18,288 research outputs found

    Secondary Quantum Hamiltonian Reduction

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    Recently, it has been shown how to perform the quantum hamiltonian reduction in the case of general sl(2)sl(2) embeddings into Lie (super)algebras, and in the case of general osp(12)osp(1|2) embeddings into Lie superalgebras. In another development it has been shown that when HH and HH' are both subalgebras of a Lie algebra GG with HHH'\subset H, then classically the W(G,H)W(G,H) algebra can be obtained by performing a secondary hamiltonian reduction on W(G,H)W(G,H'). In this paper we show that the corresponding statement is true also for quantum hamiltonian reduction when the simple roots of HH' can be chosen as a subset of the simple roots of HH. As an application, we show that the quantum secondary reductions provide a natural framework to study and explain the linearization of the WW algebras, as well as a great number of new realizations of WW algebras.Comment: 33 pages, LATEX. Final version, including proof of conjecture. Accepted for publication in Comm. Math. Phy

    High-harmonic generation from arbitrarily oriented diatomic molecules including nuclear motion and field-free alignment

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    We present a theoretical model of high-harmonic generation from diatomic molecules. The theory includes effects of alignment as well as nuclear motion and is used to predict results for N2_2, O2_2, H2_2 and D2_2. The results show that the alignment dependence of high-harmonics is governed by the symmetry of the highest occupied molecular orbital and that the inclusion of the nuclear motion in the theoretical description generally reduces the intensity of the harmonic radiation. We compare our model with experimental results on N2_2 and O2_2, and obtain very good agreement.Comment: 12 pages, 8 figures, 2 tables; legends revised on Figs. 1,3,4,6 and