38 research outputs found
Search for Resonant Decays at Belle
We report measurements and searches for resonant decays where is a
meson or
the X(3872) particle.Comment: accepted by Physics Letters
Observation of the and the Y(2175) in
The cross sections for and e^+ e^- \to \phi
\fzero are measured from threshold to using
initial state radiation. The analysis is based on a data sample of 673
fb collected on and below the resonance with the Belle
detector at the KEKB asymmetric-energy collider. First measurements
are reported for the resonance parameters of the in the
mode: MeV/ and MeV/. A structure at ,
corresponding to the so called Y(2175), is observed; its mass and width are
determined to be MeV/ and , respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC
Search for \bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^- decay at Belle
We search for the doubly charmed baryonic decay
, in a data sample of
events accumulated at the resonance with the Belle
detector at the KEKB asymmetric e^+e^- collider. We find no significant signal
and set an upper limit of at 90%
confidence level. The result is significantly below a naive extrapolation from
assuming a simple Cabibbo-suppression
factor of . The small branching fraction could be attributed
to a suppression due to the large momentum of the baryonic decay products,
which has been observed in other charmed baryonic two-body B decays. trend
observed in other charmed baryonic two-body B decays.Comment: 12 page, 5 figures. Contribution paper for conferences EPS2007 and
Lepton Photon 2007, Belle-Conference-070
Search for B -> h(*) nu nubar Decays at Belle
We present a search for the rare decays B -> h(*) nu nubar, where h(*) stands
for a light meson. A data sample of 535 million BBbar pairs collected with the
Belle detector at the KEKB e+e- collider is used. Signal candidates are
required to have an accompanying B meson fully reconstructed in a hadronic mode
and signal-side particles consistent with a single h(*) meson. No significant
signal is observed and we set upper limits on the branching fractions at 90%
confidence level. The limits on B0 -> K*0 nu nubar and B+ -> K+ nu nubar decays
are more stringent than the previous constraints, while the first searches for
B0 -> K0 nu nubar, pi0 nu nubar, rho0 nu nubar, phi nu nubar and B+ -> K*+ nu
nubar, rho+ nu nubar are reported.Comment: 6 pages, 2 figures, submit to PR
A Low-Footprint Java-to-Native Compilation Scheme Using Formal Methods
Ahead-of-Time and Just-in-Time compilation are common ways to improve runtime performances of restrained systems like Java Card by turning critical Java methods into native code. However, native code is much bigger than Java bytecode, which severely limits or even forbids these practices for devices with memory constraints. In this paper, we describe and evaluate a method for reducing natively-compiled code by suppressing runtime exception check sites, which are emitted when compiling bytecodes that may potentially throw runtime exceptions. This is made possible by completing the Java program with JML annotations, and using a theorem prover in order to formally prove that the compiled methods never throw runtime exceptions. Runtime exception check sites can then safely be removed from the generated native code, as it is proved they will never be entered. We have experimented our approach on several card-range and embedded Java applications, and were able to remove almost all the exception check sites. Results show memory footprints for native code that are up to 70% smaller than the non-optimized version, and sometimes as low than 115% the size of the Java bytecode when compiled for ARM thumb
Measurement of cross sections of exclusive processes at GeV
The cross sections for the reactions have been measured using a data sample of 516
fb collected with the Belle detector at the KEKB asymmetric-energy
collider. The corresponding values of the cross sections are: fb , fb , fb and fb . The
energy dependence of the cross sections is presented using Belle measurements
together with those of CLEO and BaBar.Comment: 8 pages, 8 figure
Measurement of the Decay B_s^0 -> D_s^- pi^+ and Evidence for B_s^0 -> D_s^{+/-} K^{-/+} in e+e- Annihilation at sqrt(s)~10.87 GeV
We have studied Bs0 -> Ds- pi+ and Bs0 -> Ds^(-/+) K^(+/-) decays using 23.6
/fb of data collected at the Upsilon(5S) resonance with the Belle detector at
the KEKB e+e- collider.
This highly pure Bs0 -> Ds- pi+ sample is used to measure the branching
fraction, BR(Bs0 -> Ds- pi+)=[3.67 +0.35,-0.33}(stat.) +0.43,-0.42(syst.)
+-0.49(f_s)] x 10^{-3} (f_s=N(Bs(*) Bs(*)bar)/N(b\bar b)) and the fractions of
Bs0 event types at the Upsilon(5S) energy, {in particular N(Bs*
Bs*bar}/N(N(Bs(*) Bs(*)bar)=(90.1 +3.8,-4.0 +-0.2)%. We also determine the
masses M(Bs0)=(5364.4 +-1.3 +-0.7) MeV/c^2 and M(Bs*)=(5416.4 +-0.4 +-0.5)
MeV/c^2. In addition, we observe Bs0 -> Ds^(-/+) K^(+/-) decays with a
significance of 3.5\sigma and measure BR(Bs0 -> Ds^(-/+) K^(+/-))=[2.4
+1.2,-1.0(stat.) +-0.3(syst.) +-0.3(f_s)] x 10^{-4}.Comment: 5 pages, 4 figures, accepted by PR
Measurement of B(Ds -> munu)
We present a measurement of the branching fraction
using a 548 fb data sample collected by the Belle experiment at the KEKB
collider. The momentum is determined by reconstruction of the
system recoiling against in events of the type , where represents additional pions or photons
from fragmentation. The full reconstruction method provides high resolution in
the neutrino momentum and thus good background separation, equivalent to that
reached by experiments at the tau-charm factories. We obtain the branching
fraction , implying a decay constant of MeV.Comment: 6 pages, 2 figures, replaced by version subm. to Phys. Rev. Let
Search for
We report a search for the decay , using a sample of 657
pairs collected with the Belle detector at the
resonance. No statistically significant signal is found and an
upper limit for the branching fraction is determined to be at 90% confidence level.Comment: 5 pages, 2 figures, 3 tables, submitted to PRD(RC
Evidence for Neutral B Meson Decays to wK*0
We present the results of a study of the charmless vector-vector decay
B0->wK*0 with 657x10^6 BB(bar) pairs collected with the Belle detector at the
KEKB e+e- collider. We measure the branching fraction to be
B(B0->wK*0)=[1.8+/-0.7(stat)+/-0.3(syst)]x10^-6 with 3.0sigma significance. We
also perform a helicity analysis of the w and K*0 vector mesons, and obtain the
longitudinal polarization fraction
fL(B0->wK*0)=0.56+/-0.29(stat)+0.18-0.08(syst). Finally, we measure a large
non-resonant branching fraction B[B->wK+pi-; M(Kpi)\in(0.755,1.250)
GeV/c^2]=[5.1+/-0.7(stat)+/-0.7(syst)]x10^-6 with a significance of 9.5sigma.Comment: 6 pages, 3 figures (7 figure files