398 research outputs found
Measurement of the Branching Fraction of the Decay in Fully Reconstructed Events at Belle
We present an analysis of the exclusive
decay, where represents an
electron or a muon, with the assumption of charge-conjugation symmetry and
lepton universality. The analysis uses the full data sample
collected by the Belle detector, corresponding to 711 fb of integrated
luminosity. We select the events by fully reconstructing one meson in
hadronic decay modes, subsequently determining the properties of the other
meson. We extract the signal yields using a binned maximum-likelihood fit to
the missing-mass squared distribution in bins of the invariant mass of the two
pions or the momentum transfer squared. We measure a total branching fraction
of , where the
uncertainties are statistical and systematic, respectively. This result is the
first reported measurement of this decay.Comment: 23 pages, 19 figure
Evidence for a vector charmonium-like state in
We report the measurement of via
initial-state radiation using a data sample of an integrated luminosity of
921.9 fb collected with the Belle detector at the and
nearby. We find evidence for an enhancement with a 3.4 significance in
the invariant mass of The measured mass and width
are
and ,
respectively. The mass, width, and quantum numbers of this enhancement are
consistent with the charmonium-like state at 4626 MeV/ recently reported
by Belle in The product of the cross section and the branching fraction of
is measured from
threshold to 5.6 GeV.Comment: 9 pages, 4 figure
Measurement of the CKM Matrix Element from at Belle
We present a new measurement of the CKM matrix element from decays, reconstructed with the full Belle data set
of integrated luminosity. Two form factor
parameterizations, originally conceived by the Caprini-Lellouch-Neubert (CLN)
and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product
and the decay form factors, where
is the normalization factor and is a small
electroweak correction. In the CLN parameterization we find
, , , . For the BGL parameterization we
obtain , which is consistent with the World Average when correcting for
. The branching fraction of is measured to be . We also present a new
test of lepton flavor universality violation in semileptonic decays,
. The errors correspond to the statistical and
systematic uncertainties respectively. This is the most precise measurement of
and form factors to date and the first
experimental study of the BGL form factor parameterization in an experimental
measurement
Measurement of the branching fraction of at Belle
Based on a data sample of 983 fb collected with the Belle detector at
the KEKB asymmetric-energy collider, we present the study of the
heavy-flavor-conserving decay with
reconstructed via its decay mode. The
branching fraction ratio is measured
to be . Combing with the world average value of
, the branching fraction
is deduced to be . Here, the uncertainties above are statistical,
systematic, and from , respectively.Comment: 5 pages, 4 figure
Search for B decays to invisible final states ( +γ) at Belle
We report searches for and decays, where the energy of the photon is required to be larger than 0.5 GeV. These results are obtained from a data sample that contains pairs and was collected near the resonance with the Belle detector at the KEKB collider. We observe no significant signal for either decay and set upper limits on their branching fractions at confidence level of and
Measurement of Angular Coefficients of : Implications for and Tests of Lepton Flavor Universality
We measure the complete set of angular coefficients for exclusive
decays (). Our analysis
uses the full Belle data set with hadronic tag-side
reconstruction. The results allow us to extract the form factors describing the
transition and the Cabibbo-Kobayashi-Maskawa matrix element
. Using recent lattice QCD calculations for the hadronic form
factors, we find using the BGL
parameterization, compatible with determinations from inclusive semileptonic
decays. We search for lepton flavor universality violation as a function of the
hadronic recoil parameter , and investigate the differences of the electron
and muon angular distributions. We find no deviation from Standard Model
expectations
Search for a doubly charged DDK bound state in Υ(1S, 2S) inclusive decays and via direct production in e⁺e⁻ collisions at √s = 10.520, 10.580, and 10.867 GeV
Search for a doubly charged DDK bound state in Υ(1S, 2S) inclusive decays and via direct production in e⁺e⁻ collisions at √s = 10.520, 10.580, and 10.867 GeV
We report the results of a first search for a doubly-charged bound state, denoted the , in and inclusive decays and via direct production in collisions at = 10.520, 10.580, and 10.867 GeV. The search uses data accumulated with the Belle detector at the KEKB asymmetric-energy collider. No significant signals are observed in the invariant-mass spectra of all studied modes. The 90\% credibility level upper limits on their product branching fractions in and inclusive decays ( anything), and the product values of Born cross section and branching fraction in collisions ( anything) at = 10.520, 10.580, and 10.867 GeV under different assumptions of masses varying from 4.13 to 4.17 GeV/, and widths varying from 0 to 5 MeV are obtained
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