相关论文: On the spin-observables in pseudoscalar meson phot…

We analyze the electroproduction of pseudoscalar mesons within the handbag approach. To investigate these reactions, we consider the leading-twist contribution together with the transversity twist-3 effects that are crucial in the…

It is shown that most of the available data on the $pp\to pp\eta$ reaction, including the invariant mass distributions in the $pp\to pp\eta$ reaction recently measured at COSY, can be understood in terms of the partial-wave amplitudes…

Particles in a hidden sector can potentially acquire a small electric charge through their interaction with the Standard Model and can consequently be observed as millicharged particles. We systematically compute the production of…

The pattern of calculation of amplitudes of a series of processes in the field of an intensive laser wave, in which two fermions $(p; p')$ and two real photons $(k_1; k_2)$ participate, is considered. In relation to one-photon processes,…

Exclusive pseudoscalar meson production in ep scattering at high energies is a direct probe for a possible "odderon" exchange in soft hadronic processes. Using a simple phenomenological ansatz for the odderon, we demonstrate how it can be…

We have carried out exclusive measurements for the photoproduction of an $\eta$ meson from a proton target with an egg-shaped calorimeter made of BGO crystals (BGOegg) and forward charged-particle detectors at the SPring-8 LEPS2 beamline.…

Partial wave scattering amplitudes in baryon-baryon and baryon-antibaryon collisions and amplitudes for the production and decay of baryon resonances are constructed in the framework of the spin-momentum operator expansion method. The…

We report a measurement of the $\pi^-$ photoproduction beam asymmetry for the reaction $\vec{\gamma} p \rightarrow \pi^- \Delta^{++}$ using data from the GlueX experiment in the photon beam energy range 8.2--8.8 GeV. The asymmetry $\Sigma$…

The review of developed by the authors new techniques for covariant calculation of matrix elements in QED, the so-called formalism of "Diagonal Spin Basis" (DSB), is presented. In DSB spin 4-vectors of in- and out- fermions are expressed…

The exclusive reaction $\gamma p \to p \pi^+ \pi^-$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National…

Single nucleon knockout reactions must be described in a consistent framework in order to extract information about nuclear structure and reaction mechanisms. Consistent relativistic models for the direct knockout contribution to the (e,…

Formal expressions are developed for the general five-fold differential cross section of incoherent $\pi$-photoproduction on the deuteron including beam and target polarization. The polarization observables of the cross section are…

We analyze the production of $\phi$ mesons in $\pi N$ and NN reactions in the near-threshold region, using throughout the conventional ``non-strange'' dynamics based on such processes which are allowed by the non-ideal $\omega-\phi$ mixing.…

Photoproduction of eta-mesons off 3He has been studied at the MAMI accelerator using the Crystal Ball/TAPS detector setup. The total cross section for the coherent eta-photoproduction was measured with improved statistical quality. Both,…

Coherent photoproduction of $\pi^0$-mesons from threshold ($E_{th} \approx$ 136 MeV) throughout the $\Delta$-resonance region and of $\eta$-mesons close to the production threshold ($E_{th} \approx$ 570 MeV for $\eta$) has been measured for…

The LEPS/SPring-8 experiment made a comprehensive measurement of the spin-density matrix elements for $\gamma p \to \phi p$, $\gamma d \to \phi p n$ and $\gamma d \to \phi d$ at forward production angles. A linearly polarized photon beam at…

We investigate pion photoproduction off the proton in a manifestly gauge-invariant chiral unitary extension of chiral perturbation theory. In a first step, we consider meson-baryon scattering taking into account all next-to-leading order…

We study the pair production of $B_c$ mesons in the photon-photon interaction in the framework of perturbative quantum chromodynamics and the relativistic quark model. The production amplitudes of a pair of pseudoscalar and vector $B_c$…

Bethe-Salpeter equation is applied to $p$-$n$ elastic scattering. The spin observables are calculated by the M matrix similar to $p$-$p$ case. The parameters of the meson-exchange model are used with the cut-off for the pion exchange…

The recent observation of the X(2600) resonance by the BESIII Collaboration has motivated a renewed interest in the spectroscopy of light mesons, particularly pseudotensor states. However, a significant theoretical gap exists in the poorly…