Related papers: The $\eta^\prime$ transition form factor from spac…

We report the first measurement of the di-electron invariant mass dependent transition form factor in the electromagnetic Dalitz decay $J/\psi \to e^+e^- \pi^0$ using $(10087 \pm 44) \times 10^6$ $J/\psi$ events collected by the BESIII…

We report on the computation of amplitudes describing the radiative decay processes $J/\psi \to \gamma \, \eta$ and $J/\psi \to \gamma \, \eta'$ from first principles via lattice QCD. Using lattices with two degenerate flavors of light…

The \eta and \eta' transition form factors in the space-like region are analyzed at low and intermediate energies in a model-independent way through the use of rational approximants. The slope and curvature parameters of the form factors as…

We briefly summarize current experimental and theoretical results on the two important processes of the low-energy hadron physics involving neutral pions, the rare decay $\pi^0\to e^+e^-$ and the Dalitz decay of $\pi^0$, and provide a new…

We investigate the $(\pi^0,\eta,\eta')\to\gamma^*\gamma$ transitions both for the spacelike region and the timelike region using the light-front quark model (LFQM). In particular, we present the new direct method to explore the timelike…

With the recent investigations of $g^{\ast}g^{\ast}-\eta^{(\prime)}$ transition form factor and $\eta-\eta^{\prime}$ mixing scheme, we present an updated study of the radiative decays $J/\Psi\to\eta^{(\prime)}\gamma$ in perturbative QCD.…

The electromagnetic Dalitz decays $J/\psi\rightarrow\eta^{(\prime)}e^{+}e^{-}$ with large recoil momentum are studied in the framework of perturbative QCD. Meanwhile, the soft contributions from the small recoil momentum region are…

Using $(27.12\pm 0.14)\times10^8$ $\psi(3686)$ decays and data samples of $e^+e^-$ collisions with $\sqrt{s}$ from 4.130 to 4.780~GeV collected with the BESIII detector, we report the first observation of the electromagnetic Dalitz…

We reanalyze the eta-gamma and eta'-gamma transition form factors within the modified hard scattering approach on the basis of new experimental data from CLEO and L3. Our approach perfectly describes the experimental data over a wide range…

The low-energy electromagnetic form factors of the $\Delta$(1232)-to-nucleon transition are derived combining dispersion theory techniques and chiral perturbation theory. The form factors are expressed in terms of the well-understood pion…

The production of pseudo scalar, Eeta, Eta-prime, and vector, Omega, Rho, Phi, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross…

The Dalitz decays eta -> e^+e^-g and omega -> pi^0 e^+e^- have been measured in the g p -> eta p and g p -> omega p reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope…

We briefly summarize current experimental and theoretical results on the $\pi^0$ Dalitz decay, including the new value for the ratio $R={\Gamma(\pi^0\to e^+e^-\gamma(\gamma))}/{\Gamma(\pi^0\to\gamma\gamma)}=11.978(6)\times10^{-3}$, which is…

The amplitude of the Dalitz decay pi0 -> e+ e gamma is studied and its model-independent properties are discussed in detail. A calculation of radiative corrections is performed within the framework of two-flavour chiral perturbation theory,…

Preliminary results for the Dalitz plot distribution of $\eta^\prime\to\eta\pi\pi$ decays in the frameworks of Large-$N_c$ Chiral Perturbation Theory and Resonance Chiral Theory are given. We hope our results to be of some relevance for the…

Using a data sample of $(10087\pm44)\times 10^6$ $J/\psi$ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process $J/\psi \to e^+ e^- \eta(1405)$ is observed via the decay $\eta(1405) \to…

With a sample of $(10087\pm44)\times10^{6}$ $J/\psi$ events accumulated with the BESIII detector, we analyze the decays $\eta'\rightarrow\pi^+\pi^-l^+l^-(l=e,$ $\mu)$ via the process $J/\psi\rightarrow\gamma\eta'$. The branching fractions…

Using a sample of about 10 billion $J/\psi$ events collected at a center-of-mass energy $\sqrt s = 3.097$ GeV with the BESIII detector, the electromagnetic Dalitz decays $J/\psi \to e^+e^- \pi^+ \pi^- \eta'$, with $\eta'\to\gamma\pi^+…

The next-to-leading-order $O(1/Q^4)$ power correction for $\eta\gamma$ and $\eta^\prime\gamma$ form factors are evaluated and employed to explore the $\eta-\eta^\prime$ mixing. The parameters of the two mixing angle scheme are extracted…

The KLOE results on the measurement of the transition form factors of the eta and pi0 mesons in phi Dalitz decays are presented, and the determination of the Gamma(eta->gamma gamma) in gamma gamma processes is also reported. The prospects…