150 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
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
Multi-fermion states for heavy fermions bound via Higgs exchange
A possibility to produce bound states of several heavy fermions, which are
bound together due to the Higgs exchange, is examined. It is shown that for 12
fermions, 6 fermions and 6 antifermions, occupying the lowest S_{1/2} shell
this bound state cannot exist if the fermion mass is below the critical value,
which depends on the Higgs mass and is found to be restricted to 320 < m_{cr} <
410 Gev/c^2 for the Higgs mass in the interval 100 < m_{H}< 200 Gev/c^2. This
estimate is derived in the relativistic mean field approximation. The
corrections are estimated to be not able to reduce significantly the critical
value for the fermion mass. Consequently there exist no bound state for 12 top
quarks, and the only feasible hope to observe a bag of 12 fermions
experimentally should rely on possible existence of heavy fermions of the next,
fourth generations.Comment: 4 pages, 3 figure
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