41 research outputs found
Stacking Sequence Effect on the Fracture Behavior of Narrow L-Shaped Cross-Ply Laminates: Experimental Study
The stacking sequence effect of narrow L-shaped laminates on the fracture mode was studied.Изучено влияние последовательности упаковки узкого уголка из ламинатов на характер его разрушения
Low energy and dynamical properties of a single hole in the t-Jz model
We review in details a recently proposed technique to extract information
about dynamical correlation functions of many-body hamiltonians with a few
Lanczos iterations and without the limitation of finite size. We apply this
technique to understand the low energy properties and the dynamical spectral
weight of a simple model describing the motion of a single hole in a quantum
antiferromagnet: the model in two spatial dimension and for a double
chain lattice. The simplicity of the model allows us a well controlled
numerical solution, especially for the two chain case. Contrary to previous
approximations we have found that the single hole ground state in the infinite
system is continuously connected with the Nagaoka fully polarized state for
. Analogously we have obtained an accurate determination of the
dynamical spectral weight relevant for photoemission experiments. For
an argument is given that the spectral weight vanishes at the Nagaoka energy
faster than any power law, as supported also by a clear numerical evidence. It
is also shown that spin charge decoupling is an exact property for a single
hole in the Bethe lattice but does not apply to the more realistic lattices
where the hole can describe closed loop paths.Comment: RevTex 3.0, 40 pages + 16 Figures in one file self-extracting, to
appear in Phys. Rev
Exact spectra, spin susceptibilities and order parameter of the quantum Heisenberg antiferromagnet on the triangular lattice
Exact spectra of periodic samples are computed up to .
Evidence of an extensive set of low lying levels, lower than the softest
magnons, is exhibited.
These low lying quantum states are degenerated in the thermodynamic limit;
their symmetries and dynamics as well as their finite-size scaling are strong
arguments in favor of N\'eel order.
It is shown that the N\'eel order parameter agrees with first-order spin-wave
calculations. A simple explanation of the low energy dynamics is given as well
as the numerical determinations of the energies, order parameter and spin
susceptibilities of the studied samples. It is shown how suitable boundary
conditions, which do not frustrate N\'eel order, allow the study of samples
with spins.
A thorough study of these situations is done in parallel with the more
conventional case .Comment: 36 pages, REVTeX 3.0, 13 figures available upon request, LPTL
preprin
Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta
Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector,
the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are
measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and
(7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure
BESII Detector Simulation
A Monte Carlo program based on Geant3 has been developed for BESII detector
simulation. The organization of the program is outlined, and the digitization
procedure for simulating the response of various sub-detectors is described.
Comparisons with data show that the performance of the program is generally
satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM
Measurement of branching fractions for the inclusive Cabibbo-favored ~K*0(892) and Cabibbo-suppressed K*0(892) decays of neutral and charged D mesons
The branching fractions for the inclusive Cabibbo-favored ~K*0 and
Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample
of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with
the BES-II detector at the BEPC collider. The branching fractions for the
decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 ->
\~K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and
BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching
fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K*0X)
< 6.6%
Study of
New data are presented on from a sample of 58M
events in the upgraded BES II detector at the BEPC. There is a
conspicuous signal for and a peak at higher mass which
may be fitted with . From a combined analysis with
data, the branching ratio
is at the 95%
confidence level.Comment: 11 pages, 5 figures. Submitted to Phys. Lett.
Measurements of Cabibbo Suppressed Hadronic Decay Fractions of Charmed D0 and D+ Mesons
Using data collected with the BESII detector at storage ring
Beijing Electron Positron Collider, the measurements of relative branching
fractions for seven Cabibbo suppressed hadronic weak decays ,
, and , , and are presented.Comment: 11 pages, 5 figure
Direct Measurement of the Pseudoscalar Decay Constant fD+
The absolute branching fraction of has been directly
measured by an analysis of a data sample of about 33 collected
around GeV with the BES-II at the BEPC. At these energies,
meson is produced in pair as . A total of mesons are reconstructed from this data set. In the
recoil side of the tagged mesons, purely leptonic decay
events of are observed. This yields a branching fraction of
, and a
corresponding pseudoscalar decay constant
MeV.Comment: 7 pages, 8 figures, Submitted to Physics Letters B in October, 200