S. Karamov

Exact Lattice Supersymmetry: the Two-Dimensional N = 2 Wess-Zumino Model

We study the two-dimensional Wess-Zumino model with extended

Lattice study of the two-dimensional Wess-Zumino model

N=2

A two-dimensional lattice model with exact supersymmetry

supersymmetry on the lattice. The lattice prescription we choose has the merit of preserving exactly a single supersymmetric invariance at finite lattice spacing a. Furthermore, we construct three other transformations of the lattice fields under which the variation of the lattice action vanishes to

Testing a Fourier-accelerated hybrid Monte Carlo algorithm

{O(ga}^{2})

Observation af the Omega(0)(c) charmed baryon at CLEO

where g is a typical interaction coupling. These four transformations correspond to the two Majorana supercharges of the continuum theory. We also derive lattice Ward identities corresponding to these exact and approximate symmetries. We use dynamical fermion simulations to check the equality of the mass gaps in the boson and fermion sectors and to check the lattice Ward identities. At least for weak coupling we see no problems associated with a lack of reflection positivity in the lattice action and find good agreement with theory. At strong coupling we provide evidence that problems associated with a lack of reflection positivity are evaded for small enough lattice spacing.

Search for the Decay B(bar sign){sup 0}{yields} D{sup *0}{gamma}

We present results from a numerical simulation of the two-dimensional Euclidean Wess-Zumino model. In the continuum the theory possesses N=1 supersymmetry. The lattice model we employ was analyzed by Golterman and Petcher in \cite{susy} where a perturbative proof was given that the continuum supersymmetric Ward identities are recovered without finite tuning in the limit of vanishing lattice spacing. Our simulations demonstrate the existence of important non-perturbative effects in finite volumes which modify these conclusions. It appears that in certain regions of parameter space the vacuum state can contain solitons corresponding to field configurations which interpolate between different classical vacua. In the background of these solitons supersymmetry is partially broken and a light fermion mode is observed. At fixed coupling the critical mass separating phases of broken and unbroken supersymmetry appears to be volume dependent. We discuss the implications of our results for continuum supersymmetry breaking.

Search for the Decay B(bar sign)° D{sup *0}γ

Abstract Starting from a simple discrete model which exhibits a supersymmetric invariance we construct a local, interacting, two-dimensional Euclidean lattice theory which also admits an exact supersymmetry. This model is shown to correspond to the Wess-Zumino model with extended N = 2 supersymmetry in the continuum. We have performed dynamical fermion simulations to check the spectrum and supersymmetric Ward identities and find good agreement with theory.