Related papers: Eta --> 3 pi and quark masses
Using a low-background sample of $2.6\times 10^5$ $J/\psi\rightarrow\omega\eta(\omega\rightarrow\pi^{+}\pi^{-}\pi^{0},\eta\rightarrow\gamma\gamma)$ events, about 5 times larger statistics than previous experiments, we present a Dalitz plot…
Two types of pseudoscalar quarkonium electromagnetic decay processes, i.e. decay to a lepton pair, and to a lepton pair plus a photon (Dalitz decay), are analyzed at the leading order in NRQCD expansion. The former type of processes, highly…
Three body heavy meson decays allows one to extract important quantities for flavour physic, however the phenomenological analysis has some open problems to be solved in order to make possible to extract physical parameters with precision.…
The decay $\eta'\to\eta\pi^{0}\pi^{0}$ is studied in the framework of isobar model. It is shown, that good agreement with the experiment is achieved if $a_0$- and $\sigma$-meson contributions are taken into account. The contribution of…
The decays pi^0, eta, eta-prime -> gamma gamma are investigated up to next-to-next-to-leading order in the framework of the combined 1/N_c and chiral expansions. Without mixing of the pseudoscalar mesons the N_c independence of the pi^0 and…
We study the temperature dependence of the eta and eta' meson masses within the framework of U(3)_L x U(3)_R chiral perturbation theory, up to next-to-leading order in a simultaneous expansion in momenta, quark masses and number of colours.…
Based on a sample of (225.3\pm2.8)\times 10^{6} J/\psi events collected with the BESIII detector, the electromagnetic Dalitz decays of J/\psi \to P e^+e^-(P=\eta'/\eta/\pi^0) are studied. By reconstructing the pseudoscalar mesons in various…
The decays of eta_c to K^+K^-2(pi^+pi^-) and 3(pi^+pi^-) are observed for the first time using a sample of 5.8X10^7 J/\psi events collected by the BESII detector. The product branching fractions are determined to be B(J/\psi-->gamma…
In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pions was studied using…
We have observed new channels for $\tau$ decays with an $\eta$ in the final state. We study 3-prong tau decays, using the $\eta\to\gamma\gamma$ and $\eta\to 3\piz$ decay modes and 1-prong decays with two $\piz$'s using the…
The Dalitz decay eta -> e^+ e^- gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon tagging facility at the Mainz Microtron MAMI. The experimental…
A proposed solution of the anomalous behavior of the electron spectrum near the endpoint of tritium $\beta$-decay is offered. It is based on a new theory of mass in which mass becomes a dynamical variable, and the electron in the tritium…
We demonstrate a new likelihood method for extracting the top quark mass from events of the type ttbar-->bW(l+nu)bW(l+nu) This method estimates the top quark mass correctly from an ensemble of dilepton events. The method proposed by Dalitz…
Top quark studies at future $e^+e^-$ colliders are considered. Two issues are discussed: {a --}Some results are presented on the decays of top quarks. Energy distributions of charged leptons and neutrinos in $t\to bW\to be^+\nu$ and jets in…
The relation between the on-shell quark mass and the mass defined in the modified minimal subtraction scheme is computed up to order \alpha_s^3. Implications for the numerical values of the top and bottom quark masses are discussed. We show…
Instead of the glueball-$\eta'$ mixing ansatz, the latest measured ratios of the branching fractions of $B_{(s)}^0\to J/\psi \eta^{(\prime)}$ decays by LHCb can be understood by including the contribution from the light quark annihilation…
The decay $\eta'\rightarrow\pi^0\gamma\gamma$ is studied theoretically in the framework of the Vector Meson Dominance model (VMD). We find theoretically a significant contribution of the interference of $\omega-\rho$ and provide theoretical…
The decays $\omega/\phi \rightarrow 3\pi$ are considered in the dispersive framework that is based on the isobar decomposition and sub-energy unitarity. The inelastic contributions are parametrized by the power series in a suitably chosen…
The decays eta, eta-prime --> pi+ pi- l+ l- (with l = e, mu) are investigated within a chiral unitary approach which combines the chiral effective Lagrangian with a coupled-channels Bethe-Salpeter equation. Predictions for the decay widths…
Isospin violating hadronic decays of the \eta and \eta' mesons into 3\pi mesons are driven by a term in the QCD Lagrangian proportional to the mass difference of the d and u quarks. The source giving large yield of the mesons for such decay…