ATLAS

Abstract:

A study of the particle multiplicity between jets with large rapidity separation has been performed using the D0 detector at the Fermilab Tevatron pp^¯ Collider operating at √s = 1.8 TeV. A significant excess of low-multiplicity events is observed above the expectation for color-exchange processes. The measured fractional excess is 1.07±0.10(stat)^+0.25−0.13(syst)%, which is consistent with a strongly interacting color-singlet (colorless) exchange process and cannot be explained by electroweak exchange alone. A lower limit of 0.80% (95% C.L.) is obtained on the fraction of dijet events with color-singlet exchange, independent of the rapidity gap survival probability. © 1996 The American Physical Society.

Abstract:

The lifetimes of the B- and B−0 mesons are measured using the partially reconstructed semileptonic decays B−→D1-v−X, where D is either a D0 or D*+ meson. The data were collected by the CDF detector at the Fermilab Tevatron collider during 1992-1993 and correspond to 19.3 pb−1 of p−p collisions at s = 1.8 TeV. We measure the decay length distributions and find the lifetimes to be τ(B−) = 1.56±0.13±0.06 ps and τ(B−0) = 1.54±0.08±0.06 ps, and the ratio of lifetimes to be τ(B−)/τ(B−0) = 1.01±0.11±0.02, where the first uncertainties are statistical and the second are systematic. © 1996 The American Physical Society.

Abstract:

A measurement of the mass of the W boson is presented based on a sample of 5982 W → eν decays observed in pp^¯ collisions at √s = 1.8 TeV with the D0 detector during the 1992-1993 run. From a fit to the transverse mass spectrum, combined with measurements of the Z boson mass, the W boson mass is measured to be MW = 80.350 ± 0.140(stat) ± 0.165(syst) ± 0.160(scale) GeV/c². © 1996 The American Physical Society.

Abstract:

We report on a measurement of the branching fraction of the Cabibbo-suppressed decay B⁺u→J/ψπ⁺, where J/ψJ/ψμ⁺μ^-. The data were collected by the Collider Detector at Fermilab during 1992–1995 and correspond to an integrated luminosity of 110pb^-1 in pp collisions at √s=1.8TeV. A signal of 28⁺¹⁰-9 events is observed and we determine the ratio of branching fractions B(B⁺u→J/ψπ⁺)/B(B⁺u→J/ψK⁺) to be [5.0^+1.9-1.7(stat)±0.1(syst)]%. Using the world average value for B(B⁺u→J/ψπ⁺), we calculate the branching fraction B(B⁺u→J/ψπ⁺) to be (5.0^+2.1-1.9)×10^-5. We also search for the decay B⁺c→J/ψπ⁺ and report a 95% confidence level limit on σ(B⁺c)B⁺c→J/ψπ⁺/σ(B⁺u)B(B⁺u→J/ψK⁺) as a function of the B+c lifetime. © 1996 The American Physical Society.