Muon--proton deep elastic scattering

We have measured muon-proton elastic scattering in the range $0.6<{q}^{2}<3.2$ (GeV/c)². We compared these data with the corresponding elastic electron-proton cross sections by forming the ratio $r\left(q^2\right)=\frac{G^2(\mu -p)}{G^2(e-p)}$, where $G\left(q^2\right)=\frac{G_M\left(q^2\right)}{\mu }$ is the form factor of the proton. By fitting $r\left(q^2\right)=N{(1+\frac{q^2}{{\Lambda }^2})}^{-2}$ we find N=1.043±0.080 and Λ⁻²=+0.064±0.038 (GeV/c)⁻². Combining our data with those of two previous μ-p elastic scattering experiments yields Λ⁻²=+0.051±0.024 (GeV/c)⁻² which is a much weaker limit on muon-electron universality than that obtained from μ-p inelastic scattering.