Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHigher-derivative harmonic oscillators: stability of classical dynamics and adiabatic invariants
80
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The status of classical stability in higher-derivative systems is still subject to discussions. In this note, we argue that, contrary to general belief, many higher-derivative systems are classically stable. The main tool to see this property are Nekhoroshevs estimates relying on the action-angle formulation of classical mechanics. The latter formulation can be reached provided the Hamiltonian is separable, which is the case for higher-derivative harmonic oscillators. The Pais-Uhlenbeck oscillators appear to be the only type of higher-derivative harmonic oscillator with stable classical dynamics. A wide class of interaction potentials can even be added that preserve classical stability. Adiabatic invariants are built in the case of a Pais-Uhlenbeck oscillator slowly changing in time; it is shown indeed that the dynamical stability is not jeopardised by the time-dependent perturbation.
rate research
Read More
We present the derivation of conserved tensors associated to higher-order symmetries in the higher derivative Maxwell Abelian gauge field theories. In our model, the wave operator of the higher derived theory is a $n$-th order polynomial expressed in terms of the usual Maxwell operator. Any symmetry of the primary wave operator gives rise to a collection of independent higher-order symmetries of the field equations which thus leads to a series of independent conserved quantities of derived system. In particular, by the extension of Noethers theorem, the spacetime translation invariance of the Maxwell primary operator results in the series of conserved second-rank tensors which includes the standard canonical energy-momentum tensors. Although this canonical energy is unbounded from below, by introducing a set of parameters, the other conserved tensors in the series can be bounded which ensure the stability of the higher derivative dynamics. In addition, with the aid of auxiliary fields, we successfully obtain the relations between the roots decomposition of characteristic polynomial of the wave operator and the conserved energy-momentum tensors within the context of another equivalent lower-order representation. Under the certain conditions, the 00-component of the linear combination of these conserved quantities is bounded and by this reason, the original derived theory is considered stable. Finally, as an instructive example, we discuss the third-order derived system and analyze extensively the stabilities in different cases of roots decomposition.
We present exact classical solutions of the higher-derivative theory that describes the dynamics of the position modulus of a probe brane within a five-dimensional bulk. The solutions can be interpreted as static or time-dependent throats connecting two parallel branes. In the nonrelativistic limit the brane action is reduced to that of the Galileon theory. We derive exact solutions for the Galileon, which reproduce correctly the shape of the throats at large distances, but fail to do so for their central part. We also determine the parameter range for which the Vainshtein mechanism is reproduced within the brane theory.
We study the Harmonic and Dirac Oscillator problem extended to a three-dimensional noncom- mutative space where the noncommutativity is induced by a shift of the dynamical variables with generators of SL(2;R) in a unitary irreducible representation. The Hilbert space gets the structure of a direct product with the representation space as a factor, where there exist operators which realize the algebra of Lorentz transformations. The spectrum of these models are considered in perturbation theory, both for small and large noncommutativity parameters, finding no constraints between coordinates and momenta noncom- mutativity parameters. Since the representation space of the unitary irreducible representations SL(2;R) can be realized in terms of spaces of square-integrable functions, we conclude that these models are equivalent to quantum mechanical models of particles living in a space with an additional compact dimension. PACS: 03.65.-w; 11.30.Cp; 02.40.Gh
Within the framework of six-dimensional ${cal N}=(1,0)$ conformal supergravity, we introduce new off-shell multiplets ${cal O}{}^{*}(n)$, where $n=3,4,dots,$ and use them to construct higher-rank extensions of the linear multiplet action. The ${cal O}{}^{*}(n)$ multiplets may be viewed as being dual to well-known superconformal ${cal O}(n)$ multiplets. We provide prepotential formulations for the ${cal O}(n)$ and ${cal O}{}^{*}(n)$ multiplets coupled to conformal supergravity. For every ${cal O}{}^{*}(n)$ multiplet, we construct a higher derivative invariant which is superconformal on arbitrary superconformally flat backgrounds. We also show how our results can be used to construct new higher derivative actions in supergravity.
The role played by Deligne-Beilinson cohomology in establishing the relation between Chern-Simons theory and link invariants in dimensions higher than three is investigated. Deligne-Beilinson cohomology classes provide a natural abelian Chern-Simons action, non trivial only in dimensions $4l+3$, whose parameter $k$ is quantized. The generalized Wilson $(2l+1)$-loops are observables of the theory and their charges are quantized. The Chern-Simons action is then used to compute invariants for links of $(2l+1)$-loops, first on closed $(4l+3)$-manifolds through a novel geometric computation, then on $mathbb{R}^{4l+3}$ through an unconventional field theoretic computation.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
