Search for. lambda. p states in the baryon-exchange reaction pp. --> lambda. pK/sup +/ at 11. 75 GeV/c

We have obtained 1400 events of the baryon-exchange reaction $\mathrm{pp}\ensuremath{\rightarrow}\ensuremath{\Lambda}p{K}^{+}$ using the ANL Zero Gradient Synchrotron 11.75-GeV/c polarized proton beam and the effective-mass spectrometer. A search for enhancements in the $\ensuremath{\Lambda}p$ mass spectrum has been made. No enhancements are observed; in particular, the narrow $\ensuremath{\Lambda}p$ enhancement at 2.13 GeV seen in ${K}^{\ensuremath{-}}d\ensuremath{\rightarrow}\ensuremath{\Lambda}p{\ensuremath{\pi}}^{\ensuremath{-}}$ is not observed. We establish limits on the production of narrow states of \ensuremath{\sim} 10 nb. Also, 100000 events of the forward reaction $\mathrm{pp}\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{+}p$ were examined and no narrow $\ensuremath{\Lambda}p$ enhancements are seen.