Related papers: Process eta -> pi^0 gamma gamma in the Nambu-Jona-…
The branching ratios and photon spectra of the rare processes rho(omega)-> pi^0 pi^0 gamma, rho(omega) -> eta pi^0 gamma are calculated in the framework of the standard local quark Nambu--Jona-Lasinio (NJL) model. Three types of diagrams…
We calculate within the Extended Nambu--Jona-Lasinio model the leading in $1/N_c$ contribution to $\gamma\gamma\to\pi^0\pi^0$ to all orders in the external momenta and quark masses. This result is then combined with the known two-loop…
We study the $\eta \to \pi^0 \gamma \gamma$ decay via the quark-box diagram in the three-flavor Nambu--Jona-Lasinio model that includes the $U_A (1)$ breaking effect. We find that the $\eta$-meson mass, the $\eta \to \gamma \gamma$ decay…
The decay \phi -> f_0(980) \gamma and process e^+e^- -> \phi f_0(980) are considered within the local Nambu-Jona-Lasinio model. In the amplitudes of these processes contributions of s-quark and kaon loops are taken into account. The kaon…
In the framework of the extended Nambu-Jona-Lasinio model, the processes $\tau \to \pi \pi \eta(\eta')\nu_\tau$ and $\tau \to \pi\eta\eta(\eta')\nu_\tau$ are considered taking into account mesons in the ground and first radially excited…
The full and differential widths of the decay $\tau \rightarrow K^{0}K^{-}\nu_{\tau}$ are calculated in the framework of the extended Nambu-Jona-Lasinio model. The contributions of the subprocesses with the intermediate vector mesons…
The decays $\tau \rightarrow (\eta,\eta') K^{-} \nu_{\tau}$ are described in the framework of the extended Nambu-Jona-Lasinio model. Both full and differential widths of these decays are calculated. The vector and scalar channels are…
Within the Extended Nambu Jona-Lasinio model, we calculate the $O(p^6)$ counterterms entering the low-energy expansion of the $\gamma \gamma \to \pi^0 \pi^0$ and the $\eta \to \pi^0 \gamma \gamma$ amplitudes in Chiral Perturbation Theory.…
In the extended Nambu--Jona-Lasinio model, the decay widths of the processes $\tau \to [\omega(782), \phi(1020)] K^{-} \nu_{\tau}$ were calculated. The intermediate channels with axial vector ($K_{1}(1270)$, $K_{1}(1400)$ and…
The polarization effects of the processes $\tau \rightarrow K^{-} \pi^{0} \nu_{\tau}$ are described in the framework of the Nambu--Jona-Lasinio model. The intermediate vector meson $K^{*}(892)$ is taken into account. The contribution of…
Some properties of the rho vector meson are calculated within the Nambu-Jona-Lasinio model, including processes that go beyond the random phase approximation. To classify the higher order contributions, we adopt $1/N_c$ as expansion…
We calculate the P0 to gamma gamma, V0 to P0 gamma and V0to V'0 gamma gamma decays in the framework of a U(3)xU(3) linear sigma model which includes constituent quarks. For the first two decays this approach improves results based on the…
The two-photon decay widths of scalar mesons \sigma(600), f_0(980) and a_0(980) are calculated in framework of the local Nambu-Jona-Lasinio model. The contributions of the quark loops (Hartree-Fock approximation) and the meson loops (next…
In this paper, the width of the decay $\tau \rightarrow K^{-}\pi^{0}\nu_{\tau}$ is calculated in the framework of the Nambu-Jona-Lasinio model. The contributions of the intermediate vector $K^{*}(892)$ and scalar $K_{0}^{*}(800)$ mesons are…
The decays pi^0, eta, eta-prime -> gamma gamma are investigated up to next-to-next-to-leading order in the framework of the combined 1/N_c and chiral expansions. Without mixing of the pseudoscalar mesons the N_c independence of the pi^0 and…
In the extended NJL model the radiative decay widths of the radially excited states of the pseudoscalar $\pi$, $\eta$, and $\eta'$ mesons are calculated. The predictions for the decay widths of the processes…
We improve the calculations of the $\eta \to \pi^0 \gamma \gamma$ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the $a_0(980)$ resonance and fixing…
The cross section of the process e+ e- --> pi0 pi0 gamma has been measured in the c.m. energy range 600--970 MeV with the CMD-2 detector. The following branching ratios have been determined: B(rho --> pi0 pi0 gamma) =(5.2^{+1.5}_{-1.3} +-…
The transition amplitude for $\pi K$ scattering is evaluated within the SU(3) Nambu--Jona-Lasinio model. Ordering terms according to the expansion in $1/N_c$ leads to a box-like diagram, $t$ channel diagrams that admit scalar isoscalar…
The e+e- -> pi0 pi0 gamma process was studied in the SND experiment at VEPP-2M e+e- collider in the energy region 0.60-0.97 GeV. From the analysis of the energy dependence of measured cross section the branching ratios B(omega -> pi0 pi0…