Related papers: New Results from the PIBETA Experiment
Recently, much work has been devoted to the calculation of order $\alpha$ corrections to the decay rate of pionium, the $\pi^+ \pi^-$ bound state. In previous calculations, nonrelativistic QED corrections were neglected since they start at…
The present status of double beta decay experiments are reviewed. The results of the most sensitive experiments, NEMO-3 and CUORICINO, are discussed. Proposals for future double beta decay experiments are considered. In these experiments…
The present status of double beta decay experiments (including the search for $2\beta^{+}$, EC$\beta^{+}$ and ECEC processes) are reviewed. The results of the most sensitive experiments are discussed. Average and recommended half-life…
We calculate the pion decay constant near the critical temperature of the $O(N)$ nonlinear sigma model in the large $N$ limit. Making use of the known low temperature behavior, we construct a Pad\'{e} approximant to obtain the behavior of…
PIONEER is a rapidly developing effort aimed to perform a pristine test of lepton flavour universality (LFU) and of the unitarity of the first row of the CKM matrix by significantly improving the measurements of rare decays of the charged…
Evaluated $2\beta^{-}(2\nu)$ half-lives and their systematics were reexamined in the framework of a phenomenological approach. Decay rate dependence on nuclear deformation, decay energy, shape coexistence, and forbidden transitions was…
We report results of proper-time evolution analyses of B decays at Belle, based on a 29.1/fb data sample recorded at the Upsilon (4S) resonance. These results include measurements of sin2phi_1, the lifetime of B-mesons, and the…
The recent neutrino oscillation experimental results indicate that at least one neutrino has a mass greater than 50 meV. The next generation of double-beta decay experiments will very likely have a sensitivity to an effective Majorana…
We report on recent results on the decay of the phi into pi^+ pi^- and phi radiative decays into pi^0 pi^0 gamma and pi^0 eta gamma, which require the consideration of the final state interaction of a pair of mesons in a region inaccessible…
Two mechanisms for the $\pi_1$ ($J^{PC}=1^{-+}$) hybrid meson decay processes $\pi_1\to\eta\pi,\eta'\pi$ are investigated. These mechanisms are applied to $\phi\to\eta\gamma,\eta'\gamma$ and $J/\psi\to\eta\gamma,\eta'\gamma$ decays to…
Fits of pion-nucleus potentials to large sets of pionic atom data reveal departures of parameter values from the corresponding free $\pi N$ parameters. These medium effects can be quantitatively reproduced by a chiral-motivated model where…
A new evaluation of 2beta-decay half lives and their systematics is presented. These data extend the previous evaluation and include the analysis of all recent measurements. The nuclear matrix elements for 2beta-decay transitions in 12…
A new partial wave analysis of pion photoproduction has been obtained in the framework of fixed-t dispersion relations valid form threshold up to 500 MeV. It is based on new Mainz data for \pi^{0} and \pi^{+} production off the proton and…
Pionium lifetime corrections are evaluated in the frameworks of constrained Bethe-Salpeter equation and chiral perturbation theory. Corrections of order $O(\alpha)$ are calculated with respect to the conventional lowest-order formula, in…
Using a sample of $4.48\times10^{8}$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII collider, we study the two-photon decays of the pseudoscalar mesons $\pi^0$, $\eta$, $\eta^\prime$, $\eta(1405)$, $\eta(1475)$,…
We re-investigate the impact of isospin violation for extracting the s-wave pion pion scattering phase shift difference delta_0(M_K) - delta_2(M_K) from K -> pi pi decays. Compared to our previous analysis in 2003, more precise experimental…
We study the radiative $\rho$, $\omega$ and $\phi$ decay into $\pi^0 \pi^0 \gamma$ and $\pi^0 \eta \gamma $ taking into account mechanisms in which there are two sequential vector-vector-pseudoscalar or axial-vector--vector--pseudoscalar…
The weak decay of the kaon to two pions is studied within the NJL Model. Using the standard effective weak Hamiltonian, both the decay amplitude arising from an intermediate state \sigma-meson and the direct decay amplitude are calculated.…
We explore the possibility of studying $B\to\pi l\nu$ semileptonic decays at large recoil momentum. Our methods include the use of a random-wall source for the pion to reduce statistical errors, and different smearing functions are used for…
A prediction for the contributions of chiral loops and the L$\sigma$M model to the radiative $\phi\to\pi^0\eta\gamma$ decay mode is presented. The L$\sigma$M is used as an appropriate framework for describing the pole effects of the…