Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAnalysis of the nonleptonic two-body decays of the $Lambda$~hyperon
70
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We systematically study two-body nonleptonic decays of light lambda hyperon $Lambda to p pi^- (npi^0)$ 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 an intermediate $frac12^+$ and $frac12^-$ baryon resonances. The contributions from $frac12^+$ resonances are calculated straightforwardly by account for nucleon and $Sigma$ baryons whereas the contributions from $frac12^+$ resonances are calculated by using the well-known soft-pion theorem in the current-algebra approach. It allows to express the parity-violating S-wave amplitude in terms of parity-conserving matrix elements. From our previous analysis of heavy baryons we know that short distance effects induced by internal topologies are not suppressed in comparison with external $W$-exchange diagram and must be included for description of data. Here, in the case of $Lambda$ decays we found that the contribution of external and internal $W$-exchange diagrams is sizably suppressed, e.g., by one order of magnitude in comparison with data, which are known with quite good accuracy. The major role to get consistency with experiment play pole diagrams.
rate research
Read More
A sensitive search for the rare decays Omega^- to Lambda pi^- and Xi^0 to p pi^- has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |Delta S| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. We obtain the branching-fraction limits B(Omega^- to Lambda pi^-)< 2.9 x 10^{-6} and B(Xi^0 to p pi^-)< 8.2 x 10^{-6}, both at 90% confidence level.
Many decays of light baryons consisting of light $u,d,s$ quarks have been measured, and these measurements will help us to understand the decay properties of light baryons. In this work, we study two-body nonleptonic weak decays of light baryon octet $(T_8)$ and baryon decuplet $(T_{10})$ by the topological diagram approach (TDA) under the SU(3) flavor symmetry for the first time. We find that (1) the TDA and the SU(3) irreducible representation approach (IRA) match consistently in $T_{10}to T^{()}_{8,10}P_8$ ($P_8$ is the light pseudoscalar meson octet); (2) almost all relevant not-yet-measured $mathcal{B}(T_{10}to T_8 P_8)$ may be predicted by using three experimental data of $mathcal{B}(Omega^-to Xi^0pi^-,Xi^-pi^0,Lambda^0K^-)$, and the upper limits of $mathcal{B}(T_{10}to T{}_{10}pi^-)$ may be obtained from the experimental upper limit of $mathcal{B}(Omega^-to Xi^{*0}pi^-)$ by both the TDA and the IRA together, nevertheless, all new predicted branching ratios are too small to br reached in current experiments; (3) $T_8to T_8 P_8$ decays are quite complex in terms of the TDA, and we find that W-exchange diagrams give large and even dominant contributions by using relevant experimental data and the isospin relations.
We analyze $D to P V$, $D to PP$ and $D to VV$ decays within a model developed to describe the semileptonic decays $D to V l u_l$ and $Dto P l u_l$. This model combines the heavy quark effective Lagrangian and chiral perturbation theory. We determine amplitudes for decays in which the direct weak annihilation of the initial $D$ meson is absent or negligible, and in which the final state interactions are small. This analysis reduces the arbitrariness in the choice of model parameters. The calculated decay widths are in good agreement with the experimental results.
We calculate the semileptonic and a subclass of sixteen nonleptonic two-body decays of the double charm baryon ground states $Xi_{cc}^{++},,Xi_{cc}^{+}$ and $Omega_{cc}^+$ where we concentrate on the nonleptonic decay modes. We identify those nonleptonic decay channels in which the decay proceeds solely via the factorizing contribution precluding a contamination from $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the various helicity amplitudes which describe the dynamics of the $1/2^+ to 1/2^+$ and $1/2^+ to 3/2^+$ transitions induced by the Cabibbo favored effective $(c to s)$ and $(d to u)$ currents. We then proceed to calculate the rates of the decays as well as polarization effects and angular decay distributions of the prominent decay chains resulting from the nonleptonic decays of the double heavy charm baryon parent states.
We analyze charm meson semileptonic $D to V l u_l$ and $Dto P l u_l$ and nonleptonic $D to P V$, $D to PP$ and $D to VV$ decays within a model which combines the heavy quark effective Lagrangian and chiral perturbation theory.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
