Meson System
We present a measurement of the Standard Model CP violation parameter sin
2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1
Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the
accompanying B meson is identified from its decay products. From the asymmetry
in the distribution of the time intervals between the two B meson decay points,
we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we
have observed CP violation in the neutral B meson system.Comment: 4 figures, to appear in Phys. Rev. Letter
Observation of the DsJ(2317) and DsJ(2457) in B decays
We report the first observation of the B --> Dbar DsJ(2317) and B --> Dbar
DsJ(2457) decays based on 123.8 10^6 BBar events collected with the Belle
detector at KEKB. We observe the DsJ(2317) decay to Ds pi0 and DsJ(2457) decay
to the Ds* pi0 and Ds gamma final states. We also set 90% CL upper limits for
the decays DsJ(2317) --> Ds* gamma, DsJ(2457) --> Ds* gamma, DsJ(2457) --> Ds
pi0 and DsJ(2457) --> Ds pi+ pi-.Comment: 6 pages, 3 figures. A few minor corrections. Replaced by version
accepted to publication in Phys. Rev. Let
Search for Charmless Two-body Baryonic Decays of B Mesons
We report the results of a search for the rare baryonic decays , , and . The analysis
is based on a data set of events collected by the
Belle detector at the KEKB collider. No statistically significant
signals are found, and we set branching fraction upper limits , , and at the 90% confidence level.Comment: 6 pages, 4 figures and 1 table. Submitted to Phys. Rev. D Rapid
Communication
Measurement of B0d - B0d-bar mixing rate from the time evolution of dilepton events at the Upsilon(4S)
We report a determination of the B0d - B0d-bar mixing parameter Delta-m_d
based on the time evolution of dilepton yields in Upsilon(4S) decays. The
measurement is based on a 5.9 /fb data sample collected by the Belle detector
at KEKB. The proper-time difference distributions for same-sign and
opposite-sign dilepton events are simultaneously fitted to an expression
containing Delta-m_d as a free parameter. Using both muons and electrons, we
obtain Delta-m_d = 0.463 +- 0.008(stat.) +- 0.016(sys.) ps^{-1} This is the
first determination of Delta-m_d from time evolution measurements at the
Upsilon(4S). We also place limits on possible CPT violations.Comment: 12 pages, 2 figure
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