8,406 research outputs found
A lower bound to the spectral threshold in curved tubes
We consider the Laplacian in curved tubes of arbitrary cross-section rotating
together with the Frenet frame along curves in Euclidean spaces of arbitrary
dimension, subject to Dirichlet boundary conditions on the cylindrical surface
and Neumann conditions at the ends of the tube. We prove that the spectral
threshold of the Laplacian is estimated from below by the lowest eigenvalue of
the Dirichlet Laplacian in a torus determined by the geometry of the tube.Comment: LaTeX, 13 pages; to appear in R. Soc. Lond. Proc. Ser. A Math. Phys.
Eng. Sc
On the behavior of clamped plates under large compression
We determine the asymptotic behavior of eigenvalues of clamped plates under large compression by relating this problem to eigenvalues of the Laplacian with Robin boundary conditions. Using the method of fundamental solutions, we then carry out a numerical study of the extremal domains for the first eigenvalue, from which we see that these depend on the value of the compression, and start developing a boundary structure as this parameter is increased. The corresponding number of nodal domains of the first eigenfunction of the extremal domain also increases with the compression.This work was partially supported by the Funda ̧c ̃ao para a Ciˆencia e a Tecnologia(Portugal) through the program “Investigador FCT” with reference IF/00177/2013 and the projectExtremal spectral quantities and related problems(PTDC/MAT-CAL/4334/2014).info:eu-repo/semantics/publishedVersio
Extreme Value Theory for Piecewise Contracting Maps with Randomly Applied Stochastic Perturbations
We consider globally invertible and piecewise contracting maps in higher
dimensions and we perturb them with a particular kind of noise introduced by
Lasota and Mackey. We got random transformations which are given by a
stationary process: in this framework we develop an extreme value theory for a
few classes of observables and we show how to get the (usual) limiting
distributions together with an extremal index depending on the strength of the
noise.Comment: 16 pages. arXiv admin note: text overlap with arXiv:1407.041
Phenomenology of the Little Higgs model with X-Parity
In the popular littlest Higgs model, T-parity can be broken by
Wess-Zumino-Witten (WZW) terms induced by a strongly coupled UV completion. On
the other hand, certain models with multiple scalar multiplets (called moose
models) permit the implementation of an exchange symmetry (X-parity) such that
it is not broken by the WZW terms. Here we present a concrete and realistic
construction of such a model. The little Higgs model with X-Parity is a
concrete and realistic implementation of this idea. In this contribution, the
properties of the model are reviewed and the collider phenomenology is
discussed in some detail. We also present new results on the decay properties
and LHC signatures of the light triplet scalars that are predicted by this
model.Comment: 12 pages, to appear in in the proceedings of the International
Workshop on Beyond the Standard Model Physics and LHC Signatures (BSM-LHC)
and of the 17th International Conference on Supersymmetry and the Unification
of Fundamental Interactions (SUSY09), Boston, USA, 2-4 and 5-10 Jun 200
Strong evidences for a nonextensive behavior of the rotation period in Open Clusters
Time-dependent nonextensivity in a stellar astrophysical scenario combines
nonextensive entropic indices derived from the modified Kawaler's
parametrization, and , obtained from rotational velocity distribution. These
's are related through a heuristic single relation given by , where is the cluster age. In a nonextensive
scenario, these indices are quantities that measure the degree of
nonextensivity present in the system. Recent studies reveal that the index
is correlated to the formation rate of high-energy tails present in the
distribution of rotation velocity. On the other hand, the index is
determined by the stellar rotation-age relationship. This depends on the
magnetic field configuration through the expression , where
and denote the saturation level of the star magnetic field and its
topology, respectively. In the present study, we show that the connection
is also consistent with 548 rotation period data for single
main-sequence stars in 11 Open Clusters aged less than 1 Gyr. The value of
2.5 from our unsaturated model shows that the mean magnetic field
topology of these stars is slightly more complex than a purely radial field.
Our results also suggest that stellar rotational braking behavior affects the
degree of anti-correlation between and cluster age . Finally, we suggest
that stellar magnetic braking can be scaled by the entropic index .Comment: 6 pages and 2 figures, accepted to EPL on October 17, 201
A Little Higgs Model with Exact Dark Matter Parity
Based on a recent idea by Krohn and Yavin, we construct a little Higgs model
with an internal parity that is not broken by anomalous Wess-Zumino-Witten
terms. The model is a modification of the "minimal moose" models by
Arkani-Hamed et al. and Cheng and Low. The new parity prevents large
corrections to oblique electroweak parameters and leads to a viable dark matter
candidate. It is shown how the complete Standard Model particle content,
including quarks and leptons together with their Yukawa couplings, can be
implemented. Successful electroweak symmetry breaking and consistency with
electroweak precision constraints is achieved for natural paramters choices. A
rich spectrum of new particles is predicted at the TeV scale, some of which
have sizable production cross sections and striking decay signatures at the
LHC.Comment: 25 pp. LaTeX; v2: improved discussion of precision constraints and
references added; v3: summary of model structure added at beginning of sect.
2, version published in JHEP; v4: small correction in Fig.5; v5: correction
to Fig.
Consequences of T-parity breaking in the Littlest Higgs model
In this paper we consider the effects of the T-parity violating anomalous
Wess-Zumino-Witten-Term in the Littlest Higgs model. Apart from tree level
processes, the loop induced decays of the heavy mirror particles into light
standard model fermions lead to a new and rich phenomenology in particular at
breaking scales f below 1 TeV. Various processes are calculated and their
signatures at present and future colliders are discussed. As a byproduct we
find an alternative production mechanism for the Higgs boson.Comment: 30 page
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