43,942 research outputs found
Additional Acceleration of Protons and Energetic Neutrino Production in a Filamentary Jet of the Blazar Markarian 501
Blazars have been regarded as one of the most powerful sources of the highest
energy cosmic rays and also their byproducts, neutrinos. Provided that a
magnetized filamentary system is established in a blazar jet as well, we could
apply the mechanism of multi-stage diffusive shock acceleration to a feasible
TeV emitter, Mrk 501 to evaluate the achievable maximum energy of protons.
Taking conceivable energy restriction into account systematically, it seems
adequate to say that EeV-protons are produced at this site by our present
model. We also estimate neutrino fluxes generated by these accelerated protons
and discuss the detectability based on an updated kilometre-scale telescope
such as IceCube.Comment: 17 pages, 3 Postscript figure
Sutured Floer homology, sutured TQFT and non-commutative QFT
We define a "sutured topological quantum field theory", motivated by the
study of sutured Floer homology of product 3-manifolds, and contact elements.
We study a rich algebraic structure of suture elements in sutured TQFT, showing
that it corresponds to contact elements in sutured Floer homology. We use this
approach to make computations of contact elements in sutured Floer homology
over of sutured manifolds where is
finite. This generalises previous results of the author over
coefficients. Our approach elaborates upon the quantum field theoretic aspects
of sutured Floer homology, building a non-commutative Fock space, together with
a bilinear form deriving from a certain combinatorial partial order; we show
that the sutured TQFT of discs is isomorphic to this Fock space.Comment: v.2: 49 pages, 13 figures. Improved and expanded exposition, some
minor corrections. Sections on torsion, annuli, and tori moved to a separate
pape
Exact Asymptotics for the Random Coding Error Probability
Error probabilities of random codes for memoryless channels are considered in
this paper. In the area of communication systems, admissible error probability
is very small and it is sometimes more important to discuss the relative gap
between the achievable error probability and its bound than to discuss the
absolute gap. Scarlett et al. derived a good upper bound of a random coding
union bound based on the technique of saddlepoint approximation but it is not
proved that the relative gap of their bound converges to zero. This paper
derives a new bound on the achievable error probability in this viewpoint for a
class of memoryless channels. The derived bound is strictly smaller than that
by Scarlett et al. and its relative gap with the random coding error
probability (not a union bound) vanishes as the block length increases for a
fixed coding rate.Comment: Full version of the paper in ISIT2015 with some corrections and
refinement
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