Related papers: Di-electron and two-photon widths in charmonium
We calculate the $\Lambda_c\bar{\Lambda}_c$ partial decay width of the excited vector charmonium states around 4.6 GeV with the quark pair creation model. We find that the partial decay width of the $\Lambda_c\bar{\Lambda}_c$ mode can reach…
We present a calculation of the two-photon and two-gluon widths for the equal mass quarkonium states $^1S_0$, $^3P_0$ and $^3P_2$ of the charmonium and upsilon systems. The approach taken is based on using the full relativistic…
The recently BaBar results raise the possibility that X(3872) has negative parity. This makes people reconsider assigning X(3872) to the $1{^1D_2}(c\bar c)$ state. In this paper we give a general form of the wave function of $2^{-+}$…
In this paper we present a measurement of the natural widths of $\Sigma_c^0$ and $\Sigma_c^{++}$. Using data from the FOCUS experiment, we find $\Gamma(\Sigma_c^0) = 1.55 +0.41/-0.37 \pm 0.38$ MeV/c^2 and $\Gamma(\Sigma_c^0) = 2.05…
We analyse data on pi pi and gamma gamma scattering below 700 MeV within an improved analytic K-matrix model. This model is based on an effective theory with couplings between resonances, hadrons and photons. The two-photon decay of a…
Recently the ATLAS and CMS experiments have presented data hinting at the presence of a Higgs boson at $m_h\simeq125$ GeV. The best-fit $h\rightarrow\gamma\gamma$ rate averaged over the two experiments is approximately $2.1\pm0.5$ times the…
We estimate the electromagnetic decay rates of $\chi_{c0}\rightarrow \gamma\gamma$ and $\chi_{c2}\rightarrow\gamma\gamma$ by taking into account both relativistic and QCD radiative corrections. The decay rates are derived in the…
The hadronic decay $\eta_c(2S) \to 3(\pi^+\pi^-)$ is observed with a statistical significance of 9.3 standard deviations using $(448.1\pm2.9)\times10^6$ $\psi(3686)$ events collected by the BESIII detector at the BEPCII collider. The…
Probing Higgs width $\Gamma_h$ is critical to test the Higgs properties. In this work we propose to measure $\Gamma_h$ at the $e^+e^-$ collider with a model-independent analysis under the Standard Model Effective Field Theory framework. We…
Dipion transitions of $\Upsilon (nS)$ with $n=5, n'=1,2,3$ are studied using the Field Correlator Method, applied previously to dipion transitions with $n=2,3,4$ The only two parameters of effective Lagrangian were fixed in that earlier…
Measurements of branching fractions for nine different final states, based on a data sample of approximately 4 million psi(2S) events collected with the BESI detector at the BEPC, are reported. Using the same event sample, radiative decays…
We perform a lattice QCD calculation of the $\eta_c\to2\gamma$ decay width using a model-independent method that requires no momentum extrapolation of the off-shell form factors. This method also provides a straightforward and simple way to…
The possibility to observe new bottomonium states with $J^{PC}= 1^{--}$ in the region $10.7-11.1$ GeV is discussed. The analysis of the di-electron widths shows that the $(n+1)^3S_1$ and $n^3D_1$ states ($n\geq 3$) may be mixed with a…
For a Higgs boson below the $W^\pm$ threshold, the $\gamma \gamma$ collider option of a future linear $e^+ e^-$ machine is compelling. In this case one can measure the ``gold-plated'' loop induced $\Gamma (H \longrightarrow \gamma \gamma)$…
Many vector charmonium-like states have been reported recently in the cross sections of $e^+e^- \rightarrow \omega\chi_{c0}$, $\pi^{+}\pi^{-}h_c$, $\pi^{+}\pi^{-}J/\psi$, $\pi^{+}\pi^{-}\psi(3686)$ and $\pi^{+}D^{0}D^{*-}+c.c.$ To better…
We report a direct search for a new gauge boson, $X$, with a mass of $17~\text{MeV}/c^2$, which could explain the anomalous excess of $e^+e^-$ pairs observed in the $^8\text{Be}$ nuclear transitions. The search is conducted in the…
We calculate the two-loop QCD corrections to paracharmonium decays $eta_{c} rightarrow gamma gamma$ and $eta_{c} rightarrow g g$ involving light-by-light scattering diagrams with light quark loops. Artificial large mass expansion and…
We compute the electric dipole transitions $\chi_{bJ}(1P)\to \gamma\Upsilon(1S)$, with $J=0,1,2$, and $h_{b}(1P)\to \gamma\eta_{b}(1S)$ in a model-independent way. We use potential non-relativistic QCD (pNRQCD) at weak coupling with either…
We analyze 13.8 \rm fb^{-1} of the integrated e^+e^- luminosity collected at 10.6 GeV center-of-mass energy with the CLEO II and CLEO II.V detectors to study exclusive two-photon production of hadrons with masses below 1.7{\rm \ GeV/c^2}…
We revisit the calculation of the width for the radiative decay of a $1^{+-}$ heavy $Q \bar Q$ meson via the channel $1^{+-} \to 0^{-+} +\gamma$ in the covariant light-front quark model. We carry out the reduction of the light-front…