18,376 research outputs found
Matrix models without scaling limit
In the context of hermitean one--matrix models we show that the emergence of
the NLS hierarchy and of its reduction, the KdV hierarchy, is an exact result
of the lattice characterizing the matrix model. Said otherwise, we are not
obliged to take a continuum limit to find these hierarchies. We interpret this
result as an indication of the topological nature of them. We discuss the
topological field theories associated with both and discuss the connection with
topological field theories coupled to topological gravity already studied in
the literature.Comment: Latex, SISSA-ISAS 161/92/E
The (N,M)-th KdV hierarchy and the associated W algebra
We discuss a differential integrable hierarchy, which we call the (N, M)MW_N$ algebra. We show
that there exist M distinct reductions of the (N, M)--th KdV hierarchy, which
are obtained by imposing suitable second class constraints. The most drastic
reduction corresponds to the (N+M)--th KdV hierarchy. Correspondingly the W(N,
M) algebra is reduced to the W_{N+M} algebra. We study in detail the
dispersionless limit of this hierarchy and the relevant reductions.Comment: 40 pages, LaTeX, SISSA-171/93/EP, BONN-HE-46/93, AS-IPT-49/9
The generalized KP hierarchy
We propose one possible generalization of the KP hierarchy, which possesses
multi bi--hamiltonian structures, and can be viewed as several KP hierarchies
coupled together.Comment: 12
MeV oxygen ion implantation induced compositional intermixing in AlAs/GaAs superlattices
We present in this letter an investigation of compositional intermixing in AlAs/GaAs superlattices induced by 2 MeV oxygen ion implantation. The results are compared with implantation at 500 keV. In addition to Al intermixing in the direct lattice damage region by nuclear collision spikes, as is normally present in low-energy ion implantation, Al interdiffusion has also been found to take place in the subsurface region where MeV ion induced electronic spike damage dominates and a uniform strain field builds up due to defect generation and diffusion. Uniform compositional intermixing of the superlattices results after subsequent thermal annealing when Al interdiffusion is stimulated through recovery of the implantation-induced lattice strain field, the reconstruction and the redistribution of lattice defects, and annealing of lattice damage
Localized Asymmetric Atomic Matter Waves in Two-Component Bose-Einstein Condensates Coupled with Two Photon Microwave Field
We investigate localized atomic matter waves in two-component Bose-Einstein
condensates coupled by the two photon microwave field. Interestingly, the
oscillations of localized atomic matter waves will gradually decay and finally
become non-oscillating behavior even if existing coupling field. In particular,
atom numbers occupied in two different hyperfine spin states will appear
asymmetric occupations after some time evolution.Comment: 4 pages, 4 figure
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