Polarization Observables $T$ and $F$ in the $\gamma p \to \pi^0 p$ Reaction at CLAS

Abstract

Pion photoproduction in the $\overrightarrow\gamma\overrightarrow p \to \pi^0 p$ reaction has been measured in the FROST experiment at the Thomas Jefferson National Accelerator Facility. In this experiment, circularly polarized photons with energies up to 3.082 GeV impinged on a transversely polarized frozen-spin target. Final-state protons were detected in the CEBAF Large Acceptance Spectrometer. Results of the polarization observables $T$ and $F$ have been extracted for $W$ from 1445 MeV to 2525 MeV. The data generally agree with predictions of present partial-wave analyses, but also show marked differences for higher $W$ ranges. By incorporating the present data into the databases, the SAID fits have been improved with relatively small $\chi^2$ and significant changes in the parameters of the $\Delta(1910)1/2^+$ and $N(2190)7/2^-$ have been found with the J\"uBo model.