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 O(N)O(N)-symmetric Non-linear Sigma Model

We conjecture that the $O(N)$-symmetric non-linear sigma model in the semi-infinite $(1+1)$-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 $x=0$.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 $W=-X^{-1}(Y_1Y_2)^{n-1} + {1\over n} (Y_1Y_2)^n - Y_3Y_4$. We will argue that (the infra-red limit of) this theory describes the topological degrees of freedom of the $c=1$ string compactified at $n$ 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

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

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