Search for lepton flavor violating decays of a heavy neutral particle in p(p)over-bar collisions at root s=1.8 TeV

We report on a search for a high mass, narrow width particle that decays directly to emu, etau, or mutau. We use approximately 110 pb(-1) of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions

Search for the supersymmetric partner of the top quark in dilepton events from p(p)over-bar collisions at root s=1.8 TeV

We have searched for the supersymmetric partner of the top quark (stop) in 107 pb^{-1} of p-pbar collisions at \sqrt{s}= 1.8 TeV collected by the Collider Detector at Fermilab (CDF). Within the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM) each of the pair-produced stops is assumed to decay into a lepton, bottom quark and supersymmetric neutrino. Such a scenario would give rise to events with two leptons, two hadronic jets, and a substantial imbalance of transverse energy. No evidence of such a stop signal has been found. We calculate a 95% confidence level (C.L.) upper limit on the stop production cross section, which excludes stop masses in the region (80<m_{\stop}<135 GeV/c^2) in the mass plane of stop versus sneutrino.Comment: 7 pages, 5 figures. Submitted to Physical Review Letter

Central pseudorapidity gaps in events with a leading antiproton at the Fermilab tevatron (p)over-barp collider

We report a measurement of the fraction of events with a large pseudorapidity gap Deltaeta within the pseudorapidity region available to the proton dissociation products X in (p) over bar +p-->(p) over bar +X. For a final state (p) over bar of fractional momentum loss xi((p) over bar) and 4-momentum transfer squared t((p) over bar) within 0.063 is found to be 0.246+/-0.001 (stat)+/-0.042 (syst) [0.184+/-0.001 (stat)+/-0.043 (syst)]. Our results are compared with gap fractions measured in minimum bias (p) over barp collisions and with theoretical expectations

Search for a W(') boson decaying to a top and bottom quark pair in 1.8 TeV p(p)over-bar collisions

We report the results of a search for a W(') boson produced in p (p) over bar collisions at a center-of-mass energy of 1.8 TeV using a 106 pb(-1) data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W(') boson decaying to a top and bottom quark pair. In a model where this boson would mediate interactions involving a massive right-handed neutrino (nu(R)) and have standard model strength couplings, we use these data to exclude a W(') boson with mass between 225 and 536 GeV/c(2) at 95\% confidence level for M(W)(')>M(nuR) and between 225 and 566 GeV/c(2) at 95\% confidence level for M(W)(')<M(nuR)

Observation of New Charmless Decays of Bottom Hadrons

We search for new charmless decays of neutral b hadrons to pairs of charged hadrons, using 1 fb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. We report the first observation of the B-s(0)-> K-pi(+) decay and measure B(B-s(0)-> K-pi(+))=(5.0 +/- 0.7(stat)+/- 0.8(syst))x10(-6). We also report the first observation of charmless b-baryon decays, and measure B(Lambda(0)(b)-> p pi(-))=(3.5 +/- 0.6(stat)+/- 0.9(syst))x10(-6) and B(Lambda(0)(b)-> pK(-))=(5.6 +/- 0.8(stat)+/- 1.5(syst))x10(-6). No evidence is found for other modes, and we set the limit B(B-s(0)->pi(+)pi(-))< 1.2x10(-6) at 90\% C.L

Momentum distribution of charged particles in jets in dijet events in p(p)over-bar collisions at root s=1.8 TeV and comparisons to perturbative QCD predictions

Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600 GeV/c(2). Events were produced at the Fermilab Tevatron in p (p) over bar collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Q(eff) and found a value of 230+/-40 MeV. The theoretical prediction of E(jet)sin theta(c) scaling, where theta(c) is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r=N-partons(g-jet)/N-partons(q-jet)=1.9+/-0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, K-LPHD(charged)=N-hadrons(charged)/N-partons=0.56+/-0.10

Search for associated production of Upsilon and vector boson in p(p)over-bar collisions at root(s)over-bar=1.8 TeV

We present a search for associated production of the Y(1S) and a vector boson in 83 pb(-1) of p (p) over bar collisions at roots=1.8 TeV collected by the CDF experiment in 1994-1995. We find no evidence of the searched signal in the data, and set upper limits to the production cross sections

PRODUCTION OF CHI-CHARMONIUM VIA 300-GEV/C PION AND PROTON INTERACTIONS ON A LITHIUM TARGET

We present a measurement and comparison of the chi(c1) and chi(c2) production cross sections determined from interactions of 300-GeV/c pi+/- and p with a Li target. We find chi(c1)/chi(c2) production ratios of 0.52(+0.57/-0.27) and 0.08(+0.25/-0.15) from reactions induced by pi+/- and p, respectively

Search for a W(') boson decaying to a top and bottom quark pair in 1.8 TeV p(p)over-bar collisions

We report the results of a search for a W(') boson produced in p (p) over bar collisions at a center-of-mass energy of 1.8 TeV using a 106 pb(-1) data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W(') boson decaying to a top and bottom quark pair. In a model where this boson would mediate interactions involving a massive right-handed neutrino (nu(R)) and have standard model strength couplings, we use these data to exclude a W(') boson with mass between 225 and 536 GeV/c(2) at 95% confidence level for M(W)(')>M(nuR) and between 225 and 566 GeV/c(2) at 95% confidence level for M(W)(')<M(nuR)

Observation of the Omega_b and Measurement of the Properties of the Xi-_b and Omega-_b Baryons

We report the observation of the bottom, doubly-strange Omega-_b through the decay chain Omega-_b --> J/psi Omega-, where J/psi --> mu+ mu-, Omega- --> Lambda K-, and Lambda --> p pi++, using 4.2 fb-1 of data from p anti-p collisions at s**(1/2) =1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0 x 10-8, or 5.5 Gaussian standard deviations. The Omega-_b mass is measured to be 6054.4 +/- 6.8(stat.) +/- 0.9(syst.) MeV/c2. The lifetime of the Omega-_b baryon is measured to be 1.13+0.53_-0.40(stat.) +/- 0.02(syst.) ps. In addition, for the Xi-_b baryon we measure a mass of 5790.9 +/- 2.6(stat.) +/- 0.8(syst.) MeV/c2 and a lifetime of 1.56+0.27_-0.25(stat.) +/- 0.02(syst.) ps. Under the assumption that the Xi-_b and Omega-_b are produced with similar kinematic distributions t the Lambda0(b) baryon, we find sigma(Xi-_b) B(Xi-_b --> J/psi Xi-)/sigma (Lambda0(b) B(Lambda0(b) --> J/psi Lambda) 0.167{+0.037}_{-0.025}(stat.) and sigma(Omega-_b) B(Omega-_b --> J/psi Omega-/Sigma(Lambda0(b)) B(Lambda0(b) --> J/psi Lambda) 0.045{+0.017}_{-0.012}(stat.) +/- 0.004(syst.) for baryons produced with transverse momentum in the range of 6-20 GeV/c