Coherent $\rho$-meson photo production from CLAS

Coherent $\rho$ photoproduction from the deuteron has been studied at CLAS as a function of the photon energy and the 4-momentum transfer. Tagged photons with beam energies between 0.8 and 3.0 GeV were produced using the bremsstrahlung process at Hall B of Jefferson Lab, incident on a deuterium target, during the run period g10. The final state particles detected are an energetic deuteron and a pair of charged pions from the $\rho^0$ meson decay. These events were constrained to have zero missing mass, to ensure an exclusive reaction. Preliminary cross sections have been obtained from fits to the $\rho$ peak in the invariant mass spectrum of the $\pi^+\pi^-$ pair for bins in the 4-momentum transfer $t$ as a function of $E_\gamma$. These data are important to test models of hadronic scattering of $\rho$ mesons from the nucleon, as it is not possible to produce beams of $\rho$ mesons. In addition, this study is also important to understand the backgrounds in analyses of a possible $d^*$ dibaryon resonance that has the same final state.