Measurement of the Transverse Target and Beam-Target Asymmetries in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi></mml:math>Meson Photoproduction at MAMI

Abstract

We present new data for the transverse target asymmetry $T$ and the very first data for the beam-target asymmetry $F$ in the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\rightarrow}\ensuremath{\eta}p$ reaction up to a center-of-mass energy of $W=1.9\text{ }\mathrm{GeV}$. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of $\ensuremath{\eta}$ meson photoproduction. The peculiar nodal structure observed in existing $T$ data close to threshold is not confirmed.