Related papers: $\eta_{c2}(^1D_2)$ and its electromagnetic decays
Rare decays of light mesons may be a discovery window for a new weakly coupled forces hidden at low energy QCD scale. BES-III Collaboration reported the observation of the rare decay $\eta'\rightarrow\pi^0\gamma\gamma$. The observed decay…
The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the $\eta_c$ meson. The 2024 result is significantly larger than most theoretical and empirical expectations, while a subsequent measurement…
The full width of the light isovector hybrid meson $H_{\mathrm{V}}$ with spin-parities $1^{\mathrm{-+}}$ and content $(\overline{u}gu-\overline{d}gd)/ \sqrt{2}$ is evaluated by considering the decays $H_{\mathrm{V}} \to…
We study the anomalous dimension $\eta$ of homogeneous interacting single-component Bose-Einstein condensates at finite temperatures for $d\lesssim 4$ dimensions. This $\eta$ is defined in terms of the one-particle density matrix $\rho({\bf…
The charm semileptonic decays $D^+\to\eta e^+\nu_{e}$ and $D^+\to\eta'e^+\nu_{e}$ are studied with a sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 fb$^{-1}$ collected at $\sqrt{s}$ = 3.773 GeV with the…
A new measurement of the rare decay \phi \to \eta' \gamma performed with the CMD-2 detector at Novosibirsk is described. Of the data sample corresponding to the integrated luminosity of 14.5 pb^{-1}, twenty one events have been selected in…
Using a data sample of $1.31\times10^{9} ~J/\psi$ events collected with the BESIII detector, a search for $\eta'\to\gamma\gamma\eta$ via $J/\psi\to\gamma\eta'$ is performed for the first time. No significant $\eta'$ signal is observed in…
Using $(2712.4\pm14.3)\times10^{6}$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII collider, the decay $\eta_c\to\gamma\gamma$ in $J/\psi\to\gamma\eta_c$ is observed. We determine the product branching fraction…
We present an exploratory lattice study for the two-photon decay of $\eta_c$ using $N_f=2$ twisted mass lattice QCD gauge configurations generated by the European Twisted Mass Collaboration. Two different lattice spacings of $a=0.067$fm and…
Recently, LHCb reported the radiative-decay ratio ${\cal R}^{\psi\gamma}\equiv {\cal B}[X(3872)\to \psi'\gamma]/{\cal B}[X(3872)\to J/\psi\gamma]=1.67\pm 0.25$ extracted from $B^+\to K^+(J/\psi\gamma, \psi'\gamma)$. This result differs…
It has been realized for a long time that knowing the \eta and \eta' 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…
The properties of the $\DsTT$ and $\DsFE$ mesons are studied using 125 ${\rm fb}^{-1}$ of $e^+e^- \to c \bar{c}$ data collected by the BaBar experiment. Preliminary mass estimates of $[2318.9\pm 0.3 ({\rm stat.}) \pm 0.9 ({\rm syst.})]$…
We present the first measurement of the D*+ width using 9/fb of e+e- data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of…
Based on a sample of $(1.0087\pm0.0044)\times10^{10}$ $J/\psi$ events collected at BESIII, the transition form factor of the $\eta$ meson is extracted by analyzing $J/\psi\to\gamma\eta',~\eta'\to\pi^+\pi^-\eta,~\eta\to\gamma l^+l^-$…
Considering the mass, parity and $D^0 p$ decay mode, we tentatively assign the $\Lambda_c(2940)$ as the $P-$wave states with one radial excitation. Then, via studying the strong decay behavior of the $\Lambda_c(2940)$ within the $^3P_0$…
The process $e^+e^-\to\eta\eta\gamma$ is studied in the center-of-mass energy range 1.17-2.00 GeV using data with an integrated luminosity of 201 pb$^{-1}$collected by the SND detector at the VEPP-2000 $e^+e^-$ collider. The…
We report the first evidence for the eta_b(2S) using the h_b(2P)->eta_b(2S)gamma transition and the first observation of the h_b(1P)->eta_b(1S)gamma and h_b(2P)->eta_b(1S)gamma transitions. The mass and width of the eta_b(1S) and eta_b(2S)…
This work delves into the phenomenology of electronic inclusive decays of $D$ mesons, encompassing $D^0, D^+, D^+_s\to Xe^{+}\nu$. The theoretical formulas for the decay widths and electron energy moments of these decays are presented as…
Using $448.0 \times 10^6$~$\psi(3686)$ events collected with the BESIII detector, an amplitude analysis is performed for $\psi(3686)\to\gamma\chi_{c1}$, $\chi_{c1}\to\eta\pi^+\pi^-$ decays. The most dominant two-body structure observed is…
We systematically investigate the mass spectrum and two-body open-charm strong decays of charmonium states in a coupled-channel model where the $^3P_0$ quark-antiquark pair creation mechanism is employed. The results of masses, mass shifts,…