Evidence for top quark production in<i>p</i>¯<i>p</i>collisions at √<i>s</i>=1.8 TeV

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =1.8 TeV with an integrated luminosity of 19.3 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$. We find 12 events consistent with either two W bosons, or a W boson and at least one b jet. The probability that the measured yield is consistent with the background is 0.26%. Though the statistics are too limited to establish firmly the existence of the top quark, a natural interpretation of the excess is that it is due to tt\ifmmode\bar\else\textasciimacron\fi{} production. Under this assumption, constrained fits to individual events yield a top quark mass of 174\ifmmode\pm\else\textpm\fi{}${10}_{\mathrm{\ensuremath{-}}12}^{+13}$ GeV/${\mathit{c}}^{2}$. The tt\ifmmode\bar\else\textasciimacron\fi{} production cross section is measured to be 13.${9}_{\mathrm{\ensuremath{-}}4.8}^{+6.1}$ pb.