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

The light unflavoured meson $\eta/\eta^{\prime}$ decays are valuable for testing non-perturbative quantum chromodynamics and exploring new physics beyond the Standard Model. This paper describes a series of event generators, including…

The $\Delta(1232) \to \gamma^\ast N$ magnetic dipole form factor ($G_M^\ast$) is described here within a new covariant model that combines the valence quark core together with the pion cloud contributions. The pion cloud term is…

We study the reactions e+e- --> e+e- eta (eta') in the single-tag mode and measure the gamma gamma* --> eta (eta') transition form factors in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 469 fb-1 of integrated…

The reaction $e^+e^- \to \bar \Lambda \Lambda$ is investigated for energies close to the threshold. Specific emphasis is put on the role played by the interaction in the final $\bar \Lambda \Lambda$ system which is taken into account…

The photon-meson transition form factors of light pseudoscalar mesons $\pi ^{0}$, $\eta$, and $\eta ^{\prime}$ are systematically calculated in a light-cone framework, which is applicable as a light-cone quark model at low $Q^{2}$ and is…

The results of the search for the $e^+e^-\to\eta^{\prime}\gamma$ process in the center-of-mass energy range from 1.075 to 2 GeV are presented. We analyze data with an integral luminosity of 746 pb$^{-1}$ accumulated with the SND detector at…

It is reported on predictions for the $\pi$-$\gamma$ transition form factor obtained within a perturbative approach which includes transverse momentum effects and Sudakov corrections. The results clearly favor distribution amplitudes close…

We report the first observation of the decay D^+ -> eta' e^+ nu_e in two analyses, which combined provide a branching fraction of B(D+ -> eta' e nu) = (2.16 +/- 0.53 +/- 0.07) x 10^{-4}. We also provide an improved measurement of B(D+ ->…

We present a recent treatment of the $\pi^0\gamma^\star\gamma$ transition form factor in the coupled Schwinger-Dyson and Bethe-Salpeter approach to stress the desirability of measuring it at CEBAF.

The $\eta$-$\eta^\prime$ pseudoscalar mixing angle and the gluonium content of the $\eta^\prime$ meson are deduced from an updated phenomenological analysis of $V\to P\gamma$ and $J/\psi\to VP$ decays. In absence of gluonium, the value of…

It has been realized for a long time that knowing the eta and eta^prime wave functions in terms of quark and gluon components probes our understanding of non-perturbative QCD dynamics. Great effort has been given to this challenge -- yet no…

We develop a covariant model for the $\gamma^\ast N \to N(1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^2$ is positive. Our starting point is the covariant spectator quark model…

We present a detailed study of the exclusive radiative decays $Z\to\eta^{(\prime)}\gamma$ employing the QCD factorization approach. We derive a factorization formula for the decay amplitudes valid at leading power in an expansion in…

Motivated by the successful application of Heavy Quark Effective Field Theory in describing decays from heavy to light mesons, this work explores its applicability to the semileptonic decays of charmed mesons. So in this paper we…

In the present work, we analyze the properties of the transition form factors (TFFs) for the $\gamma\gamma^*\to \eta^{(\prime)}$ process, employing the $\eta^{(\prime)}$-meson light-cone distribution amplitude (LCDA) derived within the…

The processes of $\eta_c (\eta_c')\to VV$ are supposed to be suppressed by the helicity selection rule (HSR) but found to be rather important decay modes in experiment for $\eta_c$. We try to distinguish the short-distance transitions via…

The quest for sources of the simultaneous violation of $C$ and $CP$ symmetry was popular in the 1960s, but has since been neglected for a long time. We revisit the operators that break $C$ and $CP$ for flavor-conserving transitions in both…

The possible range of $\eta-\eta'$ mixing angle is determined from the transition form factors $F_{\eta \gamma}(Q^2)$ and $F_{\eta' \gamma}(Q^2)$ with the help of the present experimental data. For such purpose, the quark-flavor mixing…

A study of $B^0$~and $B^0_s$ meson decays into $J/\psi\eta$~and $J/\psi\eta^{\prime}$ final states is performed using a data set of proton-proton collisions at centre-of-mass energies of 7 and 8TeV, collected by the LHCb experiment and…

Using a data sample of $(1.0087\pm 0.0044)\times 10^{10}$ $J/\psi$ events collected with the BESIII detector, the decays of $J/\psi\to\gamma\pi^{0} (\eta, \eta^\prime)\to\gamma\gamma\gamma$ are studied. Newly measured branching fractions…