Cross sections for the reaction $\mathrm{ep}\to \mathrm{ep}{X}^0$, measured by detecting both the scattered electron and the proton, are given for missing masses $m_x$ between 0 and $1 \frac{\mathrm{GeV}}{c^2}$. Enhancements are observed at $m_x=0\mathrm{}$ and in the region of the $\rho$ meson at $q^2=0.1\mathrm{} \mathrm{and} 0.5 {\left(\frac{\mathrm{GeV}}{c}\right)}^2$. The electroproduction of all states with $m_x$ between 0.7 and $0.83 \frac{\mathrm{GeV}}{c^2}$ varies like $e^{-7.5t}$ for $q^2=0.1\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$, similar to missing-mass photoproduction, but for $q^2=0.5\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$ it varies like $e^{-3.5t}$. In this mass region the resolution tail of the large bremsstrahlung peak at $m_x=0\mathrm{}$ is small.

• Received 8 December 1971

DOI:https://doi.org/10.1103/PhysRevLett.28.516