Limits on extra dimensions and new particle production in the exclusive photon and missing energy signature in pp collisions at square root [s]=1.8 TeV.
Phys Rev Lett 89:28 Pt 1 (2002) 281801
Abstract:
The exclusive gammaE(T) signal has a small standard model cross section and is thus a channel sensitive to new physics. This signature is predicted by models with a superlight gravitino or with large extra spatial dimensions. We search for such signals at the Collider Detector at Fermilab, using 87 pb(-1) of data at square root [s]=1.8 TeV, and extract 95% C.L. limits on these processes. A limit of 221 GeV is set on the scale |F|(1/2) in supersymmetric models. For 4, 6, and 8 extra dimensions, model-dependent limits on the fundamental mass scale M(D) of 0.55, 0.58, and 0.60 TeV, respectively, are found. We also specify a "pseudo-model-independent" method of comparing the results to theoretical predictions.Comparison of the isolated direct photon cross sections in pp̄ collisions at √s = 1.8 TeV and √s = 0.63 TeV
Physical Review D 65:11 (2002)
Abstract:
We have measured the cross sections d2σ/d P Tdη) for production of isolated direct photons in pp̄ collisions at two different center-of-mass energies, 1.8 TeV and 0.63 TeV, using the Collider Detector at Fermilab. The normalization of both data sets agrees with the predictions of quantum chromodynamics for a photon transverse momentum (PT) of 25 GeV/c, but the shapes versus photon PT do not. These shape differences lead to a significant disagreement in the ratio of cross sections in the scaling variable xT(≡ 2PT/√s). This disagreement in the xT ratio is difficult to explain with conventional theoretical uncertainties such as scale dependence and parton distribution parametrizations. © 2002 The American Physical Society.Branching ratio measurements of exclusive B+ decays to charmonium with the collider detector at fermilab
Physical Review D - Particles, Fields, Gravitation and Cosmology 66:5 (2002) 520051-520057
Abstract:
We report on measurements of the branching ratios of the decays B+→Xcl0(1P)K+ and B+ →J/ψK+π+π-, where Xcl0(1P)→J/ψγ and J/ψ→μ+μ- in pp collisions at √s= 1.8 TeV. Using a data sample from an integrated luminosity of 110 pb-1 collected by the Collider Detector at Fermilab we measure the branching ratios to be BR(B+→Xcl0(1P) K+)=15.5±5.4(stat)±1.5(syst)±1.3(br)× 10-4 and BR(B+ →J/ψK+π+π-)=6.9 ±1.8(stat)±1.1(syst)±0.4(br)×10-4 where (br) is due to the finite precision on BR(B-→J/ψK+), BR(Xcl0(1P)→J/ψγ)is used to normalize the signal yield, and (syst) encompasses all other systematic uncertainties.Γ production and polarization in pp̄ collisions at √s = 1.8 TeV
Physical Review Letters 88:16 (2002) 1618021-1618026
Abstract:
The differential cross sections for the γ(1S), γ(2S), and γ(3S) states and the γ(1S) polarization were measured. Fits of nonrelativistic quantumchromodynamics (NRQCD) matrix elements could describe the cross sections. The polarization systematic uncertainties were also indicated. The polarization measurement was made by fitting the shape of the uncorrected data.Diffractive dijet production at sqrt[s] = 630 and 1800 GeV at the Fermilab Tevatron.
Phys Rev Lett 88:15 (2002) 151802