Description
Exclusive photoproduction of $\rho(770)$ vector mesons is studied using the H1 detector at HERA. A sample of about 700000 decays $\rho\to\pi^{+}\pi^{−}$ was collected in the years 2006-2007, using the H1 fast track trigger. It corresponds to an integrated luminosity of 1.3 pb${}^{−1}$. The sample is used to study cross-sections as a function of the invariant mass $m_{\pi\pi}$ of the decay pions, the photon-proton collision energy $W$ and the momentum transfer at the proton vertex $t$. The phase-space restrictions are $0.5< m_{\pi\pi}<1.3$ GeV, $20< W<80$ GeV and $\vert t\vert<1.5$ GeV${}^{2}$. Reactions where the proton stays intact are statistically separated from those where the proton dissociates to a low-mass hadronic system. The observed cross-section dependencies are parameterized using fits and are compared to expectations from phenomenological models.
