1,994 research outputs found
Non-Beiter ternary cyclotomic polynomials with an optimally large set of coefficients
Let l>=1 be an arbitrary odd integer and p,q and r primes. We show that there
exist infinitely many ternary cyclotomic polynomials \Phi_{pqr}(x) with
l^2+3l+5<= p<q<r such that the set of coefficients of each of them consists of
the p integers in the interval [-(p-l-2)/2,(p+l+2)/2]. It is known that no
larger coefficient range is possible. The Beiter conjecture states that the
cyclotomic coefficients a_{pqr}(k) of \Phi_{pqr} satisfy |a_{pqr}(k)|<= (p+1)/2
and thus the above family contradicts the Beiter conjecture. The two already
known families of ternary cyclotomic polynomials with an optimally large set of
coefficients (found by G. Bachman) satisfy the Beiter conjecture.Comment: 20 pages, 7 Table
Ternary cyclotomic polynomials having a large coefficient
Let denote the th cyclotomic polynomial. In 1968 Sister Marion
Beiter conjectured that , the coefficient of in ,
satisfies in case with primes (in this
case is said to be ternary). Since then several results towards
establishing her conjecture have been proved (for example ).
Here we show that, nevertheless, Beiter's conjecture is false for every . We also prove that given any there exist infinitely many
triples with consecutive primes such that
for .Comment: 19 pages, 6 tables, to appear in Crelle's Journal. Revised version
with many small change
Supersymmetric Drinfeld-Sokolov reduction
The Drinfeld-Sokolov construction of integrable hierarchies, as well as its
generalizations, may be extended to the case of loop superalgebras. A
sufficient condition on the algebraic data for the resulting hierarchy to be
invariant under supersymmetry transformation is given. The method used is a
construction of the hierarchies in superspace, where supersymmetry is manifest.
Several examples are discussed.Comment: 25 pages, LaTeX fil
N=2 KP and KdV hierarchies in extended superspace
We give the formulation in extended superspace of an supersymmetric KP
hierarchy using chirality preserving pseudo-differential operators. We obtain
two quadratic hamiltonian structures, which lead to different reductions of the
KP hierarchy. In particular we find two different hierarchies with the
classical super- algebra as a hamiltonian structure. The relation
with the formulation in superspace is carried out.Comment: 18 pages, LaTeX file, important reference adde
Extra energy coupling through subwavelength hole arrays via stochastic resonance
Interaction between metal surface waves and periodic geometry of
subwavelength structures is at the core of the recent but crucial renewal of
interest in plasmonics. One of the most intriguing points is the observation of
abnormal strong transmission through these periodic structures, which can
exceed by orders of magnitude the classical transmission given by the filling
factor of the plate. The actual paradigm is that this abnormal transmission
arises from the periodicity, and then that such high transmission should
disappear in random geometries. Here, we show that extra energy can be coupled
through the subwavelength structure by adding a controlled quantity of noise to
the position of the apertures. This result can be modelled in the statistical
framework of stochastic resonance. The evolution of the coupled energy with
respect to noise gives access to the extra energy coupled at the surface of the
subwavelength array.Comment: 12 page
Experimental evidence of percolation phase transition in surface plasmons generation
Carrying digital information in traditional copper wires is becoming a major
issue in electronic circuits. Optical connections such as fiber optics offers
unprecedented transfer capacity, but the mismatch between the optical
wavelength and the transistors size drastically reduces the coupling
efficiency. By merging the abilities of photonics and electronics, surface
plasmon photonics, or 'plasmonics' exhibits strong potential. Here, we propose
an original approach to fully understand the nature of surface electrons in
plasmonic systems, by experimentally demonstrating that surface plasmons can be
modeled as a phase of surface waves. First and second order phase transitions,
associated with percolation transitions, have been experimentally observed in
the building process of surface plasmons in lattice of subwavelength apertures.
Percolation theory provides a unified framework for surface plasmons
description
The Erd\H{o}s--Moser equation revisited using continued fractions
If the equation of the title has an integer solution with , then
. This was the current best result and proved using a
method due to L. Moser (1953). This approach cannot be improved to reach the
benchmark . Here we achieve by showing that
is a convergent of and making an extensive continued
fraction digits calculation of , with an appropriate integer.
This method is very different from that of Moser. Indeed, our result seems to
give one of very few instances where a large scale computation of a numerical
constant has an application.Comment: 17 page
- …