Related papers: On the two-photon decay width of the sigma meson
We calculate the decay width of the $\Lambda_{c}^{+}\to\Sigma^{+}\gamma$ using light-cone sum rules. For the initial quark radiation an effective Hamiltonian is constructed, where the internal quark line shrinks to a point. The final quark…
Based on a data sample of 106 M $\psi^{\prime}$ events collected with the BESIII detector, the decays $\psi^{\prime}\ar\gamma\chi_{c0, 2}$,$\chi_{c0, 2}\ar\gamma\gamma$ are studied to determine the two-photon widths of the $\chi_{c0, 2}$…
We propose a direct method to calculate the decay width of a hadron decaying to two photons, which is conventionally obtained by an extrapolation for various off-shell form factors. The new method provides an simple way to examine the…
The two-photon width of chi_c2 (^3P_2) state of charmonium has been measured using 14.4 fb^-1 of e+e- data taken at sqrt{s} = 9.46-11.30 GeV with the CLEO III detector. The two-photon fusion reaction studied is e+e- -> e+e- gamma gamma,…
We analyze the end-point region of the photon spectrum in semi-inclusive radiative decays of very heavy quarkonium (m alpha_s^2 >> Lambda_QCD). The S- and P-wave octet shape functions are calculated. When they are included in the analysis…
In this work we calculate the mass spectrum of charmonium for $1P,...,3P$ states of $0^{++}$ , $1^{++}$, as well as for $1S,...,4S$ states of $0^{-+}$, and $1S, ...,5D$ states of $1^{--}$ along with the two-photon decay widths of ground and…
In this article we propose standard model strictly forbidden decay modes, quarkonia (QQ(1^{--}) = J/psi, Upsilon) decays into two photons, as a possible signature of the space-time non-commutativity. An experimental discovery of J/psi ->…
We calculate low-energy meson decay processes and pion-pion scattering lengths in a two-flavour linear sigma model with global chiral symmetry, exploring the scenario in which the scalar mesons $f_0$(600) and $a_0$(980) are assumed to be…
We obtain the width of the $\omega$ meson in dense nuclear matter by taking into account (i) the free decay of the $\omega$ into three pions, which is dominated by $\rho \pi$ mode, (ii) the processes induced by a vector-baryon interaction…
The spectra of the scalar ($\sigma$) and vector ($\omega$) mesons in nuclear matter are studied in detail using the quark-meson coupling (QMC) model. It is shown that above normal nuclear matter density the effects of $\sigma$-$\omega$…
We study the two photon decay of neutral scalars below 1.5 GeV in the context of a recently proposed chiral model for bar{q}q and bar{q}bar{q}qq states. We find good agreement with experimental results for the a_{0}(980)->gamma gamma. Our…
A rigorous QED theory of the multiphoton decay of excited states in hydrogen atom is presented. The "two-photon" approximation is formulated which is limited by the one-photon and two-photon transitions including cascades transitions with…
Two-photon decay rates of pseudoscalar, scalar and tensor states of charmonium and bottomonium are calculated in the framework of the relativistic quark model. Both relativistic effects and one-loop radiative corrections are taken into…
By means of effective field theory techniques, we study the modifications of some properties of weakly coupled heavy quarkonium states propagating through a quark-gluon plasma at temperatures much smaller than the heavy quark mass, m_Q. Two…
The decay width of a phi meson is reduced from its vacuum value as its mass decreases in hot hadronic matter as a result of the partial restoration of chiral symmetry. This reduction is, however, cancelled by collisional broadening through…
In this exploratory study, two photon decay widths of pseudo-scalar ($\eta_c$) and scalar ($\chi_{c0}$) charmonium are computed using two ensembles of $N_f=2$ twisted mass lattice QCD gauge configurations. The simulation is performed two…
A simple matching procedure is proposed to extract constraints on effective meson theories. In this way, a QCD prediction for the pion decay constant is found, F(pi)=2 m(pi)/pi, i.e. approximately 90MeV. The same procedure also determines…
The quark-level linear sigma model is employed to compute a variety of electromagnetic and weak observables of light mesons, including pion and kaon form factors and charge radii, charged-pion polarizabilities, semileptonic weak $K_{\ell3}$…
We present a theoretical analysis of two-photon absorption of classical and squeezed light valid when one-photon absorption to an intermediate state is either resonant or far-detuned from resonance, and in both the low and high intensity…
Electromagnetic interactions of the ground and first radial excited states of $\eta$ and $\eta'$ mesons in the framework of the extended $U(3)\times U(3)$ NJL model are considered. The radial excitations are described with the help of…