11,363 research outputs found
Correlations of RMT Characteristic Polynomials and Integrability: Hermitean Matrices
Integrable theory is formulated for correlation functions of characteristic
polynomials associated with invariant non-Gaussian ensembles of Hermitean
random matrices. By embedding the correlation functions of interest into a more
general theory of tau-functions, we (i) identify a zoo of hierarchical
relations satisfied by tau-functions in an abstract infinite-dimensional space,
and (ii) present a technology to translate these relations into hierarchically
structured nonlinear differential equations describing the correlation
functions of characteristic polynomials in the physical, spectral space.
Implications of this formalism for fermionic, bosonic, and supersymmetric
variations of zero-dimensional replica field theories are discussed at length.
A particular emphasis is placed on the phenomenon of fermionic-bosonic
factorisation of random-matrix-theory correlation functions.Comment: 62 pages, 1 table, published version (typos corrected
Abundance of unknots in various models of polymer loops
A veritable zoo of different knots is seen in the ensemble of looped polymer
chains, whether created computationally or observed in vitro. At short loop
lengths, the spectrum of knots is dominated by the trivial knot (unknot). The
fractional abundance of this topological state in the ensemble of all
conformations of the loop of segments follows a decaying exponential form,
, where marks the crossover from a mostly unknotted
(ie topologically simple) to a mostly knotted (ie topologically complex)
ensemble. In the present work we use computational simulation to look closer
into the variation of for a variety of polymer models. Among models
examined, is smallest (about 240) for the model with all segments of the
same length, it is somewhat larger (305) for Gaussian distributed segments, and
can be very large (up to many thousands) when the segment length distribution
has a fat power law tail.Comment: 13 pages, 6 color figure
Radio Galaxy Zoo: Cosmological Alignment of Radio Sources
We study the mutual alignment of radio sources within two surveys, FIRST and
TGSS. This is done by producing two position angle catalogues containing the
preferential directions of respectively and extended
sources distributed over more than and square degrees. The
identification of the sources in the FIRST sample was performed in advance by
volunteers of the Radio Galaxy Zoo project, while for the TGSS sample it is the
result of an automated process presented here. After taking into account
systematic effects, marginal evidence of a local alignment on scales smaller
than is found in the FIRST sample. The probability of this happening
by chance is found to be less than per cent. Further study suggests that on
scales up to the alignment is maximal. For one third of the sources,
the Radio Galaxy Zoo volunteers identified an optical counterpart. Assuming a
flat CDM cosmology with , we
convert the maximum angular scale on which alignment is seen into a physical
scale in the range Mpc . This result supports recent
evidence reported by Taylor and Jagannathan of radio jet alignment in the
deg ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The
TGSS sample is found to be too sparsely populated to manifest a similar signal
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