286 research outputs found
Spin observables in the reaction
The T matrix of the LambdaN-> NN reaction, which is a strangeness changing
weak process, is derived. The explicit formulas of the spin observables are
given for s-wave p-Lambda final states which kinematically corresponds to
inverse reaction of the weak nonmesonic decay of Lambda hypernuclei. One can
study interferences between amplitudes of parity- conserving and violating,
spin- singlet and triplet and isospin- singlet and triplet. Most of them are
not available in the study of the nonmesonic decay. They clarify structure of
the reaction and constrain strongly theoretical models for weak hyperon nucleon
interaction.Comment: 7pages,ReVTeX,no figure
Nonmesonic Hyperon Weak Decay Spectra in C}
We study the nonmesonic weak decay (NMWD) of the
hypernucleus induced by the nucleon with
transition rate . The nuclear process is described by the interplay
of two models; one describing the NMWD of hyperon in the nuclear
environment, and the other taking into account the Final State Interaction
(FSI) of the two outgoing nucleons with the residual nucleus. The first one is
done in the framework of the Independent-Particle Shell-Model (IPSM), with the
decay dynamics represented by the exchange of
mesons with usual parametrization. For the second one is used a time dependent
multicollisional intranuclear cascade schema (implemented in the CRISP code -
Collaboration Rio-S\~ao Paulo). The results obtained for inclusive and
exclusive kinetic energy spectra, and the angular correlation are compared with
recent data from KEK and FINUDA experiments. The calculated ratio , between the numbers of emitted back-to-back
and pairs, is in good agreement with the experimental data.Comment: Proceedings of the International Nuclear Physics Conference 2010,
Vancouver, BC - Canada 4-9 Jul 201
First determination of the one-proton induced Non-Mesonic Weak Decay width of p-shell {\Lambda}-Hypernuclei
Previous studies of proton and neutron spectra from Non-Mesonic Weak Decay of
eight Lambda-Hypernuclei (A = 5-16) have been revisited. New values of the
ratio of the two-nucleon and the one-proton induced decay widths,
Gamma_2N/Gamma_p, are obtained from single proton spectra, Gamma_2N/Gamma_p =
0.50 +/- 0.24, and from neutron and proton coincidence spectra,
Gamma_2N/Gamma_p = 0.36 +/- 0.14stat +0.05sys -0.04sys , in full agreement with
previously published ones. With these values, a method is developed to extract
the one-proton induced decay width in units of the free Lambda decay width,
Gamma_p/Gamma_Lambda, without resorting to Intra Nuclear Cascade models but by
exploiting only experimental data, under the assumption of a linear dependence
on A of the Final State Interaction contribution. This is the first systematic
determination ever done and it agrees within the errors with recent theoretical
calculations.Comment: 16 pages, 3 figures, 2 table
Delayed clusters accompanying nonmesonic weak decay of the -hypernuclei: a clue to nonleptonic processes
The nonmesonic decay of -hypernuclei provides access to the
nonleptonic weak decay process , which is achievable only
through the observation of hypernuclear ground-state decays. We continue the
discussion of some specific cases which make it possible to detect a few
exclusive transitions, namely, the stripping of nucleon from the ground state
results in a resonance state decaying via emission of two clusters. Delayed
clusters accompanying weak decay of light hypernuclei give a unique information
on spin dependence of the weak decay matrix elements.Comment: Presented at International Bogolyubov Conference "Problems of
Theoretical and Mathematical Physics" (dedicated to the 100th anniversary of
the birth of N.N.~Bogolyubov) Dubna, Russia, August 21 - 27, 200
Photoproduction of Lambda(1405) and Sigma^{0}(1385) on the proton at E_\gamma = 1.5-2.4 GeV
Differential cross sections for and reactions have been measured in the photon energy range
from 1.5 to 2.4 GeV and the angular range of for the
scattering angle in the center-of-mass system. This data is the first
measurement of the photoproduction cross section. The
lineshapes of \LamS measured in and decay modes
were different with each other, indicating a strong interference of the isospin
0 and 1 terms of the scattering amplitudes. The ratios of \LamS
production to \SigS production were measured in two photon energy ranges: near
the production threshold ( GeV) and far from it ( GeV). The observed ratio decreased in the higher photon energy
region, which may suggest different production mechanisms and internal
structures for these hyperon resonances
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