815 research outputs found
Scaling limit for a drainage network model
We consider the two dimensional version of a drainage network model
introduced by Gangopadhyay, Roy and Sarkar, and show that the appropriately
rescaled family of its paths converges in distribution to the Brownian web. We
do so by verifying the convergence criteria proposed by Fontes, Isopi, Newman
and Ravishankar.Comment: 15 page
Lattice Gauge Theories and the Heisenberg Antiferromagnetic Chain
We study the strongly coupled 2-flavor lattice Schwinger model and the
SU(2)-color QCD_2. The strong coupling limit, even with its inherent
nonuniversality, makes accurate predictions of the spectrum of the continuum
models and provides an intuitive picture of the gauge theory vacuum. The
massive excitations of the gauge model are computable in terms of spin-spin
correlators of the quantum Heisenberg antiferromagnetic spin-1/2 chain.Comment: Proceedings LATTICE99 (spin models), 3 page
Experimental investigation of the forces and moments due to sideslip of a series of triangular vertical and horizontal tail combinations at Mach numbers
An experimental investigation was made at Mach numbers of 1.62, 1.93, and 2.41 of a series of tail combinations consisting of triangular vertical tail attached symmetrically to a triangular horizontal tail to determine the lateral force, yawing moment, and rolling moment due to sideslip. The apex angles of both the vertical- and horizontal-tail surfaces were varied systematically in order to obtain results for an appreciable range of operating conditions. The results of the investigation indicated that, for tails having subsonic leading edges and supersonic trailing edges, the lateral-force derivative and the yawing-moment derivative were predicted satisfactorily by the method presented in NACA TN 3071 except when the leading edges approach a sonic condition. The theoretical rolling-moment derivative was in fair agreement with the experimental derivative. For the limited tests in which both the leading and trailing edges were supersonic, the prediction of the lateral-force derivative and the yawing-moment derivative obtained from NACA TN 2412 was in good agreement with the experimental derivatives, whereas the prediction of the rolling-moment derivative was fair
Testing Closed String Field Theory with Marginal Fields
We study the feasibility of level expansion and test the quartic vertex of
closed string field theory by checking the flatness of the potential in
marginal directions. The tests, which work out correctly, require the
cancellation of two contributions: one from an infinite-level computation with
the cubic vertex and the other from a finite-level computation with the quartic
vertex. The numerical results suggest that the quartic vertex contributions are
comparable or smaller than those of level four fields.Comment: 14 pages, LaTeX. v2: New references to work of Beccaria and Rampino,
and Taylor. Improved numerical analysis at the end of section
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