628 research outputs found
Six types of functions of the Lie groups O(5) and G(2)
New families of -functions are described in the context of the compact
simple Lie groups O(5) and G(2). These functions of two real variables
generalize the common exponential functions and for each group, only one family
is currently found in the literature. All the families are fully characterized,
their most important properties are described, namely their continuous and
discrete orthogonalities and decompositions of their products.Comment: 25 pages, 13 figure
Exact Solutions of a (2+1)-Dimensional Nonlinear Klein-Gordon Equation
The purpose of this paper is to present a class of particular solutions of a
C(2,1) conformally invariant nonlinear Klein-Gordon equation by symmetry
reduction. Using the subgroups of similitude group reduced ordinary
differential equations of second order and their solutions by a singularity
analysis are classified. In particular, it has been shown that whenever they
have the Painlev\'e property, they can be transformed to standard forms by
Moebius transformations of dependent variable and arbitrary smooth
transformations of independent variable whose solutions, depending on the
values of parameters, are expressible in terms of either elementary functions
or Jacobi elliptic functions.Comment: 16 pages, no figures, revised versio
Orthogonal Decomposition of Some Affine Lie Algebras in Terms of their Heisenberg Subalgebras
In the present note we suggest an affinization of a theorem by Kostrikin
et.al. about the decomposition of some complex simple Lie algebras
into the algebraic sum of pairwise orthogonal Cartan subalgebras. We point out
that the untwisted affine Kac-Moody algebras of types ( prime,
), can be decomposed into
the algebraic sum of pairwise or\-tho\-go\-nal Heisenberg subalgebras. The
and cases are discussed in great detail. Some possible
applications of such decompositions are also discussed.Comment: 16 pages, LaTeX, no figure
Recursion relations and branching rules for simple Lie algebras
The branching rules between simple Lie algebras and its regular (maximal)
simple subalgebras are studied. Two types of recursion relations for anomalous
relative multiplicities are obtained. One of them is proved to be the
factorized version of the other. The factorization property is based on the
existence of the set of weights specific for each injection. The
structure of is easily deduced from the correspondence between the
root systems of algebra and subalgebra. The recursion relations thus obtained
give rise to simple and effective algorithm for branching rules. The details
are exposed by performing the explicit decomposition procedure for injection.Comment: 15p.,LaTe
Maximal Abelian Subgroups of the Isometry and Conformal Groups of Euclidean and Minkowski Spaces
The maximal Abelian subalgebras of the Euclidean e(p,0) and pseudoeuclidean
e(p,1)Lie algebras are classified into conjugacy classes under the action of
the corresponding Lie groups E(p,0) and E(p,1), and also under the conformal
groups O(p+1,1) and O(p+1,2), respectively. The results are presented in terms
of decomposition theorems. For e(p,0) orthogonally indecomposable MASAs exist
only for p=1 and p=2. For e(p,1), on the other hand, orthogonally
indecomposable MASAs exist for all values of p. The results are used to
construct new coordinate systems in which wave equations and Hamilton-Jacobi
equations allow the separation of variables.Comment: 31 pages, Latex (+ latexsym
Extended calibration range for prompt photon emission in ion beam irradiation
Monitoring the dose delivered during proton and carbon ion therapy is still a
matter of research. Among the possible solutions, several exploit the
measurement of the single photon emission from nuclear decays induced by the
irradiation. To fully characterize such emission the detectors need
development, since the energy spectrum spans the range above the MeV that is
not traditionally used in medical applications. On the other hand, a deeper
understanding of the reactions involving gamma production is needed in order to
improve the physic models of Monte Carlo codes, relevant for an accurate
prediction of the prompt-gamma energy spectrum.This paper describes a
calibration technique tailored for the range of energy of interest and
reanalyzes the data of the interaction of a 80MeV/u fully stripped carbon ion
beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation
with the appropriate calibration and resolution a significant improvement in
the agreement between data and simulation is reported.Comment: 4 pages, 7 figures, Submitted to JINS
Solvable Lie algebras with triangular nilradicals
All finite-dimensional indecomposable solvable Lie algebras , having
the triangular algebra T(n) as their nilradical, are constructed. The number of
nonnilpotent elements in satisfies and the
dimension of the Lie algebra is
Quantum transfer matrices for discrete and continuous quasi-exactly solvable problems
We clarify the algebraic structure of continuous and discrete quasi-exactly
solvable spectral problems by embedding them into the framework of the quantum
inverse scattering method. The quasi-exactly solvable hamiltonians in one
dimension are identified with traces of quantum monodromy matrices for specific
integrable systems with non-periodic boundary conditions. Applications to the
Azbel-Hofstadter problem are outlined.Comment: 15 pages, standard LaTe
Measurement of charged particle yields from therapeutic beams in view of the design of an innovative hadrontherapy dose monitor
Particle Therapy (PT) is an emerging technique, which makes use of charged particles to efficiently cure different kinds of solid tumors. The high precision in the hadrons dose deposition requires an accurate monitoring to prevent the risk of under-dosage of the cancer region or of over-dosage of healthy tissues. Monitoring techniques are currently being developed and are based on the detection of particles produced by the beam interaction into the target, in particular: charged particles, result of target and/or projectile fragmentation, prompt photons coming from nucleus de-excitation and back-to-back γ s, produced in the positron annihilation from β + emitters created in the beam interaction with the target. It has been showed that the hadron beam dose release peak can be spatially correlated with the emission pattern of these secondary particles. Here we report about secondary particles production (charged fragments and prompt γ s) performed at different beam and energies that have a particular relevance for PT applications: 12C beam of 80 MeV/u at LNS, 12C beam 220 MeV/u at GSI, and 12C, 4He, 16O beams with energy in the 50–300 MeV/u range at HIT. Finally, a project for a multimodal dose-monitor device exploiting the prompt photons and charged particles emission will be presented
Realizations of Real Low-Dimensional Lie Algebras
Using a new powerful technique based on the notion of megaideal, we construct
a complete set of inequivalent realizations of real Lie algebras of dimension
no greater than four in vector fields on a space of an arbitrary (finite)
number of variables. Our classification amends and essentially generalizes
earlier works on the subject.
Known results on classification of low-dimensional real Lie algebras, their
automorphisms, differentiations, ideals, subalgebras and realizations are
reviewed.Comment: LaTeX2e, 39 pages. Essentially exetended version. Misprints in
Appendix are correcte
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