Thermoelastic Noise and Homogeneous Thermal Noise in Finite Sized Gravitational-Wave Test Masses

An analysis is given of thermoelastic noise (thermal noise due to thermoelastic dissipation) in finite sized test masses of laser interferometer gravitational-wave detectors. Finite-size effects increase the thermoelastic noise by a modest amount; for example, for the sapphire test masses tentatively planned for LIGO-II and plausible beam-spot radii, the increase is less than or of order 10 per cent. As a side issue, errors are pointed out in the currently used formulas for conventional, homogeneous thermal noise (noise associated with dissipation which is homogeneous and described by an imaginary part of the Young's modulus) in finite sized test masses. Correction of these errors increases the homogeneous thermal noise by less than or of order 5 per cent for LIGO-II-type configurations.Comment: 10 pages and 3 figures; RevTeX; submitted to Physical Review

Observation of Muon Neutrino Disappearance with the MINOS Detectors in the NuMI Neutrino Beam

This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current ν_μ interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27×10^(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336±14 events. The data are consistent with ν_μ disappearance via oscillations with Δm_(32)^2|=2.74_(-0.26)^(+0.44)×10^(-3)  eV^2 and sin^2(2θ_(23))>0.87 (68% C.L.)

First observations of separated atmospheric ν_μ and ν̅ _μ events in the MINOS detector

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of ν_μ and ν̅ _μ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving R^(data)_(up/down/R^(MC)_(up/down) = 0:62^(+0.19)_(0:14)(stat.) ± 0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field ν_μ and ν̅ _μ interactions are separated. The ratio of ν̅ _μ to ν_μ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R^(data)_(ν_μ/ν̅ _μ) / R^(MC)_(ν_μ/ν̅ _μ) = 0.96^(+0:38)_(0.27)(stat.) ± 0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for ν_μ and ν̅ _μ

Lattice Heavy Quark Effective Theory and the Isgur-Wise function

We compute the Isgur-Wise function using heavy quark effective theory formulated on the lattice. The non-relativistic kinetic energy term of the heavy quark is included to the action as well as terms remaining in the infinite quark mass limit. The classical velocity of the heavy quark is renormalized on the lattice and we determine the renormalized velocity non-perturbatively using the energy-momentum dispersion relation. The slope parameter of the Isgur-Wise function at zero recoil is obtained at $\beta=6.0$ on a $24^3\times 48$ lattice for three values of $m_{Q}$.Comment: 14 pages of A4 format and 8 figures in one uuencoded postscript fil

Quantum Fluctuations of the Gravitational Field and Propagation of Light: a Heuristic Approach

Quantum gravity is quite elusive at the experimental level; thus a lot of interest has been raised by recent searches for quantum gravity effects in the propagation of light from distant sources, like gamma ray bursters and active galactic nuclei, and also in earth-based interferometers, like those used for gravitational wave detection. Here we describe a simple heuristic picture of the quantum fluctuations of the gravitational field that we have proposed recently, and show how to use it to estimate quantum gravity effects in interferometers.Comment: LaTeX2e, 8 pages, 2 eps figures: Talk presented at QED2000, 2nd Workshop on Frontier Tests of Quantum Electrodynamics and Physics of the Vacuum; included in conference proceeding

Searches for New Quarks and Leptons Produced in Z-Boson Decay

We have searched for events with new-particle topologies in 390 hadronic Z decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower limits of 40.7 GeV/c^2 for the top-quark mass, 42.0 GeV/c^2 for the mass of a fourth-generation charge - 1/3 quark, and 41.3 GeV/c^2 for the mass of an unstable Dirac neutral lepton

b-quark decay in the collinear approximation

The semileptonic decay of a b-quark, b--> c l nu, is considered in the relativistic limit where the decay products are approximately collinear. Analytic results for the double differential lepton energy distributions are given for finite charm-quark mass. Their use for the fast simulation of isolated lepton backgrounds from heavy quark decays is discussed.Comment: 7 pages, 1 figure, submitted to Phys.Rev.

Observation of the Radiative Decay D^(*+) → D^+y

We have observed a signal for the decay D^(*+)→D^+γ at a significance of 4 standard deviations. From the measured branching ratio B(D^(*+)→D^+γ)/B(D^(*+)→D^+π^0) = 0.055±0.014±0.010 we find B(D^(*+)→D^+γ) = 0.017±0.004±0.003, where the first uncertainty is statistical and the second is systematic. We also report the highest precision determination of the remaining D^(*+) branching fractions

Measurement of the total cross section for e^+e^-→hadrons at √s=10.52 GeV

Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of R≡σ(e^+e^-→hadrons)/σ(e^+e^-→μ^+μ^-)=3.56±0.01±0.07 at √s=10.52 GeV. This implies a value for the strong coupling constant of α_s(10.52 GeV)=0.20±0.01±0.06, or α_s(MZ)=0.13±0.005±0.03

Search for Inclusive b → sl^+l^-

We have searched for the effective flavor changing neutral-current decays b→sl^+l^- using an inclusive method. We set upper limits on the branching ratios B(b→se^+e^-)<5.7×10^(-5), B(b→sμ^+μ^-)<5.8×10^(-5), and B(b→se^±μ^∓)<2.2×10^(-5) [at 90% confidence level (C.L.)]. Combing the dielectron and dimuon decay modes we find B(b→sl^+l^-)<4.2×10^(-5) (at 90% C.L.)