169,963 research outputs found
New analytic results for electroweak baryon number violation
Real-time anomalous fermion number violation has been investigated for
massless chiral fermions in spherically symmetric SU(2) Yang-Mills gauge field
backgrounds which can be weakly dissipative or even nondissipative. Restricting
consideration to spherically symmetric fermion fields, a relation has been
found between the spectral flow of the Dirac Hamiltonian and two
characteristics of the background gauge field. This new result may be relevant
to electroweak baryon number violation in the early universe.Comment: 7 pages with jhep3.cls, based on a talk at the International
Europhysics Conference on High Energy Physics, Budapest, 200
Exact Moderate Deviation Asymptotics in Streaming Data Transmission
In this paper, a streaming transmission setup is considered where an encoder
observes a new message in the beginning of each block and a decoder
sequentially decodes each message after a delay of blocks. In this
streaming setup, the fundamental interplay between the coding rate, the error
probability, and the blocklength in the moderate deviations regime is studied.
For output symmetric channels, the moderate deviations constant is shown to
improve over the block coding or non-streaming setup by exactly a factor of
for a certain range of moderate deviations scalings. For the converse proof, a
more powerful decoder to which some extra information is fedforward is assumed.
The error probability is bounded first for an auxiliary channel and this result
is translated back to the original channel by using a newly developed
change-of-measure lemma, where the speed of decay of the remainder term in the
exponent is carefully characterized. For the achievability proof, a known
coding technique that involves a joint encoding and decoding of fresh and past
messages is applied with some manipulations in the error analysis.Comment: 23 pages, 1 figure, 1 table, Submitted to IEEE Transactions on
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Specific heat of single crystal MgB_2: a two-band superconductor with two different anisotropies
Heat-capacity measurements of a 39 microgramm MgB_2 single crystal in fields
up to 14 T and below 3 K allow the determination of the low-temperature linear
term of the specific heat, its field dependence and its anisotropy. Our results
are compatible with two-band superconductivity, the band carrying the small gap
being isotropic, that carrying the large gap having an anisotropy of ~ 5. Three
different upper critical fields are thus needed to describe the superconducting
state of MgB2.Comment: 4 pages, 4 figures - V2: Bibliography updated and some typo
corrected. One reference added - V3: version accepted for publication in PRL,
changes made in the tex
Surface Effects of Flame Spreading over Igniting Composite Solid Propellants Constituents
Flame spreading over surface of igniting composite solid propellant constituent
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