Threshold [pi superscript 0] photoproduction on transverse polarised protons at MAMI

Abstract

Polarisation-dependent differential cross sections [sigma][subscript Tau] associated with the target asymmetry [Tau] have been measured for the reaction [gamma arrow over p] [right arrow] p[pi superscript 0] with transverse target polarisation from [pi superscript 0] threshold to photon energies of 190 MeV. The data were obtained using a frozen-spin butanol target with the Crystal Ball / TAPS detector set-up and the Glasgow photon tagging system at the Mainz Microtron MAMI. Results for [sigma][subscript Tau] have been used in combination with our previous measurements of the unpolarised cross section [sigma subscript 0] and the beam asymmetry Σ for a model-independent determination of S- and P-wave multipoles in the [pi superscript 0] threshold region, which includes for the first time a direct determination of the imaginary part of the E[subscript 0+] multipole.