相关论文: Coherent electroproduction of vector mesons on spi…
We provide an analysis of vector meson photoproduction in the channel of the vector meson decaying into a pseudoscalar meson plus a photon, i.e. $V\to P\gamma$. It is shown that non-trivial kinematic correlations arise from the measurement…
A theoretical formalism leading to elegant derivation of formulae for all spin observables is outlined for photo production of mesons with arbitrary spin parity $s^{\pi}$. The salient features of this formalism based on irreducible tensor…
A model based on Reggeon field theory is used for the description of the photo- and electroproduction of vector mesons ($\rho^0, \omega, \phi, J /\psi$) on the proton. Its main feature is the dependence of the Pomeron intercept on the…
Relativistic heavy ions are copious sources of virtual photons. The large photon flux gives rise to a substantial photonuclear interaction probability at impact parameters where no hadronic interactions can occur. Multiple photonuclear…
The problem of determining completely the spin amplitudes of photoproduction of two pseudoscalar mesons on a nucleon from observables is studied. The procedure of reconstruction of the scattering matrix elements from a complete set of…
We derive helicity amplitudes for diffractive leptoproduction of the S and D wave states of vector mesons. We predict a dramatically different spin dependence for production of the S and D wave vector mesons. We find very small…
The number and type of measurements needed to ascertain the amplitudes for pseudoscalar meson photoproduction are analyzed in this paper. It is found that 8 carefully selected measurements can determine the four transversity amplitudes…
Exclusive $\rho^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0…
A new approach to identify the independent amplitudes along with their partial wave multipole expansions, for photo and electro-production is suggested,which is generally applicable to mesons with arbitrary spin-parity. These amplitudes…
Preliminary results on azimuthal asymmetries in leptoproduction of real photons on an unpolarized hydrogen target measured at the HERMES experiment are presented. The analysis of data taken with different beam charges and helicities allows…
We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons ($\rho,\omega,\phi$) is described via the excitation of nucleon resonances ($R$). The…
We consider the production of a lepton-antilepton pair by real photons off a hadronic target. The interference of one and two photon exchange amplitudes leads to a charge asymmetry term that may be calculated explicitly in the large-t limit…
The target asymmetry for electroproduction of vector mesons is investigated within the handbag approach. While the generalized parton distribution (GPD) H is taken from a previous analysis of the elctroproduction cross section, we here…
Leptogenesis is an attractive scenario in which neutrino masses and baryon asymmetry of the Universe are explained together under a minimal set of assumptions. After formulating the problem of initial conditions and introducing the strong…
Exclusive production of $\phi$ mesons on hydrogen and deuterium targets is studied in the HERMES kinematic region $1 < Q^{2} < 7$ GeV$^2$ and $3.0 < W < 6.3$ GeV. Spin density matrix elements and their $Q^{2}$ and $t$ dependences are…
The process of a light neutral vector meson electroproduction is studied in the framework of QCD factorization in which the amplitude factorizes in a convolution of the nonperturbative meson distribution amplitude and the generalized parton…
We provide a framework to analyze the electroproduction process ep -> ep rho with a polarized target, writing the angular distribution of the rho decay products in terms of spin density matrix elements that parameterize the hadronic…
We calculate the nuclear cross section for vector meson exclusive photoproduction within the QCD color dipole picture and in the Regge approach. For the former approach, we have considered the phenomenological saturation model, whereas for…
High-statistics total cross sections for the vector meson photoproduction at the threshold: $\gamma p\to\omega p$ (from A2 at MAMI, ELPH, and CBELSA/TAPS), $\gamma p\to \phi p$ (from CLAS and LEPS), and $\gamma p\to J/\psi p$ (from GlueX)…
We have addressed the study of non-leptonic weak decays of heavy hadrons ($\Lambda_b, \Lambda_c, B$ and $D$), with external and internal emission to give two final hadrons, taking into account the spin-angular momentum structure of the…