相关论文: Subthreshold poles in electron-positron annihilati…
Quantities like the fine structure constant at the pole of the Z boson and the anomalous magnetic moment of the muon are of profound importance for testing the Standard Model of elementary particle physics. Because these quantities are…
The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2M collider in the energy region $\sqrt[]{s}$ below 980 MeV. This measurement was based on about $1.2…
The hyperbolic version of Roy-Steiner equation describing low energy $\pi N$ scatterings, with larger analyticity domain in the complex $s$ plane is solved. The numerical results on phase shifts of low partial waves are in agreement with…
Using the CLEO-c detector, we have measured the charm hadronic cross sections for $e^{+}e^{-}$ annihilations at a total of thirteen center-of-mass energies between 3.97 and 4.26 GeV. Observed cross sections for the production of $D\bar{D}$,…
A brief review is given of recent positron studies of metal and semiconductor nanocrystals. The prospects offered by positron annihilation as a sensitive method to access nanocrystal (NC) properties are described and compared with other…
We present the results of lifetime positron annihilation spectroscopy (PALS) for the alloys Fe21Ga and Fe22.4Ga, whose defect structure is connected with annealing from 20 to 1000C along the phase diagram of Fe21Ga and Fe22.4Ga, at the…
The electron positron annihilation reaction into four pion production has been studied, through the channel $e^++e^-\to \bar \rho+\rho $. The differential (and total) cross sections and various polarization observables for this reaction…
We argue that the free electron and positron can be considered as different, independent particles, each of which is characterized by the complete set of the Dirac plane waves. This completely symmetric representation of the particles makes…
We establish a comprehensive theoretical framework for the electron-positron single-inclusive annihilation (SIA) process that incorporates higher-twist contributions up to twist-4 and demonstrate that these effects should be considered in…
The cross section values of $J/\psi\ \eta_c$ and $J/\psi\ J/\psi$ production in $e^+e^-$ annihilation are estimated within one-loop approximation near $Z$ pole, as well as at higher energies. Both intermediate bosons, $\gamma$ and $Z$, are…
A small difference between the energy of the para-positronium (p-Ps) and ortho-positronium (o-Ps) states suggests the possibility of superposition of p-Ps and o-Ps during the formation of positronium (Ps) from pre-Ps terminating its…
Semi-annihilation is a generic feature of particle dark matter that is most easily probed by cosmic ray experiments. We explore models where the semi-annihilation cross section is enhanced at late times and low temperatures by the presence…
The absence of observed charmonium-like states with the exotic quantum numbers $J^{PC}=1^{-+}$ has prompted us to investigate the production rates of the $1^{-+}$ $D\bar D_1(2420)$ and $D^*\bar D_1(2420)$ hadronic molecules, which we refer…
Using 3.08 million psi(2S) decays observed in e^+e^- collisions by the CLEO detector, we present the results of a study of the psi(2S) decaying into baryon-antibaryon final states. We report the most precise measurements of the following…
A selection of results from electron-positron collisions at BESIII are reviewed. The results presented here illustrate the wide range of physics topics that can be studied using the Beijing Electron Positron Collider~(BEPC). At low…
Based on $e^+e^-$ annihilation data samples collected with the BESIII detector at the BEPCII collider at 13 center of mass energies from 4.008 to 4.600 GeV, measurements of the Born cross section of $e^{+}e^{-}\rightarrow p \bar{p} \pi^{0}$…
The influence of the spin-dependent phase shifts (SDPS) associated to the electronic reflection and transmission amplitudes acquired by electrons upon scattering on the potential barrier on the Andreev reflection probability of electron and…
We report new measurements of the branching fraction $\cal B(D_s^+\to \ell^+\nu)$, where $\ell^+$ is either $\mu^+$ or $\tau^+(\to\pi^+\bar{\nu}_\tau)$, based on $6.32$ fb$^{-1}$ of electron-positron annihilation data collected by the…
Using e+e- -> Ds^-Ds^{*+} and Ds^{*-}Ds^+ interactions at 4170 MeV collected with the CLEO-c detector, we investigate the semileptonic decays Ds+ -> f0(980) e+ nu, and Ds+ -> phi e+ nu. By examining the decay rates as functions of the…
A high-precision determination of the main parameters of the \psi(2S) resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-} collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the energy…