Determination of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>ω</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>Spin—Density-Matrix Elements in the Reaction<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:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mi>p</mml:mi><mml:mo>→</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mi>ω</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi>n</mml:mi></mml:math>

We report measurements of the ${\ensuremath{\omega}}^{0}$ spin-density matrix elements in the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\omega}}^{0}n$ at incident momenta of 3.65, 4.5, and 5.5 $\frac{\mathrm{GeV}}{c}$. In the Gottfried-Jackson frame the data exhibit nonzero values of ${\ensuremath{\rho}}_{00}$, indicating the presence of unnatural-parity exchange as well as a large value of ${\ensuremath{\rho}}_{11}+{\ensuremath{\rho}}_{1\ensuremath{-}1}$ which does not show a dip in the momentum transfer distribution. The unnatural-parity contribution decreases with respect to the natural-parity contribution as the momentum increases.