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

Abstract

Polarisation-dependent differential cross sections σ[superscript T] associated with the target asymmetry T have been measured for the reaction γ[→ over p]→pπ[superscript 0] with transverse target polarisation from π[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 σ[superscript T] have been used in combination with our previous measurements of the unpolarised cross section σ[superscript 0] and the beam asymmetry σ for a model-independent determination of S- and P-wave multipoles in the π[superscript 0] threshold region, which includes for the first time a direct determination of the imaginary part of the E[subscript 0+] multipole.