T. Chikamatsu

Charge asymmetry in [ital W]-boson decays produced in [ital p[bar p]] collisions at [radical][ital s]= 1. 8 TeV

Charge asymmetry has been measured using 19 039 [ital W] decays recorded by the Collider Detector at Fermilab during the 1992--93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of [ital d] and [ital u] quark distributions to [ital x][lt]0.01 at [ital Q][sup 2][approx][ital M][sup 2][sub [ital W]], where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts, and Stirling are favored over the sets most recently produced by the CTEQ Collaboration. The [ital W] asymmetry data provide stronger constraints on [ital d]/[ital u] ratio than the recent measurements of [ital F][sub 2][sup [mu][ital n]]/[ital F][sub 2][sup [mu][ital p]], which are limited by uncertainties originating from deuteron corrections.

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.

Measurement of the ratio sigma B(W-->e nu )/ sigma B(Z0-->e+e-) in p-barp collisions at sqrt s =1.8 TeV.

We present a measurement of the ratio [sigma][ital B]([ital W][r arrow][ital ev])/[sigma][ital B]([ital Z][sup 0][r arrow][ital e][sup +][ital e][sup [minus]]) in [ital [bar p]p] collisions at [radical][ital s] =1.8 TeV. The data represent an integrated luminosity of 21.7 pb[sup [minus]1] from the 1992--1993 run of the Collider Detector at Fermilab. We find [sigma][ital B]([ital W][r arrow][ital eV])/[sigma][ital B]([ital Z][sup 0][r arrow][ital e][sup +][ital e][sup [minus]])=10.90[plus minus]0.32(stat)[plus minus]0.29(sys t). From this value, we extract a value for the [ital W] width, [Gamma]([ital W])=2.064[plus minus]0.061(stat)[plus minus]0.059(syst) GeV, and the branching ratio, [Gamma]([ital W][r arrow][ital eV])/[Gamma]([ital W])=0.1094[plus minus]0.0033(stat)[plus minus]0.0031(syst), and we set a decay-mode-independent limit on the top quark mass [ital m][sub top][gt]62 GeV/[ital c][sup 2] at the 95% C.L.

Measurement of the ratio [sigma][ital B]([ital W][r arrow][ital e][nu])/[sigma][ital B]([ital Z][sup 0][r arrow][ital e][sup +][ital e][sup [minus]]) in [ital [bar p]p] collisions at [radical][ital s] =1. 8 TeV

We present a measurement of the ratio [sigma][ital B]([ital W][r arrow][ital ev])/[sigma][ital B]([ital Z][sup 0][r arrow][ital e][sup +][ital e][sup [minus]]) in [ital [bar p]p] collisions at [radical][ital s] =1.8 TeV. The data represent an integrated luminosity of 21.7 pb[sup [minus]1] from the 1992--1993 run of the Collider Detector at Fermilab. We find [sigma][ital B]([ital W][r arrow][ital eV])/[sigma][ital B]([ital Z][sup 0][r arrow][ital e][sup +][ital e][sup [minus]])=10.90[plus minus]0.32(stat)[plus minus]0.29(sys t). From this value, we extract a value for the [ital W] width, [Gamma]([ital W])=2.064[plus minus]0.061(stat)[plus minus]0.059(syst) GeV, and the branching ratio, [Gamma]([ital W][r arrow][ital eV])/[Gamma]([ital W])=0.1094[plus minus]0.0033(stat)[plus minus]0.0031(syst), and we set a decay-mode-independent limit on the top quark mass [ital m][sub top][gt]62 GeV/[ital c][sup 2] at the 95% C.L.