252 research outputs found
Forward K+ production in subthreshold pA collisions at 1.0 GeV
K+ meson production in pA (A = C, Cu, Au) collisions has been studied using
the ANKE spectrometer at an internal target position of the COSY-Juelich
accelerator. The complete momentum spectrum of kaons emitted at forward angles,
theta < 12 degrees, has been measured for a beam energy of T(p)=1.0 GeV, far
below the free NN threshold of 1.58 GeV. The spectrum does not follow a thermal
distribution at low kaon momenta and the larger momenta reflect a high degree
of collectivity in the target nucleus.Comment: 4 pages, 3 figure
Search for the decay at Belle
We report a search for the rare charmless decay
using a data sample of
pairs collected at the resonance with
the Belle detector at the KEKB asymmetric-energy collider. No
statistically significant signal is found and a 90% confidence-level upper
limit is set on the decay branching fraction as .Comment: 8 pages, 3 figures, submitted to PRD(RC
Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV
We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and
B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B
B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible
cross sections for the three-body production of sigma_vis(e+e- => [B
B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- =>
[B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper
limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a
121.4 1/fb data sample collected with the Belle detector at a center-of-mass
energy near the Y(5S) peak.Comment: 8 pages, 2 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.
Search for and a measurement of the branching fraction for
We search for the decay and measure the
branching fraction for using
121.4~ of data collected at the
resonance with the Belle detector at the KEKB asymmetric-energy
collider. The branching fraction is measured
to be , where is the fraction of
in events. Our result is in good
agreement with the theoretical predictions as well as with a recent measurement
from LHCb. We observe no statistically significant signal for the decay
and set a confidence-level upper
limit on its branching fraction at . This constitutes a
significant improvement over the previous result.Comment: 6 pages, 3 figure
Search for a massive invisible particle in and decays
We present a search for a non-Standard-Model invisible particle in the
mass range in and
decays. The results are obtained from a data sample that corresponds to pairs,
collected at the resonance with the Belle detector at the KEKB
collider. One meson is fully reconstructed in a hadronic mode to
determine the momentum of the lepton of the signal decay in the rest frame of
the recoiling partner meson. We find no evidence of a signal and set upper
limits on the order of .Comment: 8 pages, 4 figures, 3 table
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 the K- -> pi0 e- nu decay
The decay K- -> pi0 e- nu has been studied using in-flight decays detected
with "ISTRA+" setup operating at the 25 GeV negative secondary beam of the U-70
PS. About 130K events were used for the analysis. The lambda_+ parameter of the
vector formfactor has been measured: lambda_+ = 0.0293 +- 0.0015(stat) +-
0.002(syst).
The limits on the possible tensor and scalar couplings have been derived:
f_T/f_+(0)=-0.044 +0.059 -0.057 (stat) f_S/f_+(0)=-0.020 +0.025 -0.016 (stat)Comment: 11 pages, Latex, 9 picture
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
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
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