Related papers: Meson resonances in forward-angle $\pi^+\pi^-$ pho…
Electroproduction of $\pi^+$ above the resonance region is analyzed in the Regge model for $\pi+\rho$ exchanges. Importance of the roles of pion and proton form factors in the process is discussed in comparison with existing models of…
A joint analysis of the pi+pi- and pi0pi0 S-wave amplitudes including results of three experiments has been performed. Using our theoretical model of the pion-pion production in which not only the pion exchange but also the a1(1260) meson…
Photo-production of excited mesons in the 1-2 GeV mass range decaying via multi-pion or multi-kaon emission has been investigated at the TJNAF\thanks{This work was supported by the U.S. Department of Energy and The U.S. National Science…
We study the $D_s^+ \rightarrow \pi^+ \, \pi^+ \, \pi^-$ and $D_s^+ \rightarrow \pi^+ \, K^+ \, K^-$ decays adopting a mechanism in which the $D_s^+$ meson decays weakly into a $\pi^+$ and a $q\bar{q}$ component, which hadronizes into two…
In the present paper we investigate pi0 pi0 and pi(+/-)pi0 photoproduction off complex nuclei at incident beam energies of 400-460 MeV. Simulations of two pion photoproduction on protons and nuclei are performed by means of a semi-classical…
The model of the pure one-pion exchange mechanism, which gives a good description of the GAMS results on the alteration of the $S$-wave $\pi^0\pi^0$ mass spectrum in the $f_0(980)$ region in the reaction $\pi^-p\to\pi^0\pi^0n$ with…
We describe the $\pi\pi$ $S$-wave in $D^+ \to\pi^+ \pi^- \pi^+$ decays using a unitary model for the $\pi\pi$ Final State Interactions (FSI). The three body decay is treated as a quasi two-body process where, at the weak vertex, the D meson…
A dynamical model for S-- and P--wave correlated $2 \pi$ (and $K \bar K$) exchange between a kaon and a nucleon is presented, starting from corresponding $N \bar N \rightarrow K \bar K$ amplitudes in the pseudophysical region, which have…
Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction $\gamma p\to p\pi^0$ for photon energies between 0.85 and 2.50 GeV. The $\pi^0$ mesons are observed in their dominant neutral decay mode:…
A theoretical model of two-pion photoproduction is presented. The model encodes the prominent $\rho(770)$ resonance and the expected leading background contribution coming from the Deck mechanism. To validate the model, angular moments are…
Based on the field-theory-inspired approach, a new expression for the pion form factor F_pi is proposed. It takes into account the pseudoscalar meson loops $\pi^+\pi^-$ and $K\bar K$ and the mixing of $\rho(770)$ with heavier $\rho(1450)$…
We have analyzed the K+K- photoproduction on hydrogen in the effective mass region around the mass of the phi(1020) meson. The interference of the S-wave contribution with the P-wave has been studied. Both scalar resonances f0(980) and…
We report a study of the central exclusive production of $\pi^{+} \pi^{-}$ and $K^{+}K^{-}$ pairs in high energy hadron-hadron collisions. The amplitude is calculated in the Regge approach including both pomeron and secondary reggeon…
The interference between the Pomeron and possible odderon mechanisms of diffractive pi+pi- photoproduction results in charge asymmetry of the produced pions. The observation of charge asymmetry of pions at moderate M_{pi+pi-} will be an…
We consider the production of $B^* \bar B^*$ meson pairs in $e^+e^-$ annihilation near the threshold. The rescattering due to pion exchange between the mesons results in a mixing between three partial wave amplitudes: two $P$-wave with the…
An experiment on the radiative pi^+ meson photoproduction from the proton (gamma p->gamma pi^+ n) was carried out at the Mainz Microtron MAMI in the kinematic region 537 MeV <E_{gamma}<817 MeV, 140^o<theta_{gamma-gamma'}^cm<180^o. The pi^+…
We investigate the discovery potential of the $a_1(1260)$ photoproduction in the $\gamma p \to a_1(1260)^+ n$ and $\gamma p \to \pi^+\pi^+\pi^- n$ reactions via the $\pi$-exchange mechanism. For the $\gamma p \to \pi^+\pi^+\pi^- n$…
The leading twist parametrization of dipion mass distribution in hard exclusive reactions is proposed. Its parameters are related to quark distributions (usual and skewed) in the pion and to distributions amplitudes of mesons ($\pi$,…
We study the photoproduction of exclusive $2\pi^+2\pi^-$ mesons in ultra-peripheral heavy-ion collisions at RHIC and LHC energies. Predictions in photon-nucleus interactions are calculated for various resonances at central and forward…
We analyse the pion electromagnetic, charged-current, and $\pi\gamma$ transition form factors at timelike momentum transfers $q$, $q^2=s\le 1.4$ GeV$^2$, using a dispersion approach. We discuss in detail the propagator matrix of the…