Related papers: e^+ e^- Annihilation into J/psi + J/psi

We calculate the form factor and cross section of the excited charmonium production process $e^{+}+e^{-}\rightarrow \psi \left ( 2S \right )+\eta _{c}$ by light-cone sum rules. In our method, the form factor depends on the distribution…

Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, where $\psi$ is a vector charmonium,…

We perform a full amplitude analysis of the process $e^+ e^- \rightarrow J/\psi D \bar{D}$, where $D$ refers to either $D^0$ or $D^+$. A new charmoniumlike state $X^*(3860)$ that decays to $D \bar{D}$ is observed with a significance of…

Polarizations of the prompt $J/\psi$'s produced in the $e^+e^-$ annihilation at CLEO energy ($\sqrt{s} = 10.58$ GeV) are considered in the framework of NRQCD factorization formalism. We find that the $J/\psi$ polarization has strong…

Recent results from BES and CLEOc experiments on charmonium decays using J/psi, psi' and psi'' data samples collected in e+e- annihilation are reviewed, including the measurement of the relative phase between strong and electromagnetic…

The cross-section for the production of $t\bar{t}$ pairs in $e^+e^-$-annihilation via a virtual photon is determined up to order $\alpha_s^2$. For the cm-energies of interest the effect of the top mass may not be considered as a small…

In this work, we study the exclusive decay of $\Upsilon$ into $J/\psi$ in association with $\eta_c$ ($\chi_{c0,1,2}$). The decay widths for different helicity configurations are evaluated up to QCD next-to-leading order within the…

We examine the processes $e^+ e^-\longrightarrow W^+ W^-$ and $Z^0 Z^0$ in the context of the $SP(6)_L\otimes U(1)_Y$ model. We find that there are significant deviations in the total cross sections $\sigma (s)$ from the standard model…

A study of $B^+ \rightarrow J/\psi \eta K^+$ decays, followed by $J/\psi \rightarrow \mu^+ \mu^-$ and $\eta \rightarrow \gamma \gamma$, is performed using a dataset collected with the LHCb detector in proton-proton collisions at…

We calculate cross sections of a pair $B_c$ meson production on the basis of two-photon mechanism from electron-positron annihilation. We investigate the production cross sections in nonrelativistic approximation and with the account of…

We compute the J/psi+gamma invariant-mass distributions from the QCD subprocess g + g --> J/psi+gamma. At large masses, this subprocess is the dominant mechanism for J/psi+gamma production, and data could provide a good test of QCD. The…

The rate for the production of a pair of massive fermions in $e^+ e^-$ annihilation plus real or virtual radiation of a pair of massless fermions is calculated analytically. The contributions for real and virtual radiation are displayed…

We study the direct production of the $J^{PC}=1^{++}$ charmonium state $\chi_{c1}(1P)$ in electron-positron annihilation by carrying out an energy scan around the mass of the $\chi_{c1}(1P)$. The data were collected with the BESIII detector…

We investigate the direct photoproduction of $J/\psi+c\bar{c}$ at $ep$ colliders with different center of mass energies in this paper. For the color-singlet part we take into account the contribution from QED subprocess as well as the QCD…

The processes of D^{(*)}-mesons and \Lambda_c-baryons production in e^+e^--annihilation at 10.58 GeV and 91.18 GeV energies are concerned. At the 10.58 GeV energy the production of charmed particles via the B-mesons decays is also…

Based on the nonrelativistic QCD factorization approach, ${\mathcal O}(\alpha_s v^2)$ corrections to $\jpsi$ plus $\eta_c$ production in $e^+e^-$ annihilation at $\sqrt{s}=10.6 \gev$ is calculated in this work. The numerical results show…

To understand the reliability of the charmonia suppression as a signature of the Quark-Gluon Plasma formation in nucleus-nucleus collisions it is important first to understand the details of the production of J/psi and psi' in pA…

By analyzing the data sets of 17.3 pb$^{-1}$ taken at $\sqrt{s}=3.773$ GeV and 6.5 pb$^{-1}$ taken at $\sqrt{s}=3.650$ GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 12 exclusive light…

Recent results on charmonia decays at BES/BEPC are reported, including the observation of psi'-->K_S K_L, psi'--> Vector + Tensor for the measurement of the relative phase between the strong and electromagnetic decays of psi' and a test of…

A search is performed for the central exclusive production of pairs of charmonia produced in proton-proton collisions. Using data corresponding to an integrated luminosity of $3{\rm\ fb}^{-1}$ collected at centre-of-mass energies of 7 and 8…