1,020 research outputs found
HEADSS: HiErArchical Data Splitting and Stitching software for non-distributed clustering algorithms
On a stochastic partial differential equation with non-local diffusion
In this paper, we prove existence, uniqueness and regularity for a class of
stochastic partial differential equations with a fractional Laplacian driven by
a space-time white noise in dimension one. The equation we consider may also
include a reaction term
Dust detection by the wave instrument on STEREO: nanoparticles picked up by the solar wind?
The STEREO/WAVES instrument has detected a very large number of intense
voltage pulses. We suggest that these events are produced by impact ionisation
of nanoparticles striking the spacecraft at a velocity of the order of
magnitude of the solar wind speed. Nanoparticles, which are half-way between
micron-sized dust and atomic ions, have such a large charge-to-mass ratio that
the electric field induced by the solar wind magnetic field accelerates them
very efficiently. Since the voltage produced by dust impacts increases very
fast with speed, such nanoparticles produce signals as high as do much larger
grains of smaller speeds. The flux of 10-nm radius grains inferred in this way
is compatible with the interplanetary dust flux model. The present results may
represent the first detection of fast nanoparticles in interplanetary space
near Earth orbit.Comment: In press in Solar Physics, 13 pages, 5 figure
Axial vector current in an electromagnetic field and low-energy neutrino-photon interactions
An expression for the axial vector current in a strong, slowly varying
electromagnetic field is obtained. We apply this expression to the construction
of the effective action for low-energy neutrino-photon interactions.Comment: 6 pages, references updated, final version to appear in Phys. Rev.
The black hole final state
We propose that in quantum gravity one needs to impose a final state boundary
condition at black hole singularities. This resolves the apparent contradiction
between string theory and semiclassical arguments over whether black hole
evaporation is unitary.Comment: 17 pages, harvmac, 1 figure, v2: comment about interactions and
references adde
General Static Solutions of 2-dimensional Einstein-Dilaton-Maxwell-Scalar Theories
General static solutions of effectively 2-dimensional
Einstein-Dilaton-Maxwell-Scalar theories are obtained. Our model action
includes a class of 2-d dilaton gravity theories coupled with a gauge
field and a massless scalar field. Therefore it also describes the spherically
symmetric reduction of -dimensional Einstein-Scalar-Maxwell theories. The
properties of the analytic solutions are briefly discussed.Comment: 16 pages, Latex fil
Supersymmetry for Fermion Masses
It is proposed that supersymmetry (SUSY) maybe used to understand fermion
mass hierarchies. A family symmetry Z_{3L} is introduced, which is the cyclic
symmetry among the three generation SU(2) doublets. SUSY breaks at a high
energy scale ~ 10^{11} GeV. The electroweak energy scale ~ 100 GeV is
unnaturally small. No additional global symmetry, like the R-parity, is
imposed. The Yukawa couplings and R-parity violating couplings all take their
natural values which are about (10^0-10^{-2}). Under the family symmetry, only
the third generation charged fermions get their masses. This family symmetry is
broken in the soft SUSY breaking terms which result in a hierarchical pattern
of the fermion masses. It turns out that for the charged leptons, the tau mass
is from the Higgs vacuum expectation value (VEV) and the sneutrino VEVs, the
muon mass is due to the sneutrino VEVs, and the electron gains its mass due to
both Z_{3L} and SUSY breaking. The large neutrino mixing are produced with
neutralinos playing the partial role of right-handed neutrinos. |V_{e3}| which
is for nu_e-nu_{tau} mixing is expected to be about 0.1. For the quarks, the
third generation masses are from the Higgs VEVs, the second generation masses
are from quantum corrections, and the down quark mass due to the sneutrino
VEVs. It explains m_c/m_s, m_s/m_e, m_d > m_u and so on. Other aspects of the
model are discussed.Comment: 25 pages, 3 figures, revtex4; neutrino oscillation and many
discussions added, smallness of the electron mass due to supersymmetry
pointed out; v3: numerical errors correcte
Secondary Beam Monitors for the NuMI Facility at FNAL
The Neutrinos at the Main Injector (NuMI) facility is a conventional neutrino
beam which produces muon neutrinos by focusing a beam of mesons into a long
evacuated decay volume. We have built four arrays of ionization chambers to
monitor the position and intensity of the hadron and muon beams associated with
neutrino production at locations downstream of the decay volume. This article
describes the chambers' construction, calibration, and commissioning in the
beam.Comment: Accepted for publication in Nucl. Instr. Meth.
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