Related papers: Pionium in the elementary particle decays
We study the three-pion decays of the lightest isoscalar vector mesons, omega and phi, in a dispersive framework that allows for a consistent description of final-state interactions between all three pions. Our results are solely dependent…
We performed the first direct calculation of the probability of pionium (pi+pi- atom) ionization in the target. The dependence of the probability of pionium ionization in the target as a function of the pionium lifetime is established.…
Rare radiative decay $\phi\to\eta\pi^0\gamma$ was studied with SND detector at {VEPP-2M} electron-positron collider and its branching ratio was measured: $B(\phi\to\eta\pi^0\gamma)=(0.88\pm0.14\pm0.09)\cdot 10^{-4}$. Significant…
The decay modes and fractions in particle physics are some quantitative and very complex questions. Various decays of particles and some known decay formulas are discussed. Many important decays of particles and some known decays of…
The rates and spectra of the anomalous $\eta\to\pi^+\pi^-\gamma$ and $\eta' \to\pi^+\pi^-\gamma$ decays are calculated. The approach is based on the effective meson Lagrangian obtained in the Nambu-Jona-Lasinio model with vector and…
We complement studies of the neutral pion transition form factor pi^0 --> gamma^(*) gamma^(*) with calculations for the electromagnetic decay widths of the processes pi^0 --> e^+ e^-, pi^0 --> e^+ e^- gamma and pi^0 --> e^+ e^- e^+ e^-.…
The decays $K \to \pi l^{+} l^{-}$, $K \to \pi \gamma \gamma $ and $K \to \pi \nu {\bar \nu}$ are investigated using the higher order terms of the chiral perturbation theory. The counterterms induced by strong, weak and electromagnetic…
Pion emitting decays and radiative ones of D^{*+,0} and D_s^{*+} are studied. As the result, the full-width of D^{*0} is predicted, by assuming the isospin symmetry. In addition, the isospin non-conserving D_s^{*+} --> D_s^+ pi^0 decay is…
The consistent matching of short-distance contributions and hadronic matrix elements is crucial for precise predictions of weak processes involving hadrons. In this Letter, we address this point for charged-current processes involving two…
We report on analyses of $B^-$ mesons decaying into $D^{*+}\pi^-\pi^-$ and $D^+\pi^-\pi^-$ final states using 89 million $B^-$ decays collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory. Preliminary measurements are…
Based on the isospin dependent transport model IBUU, the pion production and its absorption are thoroughly studied in the central collision of $Au+Au$ at a beam energy of 400 MeV/nucleon. It is found that the pions are firstly produced by…
The $J/\Psi$ decay into a baryon pair and a pseudoscalar meson is computed, for some channels, in lowest order in perturbative QCD, modeling the baryon with a quark-diquark system. We use a set of parameters that has been proposed by some…
Order \alpha^2 corrections to the decay rate of orthopositronium are calculated in the framework of nonrelativistic QED. The resulting contribution is found to be in significant disagreement with one set of experimental measurements though…
Mesonic baryon resonance decays are calculated from constituent quark models along a Poincar\'e-invariant generalization of the elementary emission model. Covariant results of pionic decay widths are presented for the…
Two results from the PIENU Experiment are presented reporting a test of lepton universality in pion decay and improved limits on heavy neutrinos coupling to positrons. The status of the full analysis for the $\pi^+ \rightarrow \mbox{e}^+…
Mechanism of di-pion transitions $nS\to n'S\pi\pi(n=3,2; n'=2,1)$ in bottomonium and charmonium is studied with the use of the chiral string-breaking Lagrangian allowing for the emission of any number of $\pi(K,\eta),$ and not containing…
Medium modifications of the pion-omega-rho vertex are analyzed in context of the omega -> pi gamma* and rho -> pi gamma* decays in nuclear matter. A relativistic hadronic model with mesons, nucleons, and Delta(1232)isobars is applied. A…
The theoretical calculation for pseudo--scalars hadronic decays $K \to \pi a$ is reviewed. %with the Axion-Like-Particle escaping the detection, While one-loop penguin contributions are usually considered, tree-level processes have most…
We consider the transitions from the $Z_b(10610)$ and $Z_b(10650)$ resonances to the states of bottomonium with emission of a pion. The $Z_b$ resonances are viewed as `molecular' objects of a large spatial size made of heavy $B^{(*)}$…
We give the detailed analyses for the gluonic-penguin effect on the $\kp$ and $\pp$ decays of the $B$ meson. In the standard model, it is shown that the ratio $BR(B\A\kp)/BR(B\A\pp)$ takes the value $0.5\sim 3.0$ with the strongly depending…