Photoproduction of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>With Plane Polarized 3-GeV Photons

Abstract

The cross section for photoproduction of ${\ensuremath{\pi}}^{0}$ mesons was measured at a photon energy of 3 GeV and squared four-momentum transfer ($t$) of -0.1 to -1.2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ using plane-polarized photons. The asymmetry was found to be consistent with +1.0 for $t$ values above -0.4 and below -1.1. For $\ensuremath{-}0.4&lt;~t&lt;~\ensuremath{-}1.0$ there is a dip in the asymmetry and at $t=\ensuremath{-}0.6$ it drops to 0.55 \ifmmode\pm\else\textpm\fi{} 0.15. This result precludes a simple Regge model with ${\ensuremath{\omega}}^{0}$ and $B$; a theoretical description requires Regge cuts or an ${\ensuremath{\omega}}^{\ensuremath{'}}$ exchange.