The excitation curve for the τ τ− production in electron positron annihilation near the threshold is revisited with the aim of updating and extending a previous work. We find that the corrections of the relative magnitude O(α) near the threshold are significantly contributed by the radiative modification of the Coulomb interaction between the τ leptons. The interpolation between the Coulomb eff...

The radiative B → τ + τ − γ decay is investigated in the framework of the Standard Model. When only short (short and long together) distance contributions are taken into account, the Branching Ratio is found as 9.54 × 10 −9 (1.52 × 10 −8), for the value of the cut δ = 0.01 imposed on the photon energy.

We study lifetimes of heavy mesons in the 't Hooft model, a large-Nc theory strong interaction two-dimensional spacetime. Since this model is solvable, one can evaluate total decay widths through hadronic amplitudes that are determined unambiguously within formalism. investigate quark-hadron duality by numerically comparing exclusive result and from quark expansion, with contribution Pauli inte...

In this paper, we investigate the stability of equilibrium in stage-structured and density-dependent predator–prey system with Beddington–DeAngelis functional response. First, by checking sign real part for eigenvalue, local origin boundary are studied. Second, explore positive τ=0 τ≠0 (time delay τ is time taken from immaturity to maturity predator), which shows that dependent on parameter τ. ...