1,932 research outputs found
Antineutrino Physics at MINOS
We present two new measurements of antineutrino properties based on a data sample corresponding to 3.2×10^(20) protons-on-target, exploiting MINOS' unique ability to distinguish positive and negative muons and thus separate charged current neutrino and antineutrino interactions event-by-event. The first measurement takes advantage of the 6% antineutrino component of the NuMI neutrino beam to measure antineutrino oscillations between the near and far detectors. We observe 42 events at the far detector with an expectation of 58.3±7.6(stat.)±3.6(syst.) assuming CPT-conserving oscillations, excluding (5.0<Δm(overbar)^2<81)×10^(−3)eV^2 at 90% confidence at maximal mixing. We also present a search for neutrino-antineutrino transitions ν_μ → ν(overbar)_μ, which would result in an excess of antineutrino events in the Far Detector relative to the rate expected from the intrinsic antineutrino component in the neutrino beam. We observe no excess and set a limit of 0.026 on the transition probability at 90% confidence
B+ and Ds+ Decay Constants from Belle and Babar
The Belle and Babar experiments have measured the branching fractions for B+
-> tau+ nu and Ds+ -> mu+ nu decays. From these measurements one can extract
the B+ and Ds+ decay constants, which can be compared to lattice QCD
calculations. For the Ds+ decay constant, there is currently a 2.1 sigma
difference between the calculated value and the measured value.Comment: 10 pages, 8 figures, 1 table, contribution to the Tenth Conference on
the Intersections of Particle and Nuclear Physics (CIPANP 2009), San Diego,
Californi
The measurement of alpha from the B-factories
Significant progress toward measuring the CKM angle alpha has been made by
the B-factories over the past decade. This work has culminated in a constraint
on alpha with a precision of less than 4 degrees.Comment: Proceedings of the Tenth Conference on the Intersections of Particle
and Nuclear Physics, San Diego, California, May 2009 (4 pages
QCD Effects in Cosmology
The cosmological evolution in the radiation dominated regimen is usually
computed by assuming an ideal relativistic thermal bath. In this note, we
discuss the deviation from the non-interaction assumption. In either the
standard model (SM) and the minimal supersymmetric standard model (MSSM), the
main contribution comes from the strong interaction. An understanding of these
effects are important for precision measurements and for the evolution of
scalar modes, where the commented corrections constitute the main source of the
dynamics.Comment: 4 pages, 2 figures. Contributed to CIPANP 2009: Tenth Conference on
the Intersections of Particle and Nuclear Physics, May 26-31, 2009, San
Diego, Californi
Measurements of the CKM angle
In this report we summarize the most recent results of measurements of the
angle of the Unitarity Triangle.Comment: 4 pages proceedings for CIPANP'09 conferenc
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The effect of surface heterogeneity on cloud absorption estimates
This study presents a systematic and quantitative analysis of the effect of inhomogeneous surface albedo on shortwave cloud absorption estimates. We used 3D radiative transfer modeling over a checkerboard surface albedo to calculate cloud absorption. We have found that accounting for surface heterogeneity enhances cloud absorption. However, the enhancement is not sufficient to explain the reported difference between measured and modeled cloud absorption
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Spectrally-invariant behavior of zenith radiance around cloud edges simulated by radiative transfer
In a previous paper, we discovered a surprising spectrally-invariant relationship in shortwave spectrometer observations taken by the Atmospheric Radiation Measurement (ARM) program. The relationship suggests that the shortwave spectrum near cloud edges can be determined by a linear combination of zenith radiance spectra of the cloudy and clear regions. Here, using radiative transfer simulations, we study the sensitivity of this relationship to the properties of aerosols and clouds, to the underlying surface type, and to the finite field-of-view (FOV) of the spectrometer. Overall, the relationship is mostly sensitive to cloud properties and has little sensitivity to other factors. At visible wavelengths, the relationship primarily depends on cloud optical depth regardless of cloud phase function, thermodynamic phase and drop size. At water-absorbing wavelengths, the slope of the relationship depends primarily on cloud optical depth; the intercept, by contrast, depends primarily on cloud absorbing and scattering properties, suggesting a new retrieval method for cloud drop effective radius. These results suggest that the spectrally-invariant relationship can be used to infer cloud properties near cloud edges even with insufficient or no knowledge about spectral surface albedo and aerosol properties
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