9,531 research outputs found
Handedness asymmetry of spiral galaxies with z<0.3 shows cosmic parity violation and a dipole axis
A dataset of 126,501 spiral galaxies taken from Sloan Digital Sky Survey was
used to analyze the large-scale galaxy handedness in different regions of the
local universe. The analysis was automated by using a transformation of the
galaxy images to their radial intensity plots, which allows automatic analysis
of the galaxy spin and can therefore be used to analyze a large galaxy dataset.
The results show that the local universe (z<0.3) is not isotropic in terms of
galaxy spin, with probability P<5.8*10^-6 of such asymmetry to occur by chance.
The handedness asymmetries exhibit an approximate cosine dependence, and the
most likely dipole axis was found at RA=132, DEC=32 with 1 sigma error range of
107 to 179 degrees for the RA. The probability of such axis to occur by chance
is P<1.95*10^-5 . The amplitude of the handedness asymmetry reported in this
paper is generally in agreement with Longo, but the statistical significance is
improved by a factor of 40, and the direction of the axis disagrees somewhat.Comment: 8 pages, 6 figures. Accepted for publication in Physics Letters
A Gauge-Fixing Action for Lattice Gauge Theories
We present a lattice gauge-fixing action with the following
properties: (a) is proportional to the trace of , plus irrelevant terms of dimension six and higher; (b)
has a unique absolute minimum at . Noting that the
gauge-fixed action is not BRST invariant on the lattice, we discuss some
important aspects of the phase diagram.Comment: 13 pages, Latex, improved presentation, no change in result
On the Complexity of Bandit Linear Optimization
We study the attainable regret for online linear optimization problems with
bandit feedback, where unlike the full-information setting, the player can only
observe its own loss rather than the full loss vector. We show that the price
of bandit information in this setting can be as large as , disproving the
well-known conjecture that the regret for bandit linear optimization is at most
times the full-information regret. Surprisingly, this is shown using
"trivial" modifications of standard domains, which have no effect in the
full-information setting. This and other results we present highlight some
interesting differences between full-information and bandit learning, which
were not considered in previous literature
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