Related papers: Positronium-ion decay
In a recent publication [6], the Belle collaboration updated their analysis of the inclusive weak radiative B-meson decay, including the full dataset of (772 +_ 11) x 10^6 BBbar pairs. Their result for the branching ratio is now below the…
Germanium is a strong candidate as a laser source for silicon photonics. It is widely accepted that the band structure of germanium can be altered by tensile strain so as to reduce the energy difference between its direct and indirect band…
We shortly report on the two-photon decay width of the light $\sigma$-meson interpreted as a quarkonium state. Results are given in dependence on the $\sigma$-mass and the constituent mass of the light quark. The triangle quark-loop…
The processes $\psi(2S)\to \gamma \pi^+ \pi^-$, $\gamma K^+ K^-$ and $\gamma p \bar{p}$ have been studied using a sample of $3.7 \times 10^6$ produced $\psi(2S)$ decays. We determine the total width of the $\chi_{c0}$ to be…
We propose a direct method to calculate the decay width of a hadron decaying to two photons, which is conventionally obtained by an extrapolation for various off-shell form factors. The new method provides an simple way to examine the…
We calculate the relativistic corrections of relative order (Z alpha)^2$ to the two-photon decay rate of higher excited S and D states in ionic atomic systems, and we also evaluate the leading radiative corrections of relative order alpha…
Two-photon annihilation rates of $2^+$ tensor charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. Full Salpeter equation for $2^+$ tensor state is solved with a well defined…
Signal of the rare radiative decay PHI--->ETA+PI0+GAMMA was observed in the SND experiment at VEPP-2M electron-positron collider.The result is based on the analysis of data, corresponding to a total integrated luminosity of 4 pb^{-1}, or…
Motivated by concerns regarding possible two-body contributions to the recently-measured inclusive $\Upsilon$(nS)$\to\gamma+X$ direct photon spectrum, we report on a preliminary new study of exclusive radiative decays of the $\Upsilon$…
The effect of confinement on the self-annihilation rate of positronium is studied in three levels of approximation. Artificial restriction of the electron-positron separation leads to an increase in the annihilation rate over its vacuum…
Standards calculations by the Fermi's Golden rule involve approximations. These approximations could lead to deviations from the predictions of the standard model as discussed in another paper. In this paper we propose experimental searches…
Using $\gamma \gamma J/\psi, J/\psi \ra e^+ e^-$ and $\mu^+ \mu^-$ events from a sample of $14.0\times 10^6$ $\psip$ decays collected with the BESII detector, the branching fractions for $\psip\ra \pi^0\J$, $\eta\J$, and…
In living organisms the positron-electron annihilation (occurring during the PET imaging) proceeds in about 30% via creation of a metastable ortho-positronium atom. In the tissue, due to the pick-off and conversion processes, over 98% of…
Based on $2.7 \times 10^9~\psi(3686)$ decays collected with the BESIII detector, the radiative decay $\psi(3686)\to\gamma2(\pi^{+}\pi^{-})\eta$ is investigated to measure properties of S- and P-wave charmonium states. The branching fraction…
We consider indirect detection of meta-stable dark matter particles decaying into a stable neutral particle and a pair of standard model fermions. Due to the softer energy spectra from the three-body decay, such models could potentially…
This study appertains to the extraction of estimates for the masses and for the partial decay widths to pion-nucleon final states of the well-established (four-star) $s$ and $p$ baryon resonances below $2$ GeV. These estimates are…
The standard model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the $\beta$ decay of the free neutron. We report on the RDK II experiment which measured the photon…
In many calculations of the two--photon decay of hadronic molecules, the decay matrix element is estimated using the wave function at the origin prescription, in analogy to the two-photon decay of parapositronium. We question the…
We present analytic expressions to evaluate at O(alpha) the effects of soft-photon emission, and the related virtual corrections, in non-leptonic decays of the type B,D -> P1 P2, where P1 and P2 are scalar or pseudoscalar particles. The…
A two-neutron unbound excited state of $^{24}$O was populated through a (d,d') reaction at 83.4 MeV/nucleon. A state at $E = 715 \pm 110$ (stat) $\pm 45 $ (sys) keV with a width of $\Gamma < 2$ MeV was observed above the two-neutron…