807 research outputs found
Material Selection of Z-fibre in Stitched Composites - Experimental and Analytical Comparison Approach
Strain energy release rates are measured and compared for laminated composites stitched with different fibre materials – Carbon, Kevlar and Vectran. DCB test and FE simulation are performed to evaluate the interlaminar toughness. It is proven that Vectran provides the toughest interlaminar reinforcement and is most suitable for Zfibre application
Search for leptonic decays of D0 mesons
We search for the flavor-changing neutral current decays D0\to mu+mu- and
D0\to e+e-, and for the lepton-flavor violating decays D0\to e\pm mu\mp using
660 fb^-1 of data collected with the Belle detector at the KEKB
asymmetric-energy e+e- collider. We find no evidence for any of these decays.
We obtain significantly improved upper limits on the branching fractions:
B(D0\to mu+mu-)<1.4x10-7, B(D0\to e+e-)<7.9x10-8, and B(D0\to e+mu-)+B(D0\to
mu+e-)<2.6x10-7 at 90% confidence level.Comment: 6 pages, 3 figure
Search for CP violation in tau -> K^0_S pi nu_tau decays at Belle
We report on a search for CP violation in tau -> K^0_S pi nu_tau decays using
a data sample of 699 fb^{-1} collected in the Belle experiment at the KEKB
electron-positron asymmetric-energy collider. The CP asymmetry is measured in
four bins of the invariant mass of the K^0_S pi system and found to be
compatible with zero with a precision of O(10^{-3}) in each mass bin. Limits
for the CP violation parameter Im(eta_S) are given at a 90 % confidence level.
These limits are |Im(eta_S)|<0.026 or better, depending on the parameterization
used to describe the hadronic form factors and improve upon previous limits by
one order of magnitude
Search for CP violation in the decays and
We have searched for CP violation in the charmed meson decays and using 673 fb of data
collected with the Belle detector at the KEKB asymmetric-energy
collider. No evidence for CP violation is observed. We report the most
sensitive CP asymmetry measurements to date for these decays: , , , and , where the first uncertainties are statistical and
the second are systematic
Precision measurement of charged pion and kaon differential cross sections in electron-positron annihilation at Q = 10.52 GeV
Measurements of inclusive differential cross sections for charged pion and
kaon production in electron-positron annihilation have been carried out at a
center-of-mass energy of Q = 10.52 GeV. The measurements were performed with
the Belle detector at the KEKB electron-positron collider using a data sample
containing 113 million e+e- -> qqbar events, where q={u,d,s,c}. We present
charge-integrated differential cross sections d\sigma_h+-/dz for h+- = pi+-,
K+- as a function of the relative hadron energy z = 2*E_h / sqrt{s} from 0.2 to
0.98. The combined statistical and systematic uncertainties for pi+- (K+-) are
4% (4%) at z ~ 0.6 and 15% (24%) at z ~ 0.9. The cross sections are the first
measurements of the z-dependence of pion and kaon production for z > 0.7 as
well as the first precision cross section measurements at a center-of-mass
energy far below the Z^0 resonance used by the experiments at LEP and SLC.Comment: 7 pages, 3 figures. Ancillary file including all cross section and
uncertainty values with 10 pages, 5 figure
Evidence for direct CP violation in the decay B->D(*)K, D->KsPi+Pi- and measurement of the CKM phase phi3
We present a new measurement of the unitarity triangle angle phi3 using a
Dalitz plot analysis of the KsPi+Pi- decay of the neutral D meson produced in
B->D(*)K decays. The method exploits the interference between D0 and D0bar to
extract the angle phi3, strong phase delta and the ratio r of suppressed and
allowed amplitudes. We apply this method to a 605 fb-1 data sample collected by
the Belle experiment. The analysis uses three decays: B->DK, and B->D*K with
D*->DPi0 and D*->Dgamma, as well as the corresponding charge-conjugate modes.
From a combined maximum likelihood fit to the three modes, we obtain phi3 =
78.4^+10.8_-11.6 +- 3.6 (syst) +- 8.9 (model) degrees. CP conservation in this
process is ruled out at the confidence level (1-CL)=5x10^-4, or 3.5 standard
deviations.Comment: 10 pages, 5 figures, 4 tables. Replaced by version published in Phys.
Rev.
Measurements of Branching Fractions and Time-dependent CP Violating Asymmetries in Decays
We report measurements of branching fractions and time-dependent CP
asymmetries in and decays
using a data sample that contains pairs
collected at the resonance with the Belle detector at the KEKB
asymmetric-energy collider. We determine the branching fractions to
be
and . We measure CP asymmetry parameters and in and , ,
, and in , where the first uncertainty is
statistical and the second is systematic. We exclude the conservation of CP
symmetry in both decays at equal to or greater than significance.Comment: 7 pages, 2 figure
Search for double charmonium decays of the P-wave spin-triplet bottomonium states
Using a sample of 158 million events collected with the Belle
detector, we search for the first time for double charmonium decays of the
-wave spin-triplet bottomonium states (,
\chi_{bJ} \to \jpsi \jpsi, \jpsi \psp, \psp \psp for J=0, 1, and 2). No
significant signal is observed in the double charmonium mass
spectra, and we obtain the following upper limits, \BR(\chi_{bJ} \to \jpsi
\jpsi)<7.1\times 10^{-5}, , ,
\BR(\chi_{bJ} \to \jpsi \psp)<1.2\times 10^{-4}, ,
, \BR(\chi_{bJ} \to \psp \psp)<3.1\times 10^{-5},
, for J=0, 1, and 2, respectively, at
the 90% confidence level. These limits are significantly lower than the central
values (with uncertainties of 50% to 70%) predicted using the light cone
formalism but are consistent with calculations using the NRQCD factorization
approach.Comment: 7 pages, 4 figures, 1 tabl
Measurement of the decay and determination of
We present a measurement of the charmless semileptonic decay
using a data sample containing 657
events collected with the Belle detector at the KEKB
asymmetric-energy collider operating near the
resonance. We determine the total branching fraction of the decay,
. We also report a new precise measurement
of the differential decay rate, and extract the Cabibbo-Kobayashi-Maskawa
matrix element using model-independent and -dependent approaches.
From a simultaneous fit to the measured differential decay rate and lattice QCD
results, we obtain , where the error
includes both statistical and systematic uncertainties.Comment: 8 pages, 3 figures, Submitted to PRD(RC
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