6,863 research outputs found
Hamilton-Jacobi Theory in k-Symplectic Field Theories
In this paper we extend the geometric formalism of Hamilton-Jacobi theory for
Mechanics to the case of classical field theories in the k-symplectic
framework
Nonholonomic constraints in -symplectic Classical Field Theories
A -symplectic framework for classical field theories subject to
nonholonomic constraints is presented. If the constrained problem is regular
one can construct a projection operator such that the solutions of the
constrained problem are obtained by projecting the solutions of the free
problem. Symmetries for the nonholonomic system are introduced and we show that
for every such symmetry, there exist a nonholonomic momentum equation. The
proposed formalism permits to introduce in a simple way many tools of
nonholonomic mechanics to nonholonomic field theories.Comment: 27 page
Spectral analysis of Markarian 421 and Markarian 501 with HAWC
The Hight Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory monitors the
gamma-ray sky in the energy range from 100 GeV to 100 TeV and has detected two
very high energy (VHE) blazars: Markarian 421 (Mrk 421) and Markarian 501 (Mrk
501) in 1.5 years of observations. In this work, we present the spectral
analysis above 1 TeV of both sources using a maximum likelihood method and an
artificial neural network as an energy estimator. The main objectives are to
constrain the spectral curvature of Mrk 421 and Mrk 501 at 5 TeV using
the EBL models from Gilmore et al. (2012) and Franceschini et al. (2008).Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017),
Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution
A semi-infinite matrix analysis of the BFKL equation
The forward BFKL equation is discretised in virtuality space and it is shown
that the diffusion into infrared and ultraviolet momenta can be understood in
terms of a semi-infinite matrix. The square truncation of this matrix can be
exponentiated leading to asymptotic eigenstates sharing many features with the
BFKL gluon Green's function in the limit of large matrix size. This truncation
is closely related to a representation of the XXX Heisenberg spin chain with SL(2) invariance where the Hamiltonian acts on a
symmetric double copy of the harmonic oscillator. A simple modification of the
BFKL matrix suppressing the infrared modes generates evolution with energy
compatible with unitarity.Comment: Small changes, same conclusions, matching the published version in
EPJ
On the Multimomentum Bundles and the Legendre Maps in Field Theories
We study the geometrical background of the Hamiltonian formalism of
first-order Classical Field Theories. In particular, different proposals of
multimomentum bundles existing in the usual literature (including their
canonical structures) are analyzed and compared. The corresponding Legendre
maps are introduced. As a consequence, the definition of regular and
almost-regular Lagrangian systems is reviewed and extended from different but
equivalent ways.Comment: LaTeX file, 19 pages. Replaced with the published version. Minor
mistakes are correcte
Solitary Waves in Massive Nonlinear S^N-Sigma Models
The solitary waves of massive (1+1)-dimensional nonlinear S^N-sigma models
are unveiled. It is shown that the solitary waves in these systems are in
one-to-one correspondence with the separatrix trajectories in the repulsive
N-dimensional Neumann mechanical problem. There are topological (heteroclinic
trajectories) and non-topological (homoclinic trajectories) kinks. The
stability of some embedded sine-Gordon kinks is discussed by means of the
direct estimation of the spectra of the second-order fluctuation operators
around them, whereas the instability of other topological and non-topological
kinks is established applying the Morse index theorem
An Approach to Publish Spatial Data on the Web: The GeoLinked Data Case
In this paper we report on an ongoing process aimed at publishing hydrographical data on the Web with a Spanish GeoLinked Data Use Case. Moreover, we discuss the process we followed, and propose methodological guidelines for all the activities involved within the process
- …