284 research outputs found
Interaction of instantons in a gauge theory forcing their identical orientation
A gauge theory model in which there exists a specific interaction between
instantons is considered. An effective action describing this interaction
possesses a minimum when the instantons have identical orientation. The
considered interaction might provide a phase transition into the state where
instantons have a preferred orientation. This phase of the gauge-field theory
is important because it can give the description of gravity in the framework of
the gauge theory.Comment: 8 pages, Revte
Weak Coupling Chambers in N=2 BPS Quiver Theory
Using recent results on BPS quiver theory, we develop a group theoretical
method to describe the quiver mutations encoding the quantum mechanical duality
relating the spectra of distinct quivers. We illustrate the method by computing
the BPS spectrum of the infinite weak chamber of some examples of N=2
supersymmetric gauge models without and with quark hypermultiplets.Comment: 17 pages, 1 figur
Quantum Theory of High Harmonic Generation via Above Threshold Ionization and Stimulated Recombination
Fully quantum treatment explicitly presents the high harmonic generation as a
three-stage process: above threshold ionization (ATI) is followed by the
continuum electron propagation in a laser field and subsequent stimulated
recombination back into the initial state. The contributions of all ATI
channels add up coherently. All three stages of the process are described by
simple, mostly analytical expressions. A very good quantitative agreement with
the previous calculations on the harmonic generation by H ion is
demonstrated, thus supplementing the conceptual significance of the theory with
its practical efficiency.Comment: Latex IOP stile, plus 1 figure in a PostScript fil
Adiabatic mechanism of the multiply charged ion production by a laser field through ATI states of an atom
ATI can be followed by an inelastic collision of the ionized electron with
the parent atomic particle resulting in an excitation of the ion. It may be a
continuum state excitation producing the doubly charged ion or a discrete state
which also enhances the doubly charged ion production. Absorption of a few
quanta above the atomic threshold is sufficient to make this mechanism work. As
a result the two-electron processes can take place even in moderate fields. The
example of two-electron excitations of He atoms in a 780 nm laser field with
intensity above W/cm is discussedComment: 12 pages, Revtex, 1 Postscript figure. Accepted for publication in
Phys.Lett.
- …