Internal labelling operators and contractions of Lie algebras
نویسنده
چکیده
We analyze under which conditions the missing label problem associated to a reduction chain s ⊂ s of (simple) Lie algebras can be completely solved by means of an Inönü-Wigner contraction g naturally related to the embedding. This provides a new interpretation of the missing label operators in terms of the Casimir operators of the contracted algebra, and shows that the available labeling operators are not completely equivalent. Further, the procedure is used to obtain upper bounds for the number of invariants of affine Lie algebras arising as contractions of semisimple algebras. PACS numbers: 02.20Sv, 02.20Qs
منابع مشابه
Determinantal formulae for the Casimir operators of inhomogeneous Lie algebras
Contractions of Lie algebras are combined with the classical matrix method of Gel’fand to obtain matrix formulae for the Casimir operators of inhomogeneous Lie algebras. The method is presented for the inhomogeneous pseudounitary Lie algebras Iu(p, q). This procedure is extended to contractions of Iu(p, q) isomorphic to an extension by a derivation of the inhomogeneous special pseudo-unitary Li...
متن کاملNew determinantal formulae for the Casimir operators of inhomogeneous pseudo-unitary Lie algebras and their Inönü-Wigner contractions
For the inhomogeneous pseudo-unitary Lie algebras Iu(p, q) a determinantal method to compute the Casimir operators is given, independently of the traditional analysis of the enveloping algebra. This procedure is extended to contractions of Iu(p, q) isomorphic to an extension by a derivation of the inhomogeneous special pseudo-unitary Lie algebras Isu(p − 1, q), providing an alternative analytic...
متن کاملVirtual copies of semisimple Lie algebras in enveloping algebras of semidirect products and Casimir operators
Given a semidirect product g = s ⊎ r of semisimple Lie algebras s and solvable algebras r, we construct polynomial operators in the enveloping algebra U(g) of g that commute with r and transform like the generators of s, up to a functional factor that turns out to be a Casimir operator of r. Such operators are said to generate a virtual copy of s in U(g), and allow to compute the Casimir operat...
متن کاملContractions of Low-Dimensional Lie Algebras
Theoretical background of continuous contractions of finite-dimensional Lie algebras is rigorously formulated and developed. In particular, known necessary criteria of contractions are collected and new criteria are proposed. A number of requisite invariant and semiinvariant quantities are calculated for wide classes of Lie algebras including all low-dimensional Lie algebras. An algorithm that ...
متن کاملRealization of locally extended affine Lie algebras of type $A_1$
Locally extended affine Lie algebras were introduced by Morita and Yoshii in [J. Algebra 301(1) (2006), 59-81] as a natural generalization of extended affine Lie algebras. After that, various generalizations of these Lie algebras have been investigated by others. It is known that a locally extended affine Lie algebra can be recovered from its centerless core, i.e., the ideal generated by weight...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008