753 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
Search for and branching fraction measurement of
We have searched for the Cabibbo-suppressed decay
in collisions using a data sample corresponding to an integrated
luminosity of 915 . The data were collected by the Belle
experiment at the KEKB asymmetric-energy collider running at or near
the and resonances. No significant signal is
observed, and we set an upper limit on the branching fraction of
at 90% confidence
level. The contribution for nonresonant decays
is found to be consistent with zero and the corresponding upper limit on its
branching fraction is set to be at 90% confidence level. We also measure the branching
fraction for the Cabibbo-favored decay ; the
result is , which is
the most precise measurement to date. Finally, we have searched for an
intermediate hidden-strangeness pentaquark decay . We see no
evidence for this intermediate decay and set an upper limit on the product
branching fraction of at 90% confidence level.Comment: 8 pages, 5 figures, 1 table, minor text change in version
Measurements of the and resonances via
We report new measurements of the total cross sections for ( = 1, 2, 3) and from a
high-luminosity fine scan of the region - GeV with the
Belle detector. We observe that the spectra have
little or no non-resonant component and extract from them the masses and widths
of and and their relative phase. We find
MeV/ and
\Gamma_{10860}=(53.7^{+7.1}_{-5.6}\,^{+1.3}_{-5.4}) MeV and report first
measurements M_{11020}=(10987.5^{+6.4}_{-2.5}\,^{+9.0}_{-2.1}) MeV/,
\Gamma_{11020}=(61^{+9}_{-19}\,^{+2}_{-20}) MeV, and \phi_{\rm
11020}-\phi_{\rm 10860} = (-1.0\pm0.4\,^{+1.4}_{-0.1}) rad.Comment: University of Cincinnati preprint UCHEP-15-01, submitted to Physical
Review D - Rapid Communication
Observation of and search for violation in radiative charm decays
We report the first observation of the radiative charm decay and the first search for violation in decays , , and , using a data sample of
943 fb collected with the Belle detector at the KEKB asymmetric-energy
collider. The branching fraction is measured to be , where the first
uncertainty is statistical and the second is systematic. The obtained
asymmetries, , , and
, are consistent with no violation. We also present an improved
measurement of the branching fractions and
Observation of a new charged charmoniumlike state in B -> J/psi K pi decays
We present the results of an amplitude analysis of anti-B0 -> J/psi K- pi+
decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/psi pi+ is
observed with a significance of 6.2 sigma. The mass and width of the Zc(4200)+
are 4196 +31-29 +17-13 MeV/c^2 and 370 +70-70 +70-132 MeV, respectively; the
preferred assignment of the quantum numbers is J^P = 1^+. In addition, we find
evidence for Zc(4430)+ -> J/psi pi+. The analysis is based on a 711 fb^-1 data
sample collected by the Belle detector at the asymmetric-energy e+ e- collider
KEKB.Comment: 14 pages, 13 figure
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.
First observation of the hadronic transition and new measurement of the and parameters
Using a sample of decays collected by
the Belle experiment at the KEKB collider, we observe for the first
time the transition with the branching fraction
and we measure the mass MeV/, corresponding to the hyperfine splitting MeV/. Using the transition , we measure the mass MeV/, corresponding to MeV/, the width
MeV/ and the branching
fraction .Comment: 7 pages, 2 figures, submitted to Phys. Rev. Let
Inclusive cross sections for pairs of identified light charged hadrons and for single protons in at 10.58 GeV
We report the first double differential cross sections of two charged pions
and kaons () in electron-positron annihilation as a
function of the fractional energies of the two hadrons for any charge and
hadron combination. The dependence of these di-hadron cross sections on the
topology (same, opposite-hemisphere or anywhere) is also studied with the help
of the event shape variable thrust and its axis. The ratios of these di-hadron
cross sections for different charges and hadron combinations directly shed
light on the contributing fragmentation functions. For example, we find that
the ratio of same-sign pion pairs over opposite-sign pion pairs drops toward
higher fractional energies where disfavored fragmentation is expected to be
suppressed. These di-hadron results are obtained from a
data sample collected near the resonance with the Belle detector
at the KEKB asymmetric-energy collider. Extending the previously
published single-pion and single-kaon cross sections, single-proton () cross sections are extracted from a data
sub-sample.Comment: submitted to PR
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
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