Evidence for top quark production in [ital [bar p]p] collisions at [radical][ital s] =1. 8 TeV

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of [ital [bar p]p] collisions at [radical][ital s] =1.8 TeV with an integrated luminosity of 19.3 pb[sup [minus]1]. We find 12 events consistent with either two [ital W] bosons, or a [ital W] boson and at least one [ital 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 [ital t[bar t]] production. Under this assumption, constrained fits to individual events yield a top quark mass of 174[plus minus]10[sub [minus]12][sup +13] GeV/[ital c][sup 2]. The [ital t[bar t]] production cross section is measured to be 13.9[sub [minus]4.8][sup +6.1] pb.