Conservation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>s</mml:mi></mml:math>-Channel Helicity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>ρ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>Photoproduction

An analysis was made of the decay angular distribution of rho mesons produced via $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\rho}}^{0}$ by linearly polarized photons at 2.8 and 4.7 GeV. The reaction proceeds almost completely through natural-parity exchange, the contribution from unnatural-parity exchange for momentum transfers $|t|&lt;1$ Ge${\mathrm{V}}^{2}$ being (3.1\ifmmode\pm\else\textpm\fi{}2.2)% at 2.8 GeV and (-1.1\ifmmode\pm\else\textpm\fi{}1.9)% at 4.7 GeV. The behavior of the density-matrix elements shows that the rho-production mechanism conserves $s$-channel c.m. system helicity for $|t|&lt;0.4$ Ge${\mathrm{V}}^{2}$.