相关论文: Constraints on vector meson photoproduction spin o…
This article reviews the current status of experimental results obtained in the measurement of light vector mesons produced in proton-proton and heavy ion collisions at different energies. The review is focused on two phenomena related to…
A recently developed model for $\rho$-meson propagation in dense hadronic matter is applied to total photoabsorption cross sections in $\gamma$-proton and $\gamma$-nucleus reactions. Within the vector dominance model the photon coupling to…
A complete set of linearly independent observables in Compton scattering with arbitrarily polarised real photons off an arbitrarily polarised spin-1 target is introduced, for the case that the final-state polarisations are not measured.…
In this work, we derive novel constraints on scalar-tensor theories from neutrino physics. Spatial variations of the background scalar field effectively generate density and position-dependent Standard Model masses, including neutrinos.…
A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $\eta$ and $\pi^0$ mesons. Different interpretations of a dip-bump structure of the $\eta$…
We study the spin-dependent cross-sections of vector meson photoproduction for longitudinally and transversely polarized photons within a QCD- model. The dependence of the $\sigma_T/\sigma_L$ ratio on the photon virtuality and on the meson…
It is shown that general dilepton angular distribution (with parity violating terms taking into account) in vector particle decays can be described through a set of five SO(3) rotational-invariant observables. These observables are derived…
We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive $\omega$ meson muoproduction on the proton at COMPASS using 160 GeV/$c$ polarised $ \mu ^{+}$ and $ \mu ^{-}$ beams impinging on a liquid hydrogen target.…
Spin-observables in pseudoscalar meson photoproduction is discussed. This work is complementary to the earlier works on this topic. Here, the reaction amplitude is expressed in Pauli-spin basis which allows to calculate all the observables…
Some open topics in the field of low energy photon-nucleon interactions are discussed--which in my opinion are of interest both for obtaining new information on nucleon structure as well as for precision tests of our theoretical…
Ultralight dark photons are compelling dark matter candidates, but their allowed kinetic mixing with the Standard Model photon is severely constrained by requiring that the dark photons do not collapse into a cosmic string network in the…
The cross section and decay angular distributions for the coherent \phi meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t =(p_{\gamma}-p_{\phi})^2 =-2 GeV^2/c^2, using the…
Spin-dependent quark densities, matrix elements of specific density operators in proton states of definite spin-polarization, indicate that the nucleon may harbor an infinite variety of non-spherical shapes. We show that these matrix…
Understanding the spin dynamics of strong interactions from the nonperturbative to the perturbative regime remains a challenge. Regge pole theory offers a phenomenological framework, but existing models fail to simultaneously describe cross…
We considered the electro- and photoproduction of \rho and other vector mesons with moderately large transverse momentum in the scattering of unpolarized electrons on unpolarized nucleons and nuclei. For these processes we have analyzed how…
Measuring the spin structure of protons and neutrons tests our understanding of how they arise from quarks and gluons, the fundamental building blocks of nuclear matter. At long distances the coupling constant of the strong interaction…
A truncated partial wave analysis for the photoproduction of two pseudoscalar mesons on a nucleon is discussed with respect to the determination of a complete set of observables. For the selection of such a set we have applied a criterion…
Spin observables for the three charge states of the pion for the pion photoproduction reaction on the deuteron, $\gamma d\to\pi NN$, with polarized photon beam and/or oriented deuteron target are predicted. For the beam-target double-spin…
Inclusive studies of nuclear photoabsorption have provided clear evidence of medium modifications in the properties of hadrons. However, the results have not been explained in a model independent way. A deeper understanding of the situation…
We show that ordinary and radiative muon capture impose stringent constraints on sterile neutrino properties. In particular, we consider a sterile neutrino with a mass between 40 to $80 {\rm MeV}$ that has a large mixing with the muon…