Rubin-LSST

Abstract:

High resolution spectra of an early B-type star associated with the H II region detected by de Geus et al. (1993) are analysed using LTE model atmosphere techniques to derive stellar atmospheric parameters and a chemical composition. A distance to the star of 8.2 kpc is estimated, placing it near the edge of the galactic disk and closer than the kinematic distance of 20 kpc to the H II region, calculated by de Geus et al. A differential line by line abundance analysis with respect to the spectroscopic standard τ Sco indicates a significant metal depletion, with elements down on average by -0.5 dex.

Abstract:

We present a measurement of the forward-backward charge asymmetry of the process pp¯ → Z0/γ + X, Z0/γ → e+e− at Mee > MZ using 110 pb−1 of data at √ s = 1.8 TeV collected at the Collider Detector at Fermilab. The measured charge asymmetries are 0.43 ± 0.10 in the invariant mass region Mee > 105 GeV/c2, and 0.070 ± 0.016 in the region 75 < Mee < 105 GeV/c2. These results are consistent with the standard model values of 0.528 ± 0.009 and 0.052 ± 0.002, respectively. © 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:

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.

Abstract:

We measure the mass of the B0s meson by reconstructing the decay chain B0s→J/ψφ, J/ψ→µ+µ-, and φ→K+K-. The data are obtained from 19.3 pb-1 of integrated luminosity of pp collisions at √s=1.8 TeV using the Collider Detector at Fermilab. A sample of 80 000 inclusive J/ψ→µ+µ- events is used to study systematic biases in track reconstruction and to calibrate the momentum scale. We reconstruct the kinematically similar decays B+→J/ψK+ and B0→J/ψK*0 to study the mass measurement technique used for the B0s meson. Based on the observation of 32 ± 6 candidates, the mass of the B0s meson is measured to be 5369.9 ± 2.3 ± 1.3 MeV/c2 and the mass difference between B0s and the average mass of B+ and B0 is determined to be 89.7 ± 2.7 ± 1.2 MeV/c2. © 1996 The American Physical Society.