82 research outputs found
Measurement of via initial state radiation at Belle
The process (=1, 2) is studied via initial
state radiation using 980 fb of data at and around the
(=1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB
asymmetric-energy collider. No significant signal is observed except
from decays. Upper limits on the cross sections between
and are determined at the 90% credibility
level, which range from few pb to a few tens of pb. We also set upper limits on
the decay rate of the vector charmonium [), , and
] and charmoniumlike [, , and ] states
to .Comment: Accepted by PR
Studies of charmed strange baryons in the final state at Belle
We report the discovery of , observed by its decay into
the final state , and present the first observation and evidence
of the decays of and into .
We also perform a combined analysis of the with the
and decay modes to measure
the ratios of branching fractions, masses and widths with improved accuracy. We
measure the ratios of branching fractions , , and , where the uncertainties are
statistical and systematic. The analysis is performed using a 980 fb
data sample collected with the Belle detector at the KEKB asymmetric-energy
collider.Comment: Submitted to PR
Study of pair production in single-tag two-photon collisions
We report a measurement of the differential cross section of pair
production in single-tag two-photon collisions, , in scattering. The cross section is measured for up to
30 GeV, where is the negative of the invariant mass squared of the
tagged photon, in the kinematic range 0.5 GeV < W < 2.1 GeV and < 1.0 for the total energy and pion scattering angle, respectively,
in the center-of-mass system. The results are based on a data
sample of 759 fb collected with the Belle detector at the KEKB
asymmetric-energy collider. The transition form factor of the
and that of the with the helicity-0, -1, and -2
components separately are measured for the first time and are compared with
theoretical calculations.Comment: 36 pages, 37 figures, 11 tables, Belle Preprint 2015-15, KEK Preprint
2015-2
Observation of
We report the first observation of the decays . The data sample of fb used in this analysis corresponds
to million pairs, collected at the resonance by
the Belle detector at the KEKB asymmetric-energy collider. We
observe and excesses of events for the two decay
modes and measure the branching fractions of and to be
and ,
respectively, where the first uncertainties are statistical and the second are
systematic. These results are not compatible with the predictions based on the
generalized factorization approach. In addition, a threshold enhancement in the
di-baryon () system is observed, consistent with that observed
in similar decays.Comment: 16 pages, 3 figures and 3 tables, submitted to 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 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
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.
Observation of Mixing in Collisions
We observe mixing in the decay
using a data sample of integrated luminosity 976 fb collected with the
Belle detector at the KEKB asymmetric-energy collider. We measure the
mixing parameters and and the ratio of doubly Cabibbo-suppressed to
Cabibbo-favored decay rates , where the
uncertainties are statistical and systematic combined. Our measurement excludes
the no-mixing hypothesis at the 5.1 standard deviation level.Comment: 6 pages, 4 figure
- …