8,127 research outputs found
Bound State Boundary S-matrix of the sine-Gordon Model
We study the boundary S-matrix for the reflection of bound states of the
two-dimensional sine-Gordon integrable field theory in the presence of a
boundary.Comment: 9 pages, RU-93-5
Boundary S-matrix of the -symmetric Non-linear Sigma Model
We conjecture that the -symmetric non-linear sigma model in the
semi-infinite -dimensional space is ``integrable'' with respect to the
``free'' and the ``fixed'' boundary conditions. We then derive, for both cases,
the boundary S-matrix for the reflection of massive particles of this model off
the boundary at .Comment: 9 pages, RU-94-0
Notes on a singular Landau-Ginzburg family
We study some properties of a singular Landau-Ginzburg family characterized
by the multi-variable superpotential . We will argue that (the infra-red limit of) this theory
describes the topological degrees of freedom of the string compactified
at times the self-dual radius. We also briefly comment on the possible
realization of these line singularities as singularities of Calabi-Yau
manifolds.Comment: 16 pages in harvmac (b
Atmospheric neutrinos as a probe of eV^2-scale active-sterile oscillations
The down-going atmospheric \nu_{\mu} and {\bar{\nu_{\mu}}} fluxes can be
significantly altered due to the presence of eV^2-scale active-sterile
oscillations. We study the sensitivity of a large Liquid Argon detector and a
large magnetized iron detector (like the proposed ICAL at INO) to these
oscillations. Such oscillations are indicated by results from LSND, and more
recently, from MiniBooNE and from reanalyses of reactor experiments following
recent recalculations of reactor fluxes. There are other tentative indications
of the presence of sterile states in both the \nu and {\bar{\nu}} sectors as
well. Using the allowed sterile parameter ranges in a 3+1 mixing framework in
order to test these results, we perform a fit assuming active-sterile
oscillations in both the muon neutrino and antineutrino sectors, and compute
oscillation exclusion limits using atmospheric down-going muon neutrino and
anti-neutrino events. We find that (for both \nu_{\mu} and {\bar{\nu_{\mu}}}) a
Liquid Argon detector, an ICAL-like detector or a combined analysis of both
detectors with an exposure of 1 Mt yr provides significant sensitivity to
regions of parameter space in the range 0.1 < \Delta m^2 < 5 eV^2 for \sin^2
2\Theta_{\mu\mu}\geq 0.08. Thus atmospheric neutrino experiments can provide
complementary coverage in these regions, improving sensitivity limits in
combination with bounds from other experiments on these parameters. We also
analyse the bounds using muon antineutrino events only and compare them with
the results from MiniBooNE.Comment: 9 pages, 7 figures. Major revisions, analysis of Liquid Argon
detector added. Version to appear in Physical Review D (Brief Reports
Learning Sparse Polymatrix Games in Polynomial Time and Sample Complexity
We consider the problem of learning sparse polymatrix games from observations
of strategic interactions. We show that a polynomial time method based on
-group regularized logistic regression recovers a game, whose Nash
equilibria are the -Nash equilibria of the game from which the data
was generated (true game), in samples of
strategy profiles --- where is the maximum number of pure strategies of a
player, is the number of players, and is the maximum degree of the game
graph. Under slightly more stringent separability conditions on the payoff
matrices of the true game, we show that our method learns a game with the exact
same Nash equilibria as the true game. We also show that
samples are necessary for any method to consistently recover a game, with the
same Nash-equilibria as the true game, from observations of strategic
interactions. We verify our theoretical results through simulation experiments
Stability of the Travelling Front of a Decaying Brane
The dynamics (in light-cone time) of the tachyon on an unstable brane in the
background of a dilaton linear along a null coordinate is a non-local
reaction-diffusion type equation, which admits a travelling front solution. We
analyze the (in-)stability of this solution using linearized perturbation
theory. We find that the front solution obtained in singular perturbation
method is stable. However, these inhomogenous solutions (unlike the homogenous
solution) also have Lyapunov exponents corresponding to unstable modes around
the (meta-)stable vacuum.Comment: 1+15 pages, 4 figure
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