Search results for "гипероны"
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Hyperon forward spin polarizability gamma0 in baryon chiral perturbation theory
2015
We present the calculation of the hyperon forward spin polarizability gamma0 using manifestly Lorentz covariant baryon chiral perturbation theory including the intermediate contribution of the spin 3/2 states. As at the considered order the extraction of gamma0 is a pure prediction of chiral perturbation theory, the obtained values are a good test for this theory. After including explicitly the decuplet states, our SU(2) results have a very good agreement with the experimental data and we extend our framework to SU(3) to give predictions to the hyperons' gamma0 values. Prominent are the Sigma^- and Xi^- baryons as their photon transition to the decuplet is forbidden in SU(3) symmetry and th…
Analysis of the nonleptonic two-body decays of the Λ hyperon
2021
We systematically study two-body nonleptonic decays of light lambda hyperon $\Lambda \to p \pi^- (n\pi^0)$ with account for both short- and long-distance effects. The short-distance effects are induced by five topologies of external and internal weak $W^\pm$ exchange, while long-distance effects are saturated by an inclusion of the so-called pole diagrams with intermediate $\frac{1}{2}^+$ and $\frac{1}{2}^-$ baryon resonances. The contributions from $\frac12^+$ resonances are calculated straightforwardly by account for nucleon and $\Sigma$ baryons whereas the contributions from $\frac{1}{2}^-$ resonances are calculated by using the well-known soft-pion theorem in the current-algebra approac…