Dijet Mass Spectrum and a Search for Quark Compositeness in $\overline{\mathit{p}}\mathit{p}$ Collisions at $\surd \mathit{s}=1.8\mathrm{}\mathrm{TeV}$

Using the D0 detector at the 1.8 TeV $\overline{p}p$ Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region $|{\eta }_{\mathrm{jet}}|<1.0\mathrm{}$ for dijet masses greater than $200\mathrm{GeV}{/c}^2$. We have also measured the ratio of spectra $\sigma (|{\eta }_{\mathrm{jet}}|<0.5\mathrm{})/\sigma (0.5<\mathrm{}|{\eta }_{\mathrm{jet}}|<1.0\mathrm{})$. The order ${\alpha }_s^3$ quantum chromodynamics predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale $<2.4\mathrm{}\mathrm{TeV}$ at the $95\%$ confidence level.