7,762 research outputs found
Recursive Stochastic Effects in Valley Hybrid Inflation
Hybrid Inflation is a two-field model where inflation ends by a tachyonic
instability, the duration of which is determined by stochastic effects and has
important observational implications. Making use of the recursive approach to
the stochastic formalism presented in Ref. [1], these effects are consistently
computed. Through an analysis of back-reaction, this method is shown to
converge in the valley but points toward an (expected) instability in the
waterfall. It is further shown that quasi-stationarity of the auxiliary field
distribution breaks down in the case of a short-lived waterfall. It is found
that the typical dispersion of the waterfall field at the critical point is
then diminished, thus increasing the duration of the waterfall phase and
jeopardizing the possibility of a short transition. Finally, it is found that
stochastic effects worsen the blue tilt of the curvature perturbations by an
order one factor when compared with the usual slow-roll contribution.Comment: 26 pages, 6 figure
Young's integral inequality with upper and lower bounds
Young's integral inequality is reformulated with upper and lower bounds for
the remainder. The new inequalities improve Young's integral inequality on all
time scales, such that the case where equality holds becomes particularly
transparent in this new presentation. The corresponding results for difference
equations are given, and several examples are included. We extend these results
to piecewise-monotone functions as well.Comment: 8 page
High-voltage dc power processing thermal control and packaging techniques
The power processor operates in several modes, delivering up to 100 amperes of regulated electrical power, operating at input voltages to 375 volts with outputs controlled by an integral microprocessor. Several alternative packaging concepts are discussed and evaluated. High-voltage design applications, power stage interconnection and EMI considerations are also discussed. Preliminary thermal analyses were performed and the results presented for each conceptual approach with parametric study results given for the selected concept
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