Photoproduction of phi(1020) mesons on the proton at large momentum transfer

We report the first measurement of the differential cross section on $\phi$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections $\frac{d\sigma}{dt}$ for the initial photon energy from...

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 Accelerator Facility. In this kinematic range the integrated luminosity was about 20 pb$^{-1}$. The reaction was isolated by detecting the $\pi^+$ and proton in CLAS, and reconstructing the $\pi^-$ via the missing-mass technique. Moments of the di-p...

We present predictions for the exclusive photoproduction of $\Phi$-meson on Proton at large tranfer, where we use a quark-diquark structure model for the proton. Extrapolation from our results to lower tranfers is comparable in magnitude with available data in that range. This may support the diquark model in its ability to provide, for that process, an appropriate link between diffractive physics at low transfer and the standard semi-perturbative approach of hard exclusive p...

The production of $\phi$ mesons in the reaction $e^{+}p \rightarrow e^{+} \phi p$ ($\phi \rightarrow K^{+}K^{-}$), for $7 < Q^2 < 25$ GeV$^2$ and for virtual photon-proton centre of mass energies ($W$) in the range 42-134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar $Q^2$, the results show that the $\gamma^*p \rightarrow \phid p$ cross section rises strongly with $W$. This behaviour is similar to that previously found for...

We calculate the differential cross section and single-polarization observables for the reaction $\gamma p \to \Phi p$ within perturbative QCD, treating the proton as a quark-diquark system. The phenomenological couplings of gauge bosons to (spatially extended) diquarks and the quark-diquark distribution amplitude of the proton are adopted from previous investigations of baryon form factors and two-photon processes. Going beyond leading order, we take into account hadron-mass...

The first measurement of $\phi(1020)$ meson production in fixed-target $p$Ne collisions at $\sqrt{s_{NN}}=68.5$ GeV is presented. The $\phi(1020)$ mesons are reconstructed in their $K^{+}K^{-}$ decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of $21.7 \pm 1.4$ nb$^{-1}$, collected by the LHCb detector at CERN. The $\phi(1020)$ production cross-section in the centre-of-mass rapidity range of $-1.8<y^*<0$ a...

We report the total and differential cross sections for $J/\psi$ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold at 8.2~GeV up to 11.44~GeV and over the full kinematic range of momentum transfer squared, $t$. Such coverage facilitates the extrapolation of the differential cross sections to the forward ($t = 0$) point beyond the physical region. The forward cross section is used by many theoretical models and plays an im...

Photoproduction cross sections are reported for the reaction $\gamma p\to p\eta$ using energy-tagged photons and the CLAS spectrometer at Jefferson Laboratory. The $\eta$ mesons are detected in their dominant charged decay mode, $\eta\to \pi^+\pi^-\pi^0$, and results on differential cross sections are presented for incident photon energies between 1.2 and 4.7 GeV. These new $\eta$ photoproduction data are consistent with earlier CLAS results but extend the energy range beyond...

We report the first measurement of the photoproduction cross section of the $\phi$ meson in its neutral decay mode in the reaction $\gamma p \to p\phi(K_SK_L)$. The experiment was performed with a tagged photon beam of energy $1.6 \le E_\gamma \le 3.6$ GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The $p \phi$ final state is identified via reconstruction of $K_S$ in the invariant mass of two oppositely...

Diffractive photoproduction of vector mesons, gamma p --> V Y, where Y is a proton-dissociative system, has been measured in ep interactions with the ZEUS detector at HERA using an integrated luminosity of 25 pb^-1. The differential cross section, ds/dt, is presented for -t<12 GeV^2, where t is the square of the four-momentum transferred to the vector meson. The data span the range in photon-proton centre-of-mass energy, W, from 80 GeV to 120 GeV. The t distributions are well...