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## Full-Text Articles in Physics

Critical Slowing Down Of Cluster Algorithms For Ising Models Coupled To 2-D Gravity, Mark Bowick, Marco Falcioni, Geoffrey Harris, Enzo Marinari

#### Critical Slowing Down Of Cluster Algorithms For Ising Models Coupled To 2-D Gravity, Mark Bowick, Marco Falcioni, Geoffrey Harris, Enzo Marinari

*Physics*

We simulate single and multiple Ising models coupled to 2-d gravity using both the Swendsen-Wang and Wolff algorithms to update the spins. We study the integrated autocorrelation time and find that there is considerable critical slowing down, particularly in the magnetization. We argue that this is primarily due to the local nature of the dynamical triangulation algorithm and to the generation of a distribution of baby universes which inhibits cluster growth.

Radial Excited States For Heavy Quark Systems In Nrqcd, Simon Catterall, F. R. Devlin, I. T. Drummond, R. R. Hogan

#### Radial Excited States For Heavy Quark Systems In Nrqcd, Simon Catterall, F. R. Devlin, I. T. Drummond, R. R. Hogan

*Physics*

Following the Non-Relativistic QCD approach we use a gauge invariant smearing method with factorization to measure the excitation energies for a heavy Q\bar{Q} system on a 24^3\times 48 lattice at \beta=6.2. The results come from averaging over an ensemble of 60 QCD configurations. In order to enhance the signal from each configuration we use wall sources for quark propagators. The quark Hamiltonian contains only the simplest non-relativistic kinetic energy term. The results are listed for a range of bare quark masses. The mass splittings are insensitive to this variable though there are a slight ...

Resonant And Non-Resonant Pieces Of The D\Rightarrow \Bar{K}Π Semileptonic Transition Amplitude, Joseph Schechter, A. Subbaraman, S. Surya

#### Resonant And Non-Resonant Pieces Of The D\Rightarrow \Bar{K}Π Semileptonic Transition Amplitude, Joseph Schechter, A. Subbaraman, S. Surya

*Physics*

We compare the resonant and non-resonant contributions in various regions of phase space for the D\rightarrow \bar{K}\p semileptonic transition amplitude, computed in a chiral model which incorporates the heavy quark symmetry. Remarks on the significance for experiment and for chiral perturbation theory are made. hep-ph/yymmnnn

Avalanches And The Renormalization Group For Pinned Charge-Density Waves, Alan Middleton, Onuttom Narayan

#### Avalanches And The Renormalization Group For Pinned Charge-Density Waves, Alan Middleton, Onuttom Narayan

*Physics*

The critical behavior of charge-density waves (CDWs) in the pinned phase is studied for applied fields increasing toward the threshold field, using recently developed renormalization group techniques and simulations of automaton models. Despite the existence of many metastable states in the pinned state of the CDW, the renormalization group treatment can be used successfully to find the divergences in the polarization and the correlation length, and, to first order in an $\epsilon = 4-d$ expansion, the diverging time scale. The automaton models studied are a charge-density wave model and a ``sandpile'' model with periodic boundary conditions; these models are found to ...

Three-Dimensional Quantum Gravity Coupled To Gauge Fields, Simon Catterall, Ray L. Renken, John B. Kogut

#### Three-Dimensional Quantum Gravity Coupled To Gauge Fields, Simon Catterall, Ray L. Renken, John B. Kogut

*Physics*

We show how to simulate U(1) gauge fields coupled to three-dimensional quantum gravity and then examine the phase diagram of this system. Quenched mean field theory suggests that a transition separates confined and deconfined phases (for the gauge matter) in both the negative curvature phase and the positive curvature phase of the quantum gravity, but numerical simulations find no evidence for such transitions.

The Xy Model On A Dynamical Random Lattice, Simon Catterall, John B. Kogut, Ray L. Renken

#### The Xy Model On A Dynamical Random Lattice, Simon Catterall, John B. Kogut, Ray L. Renken

*Physics*

We study the XY model on a lattice with fluctuating connectivity. The expectation is that at an appropriate critical point such a system corresponds to a compactified boson coupled to 2d quantum gravity. Our simulations focus, in particular, on the important topological features of the system. The results lend strong support to the two phase structure predicted on the basis of analytical calculations. A careful finite size scaling analysis yields estimates for the critical exponents in the low temperature phase.

Heavy Quark Solitons, Joseph Schechter, Kumar S. Gupta, M. Arshad Momen, A. Subbaraman

#### Heavy Quark Solitons, Joseph Schechter, Kumar S. Gupta, M. Arshad Momen, A. Subbaraman

*Physics*

We investigate the heavy baryons which arise as solitonic excitations in a ``heavy meson" chiral Lagrangian which includes the light vector particles. It is found that the effect of the light vectors may be substantial. We also present a simple derivation which clearly shows the connection to the Callan-Klebanov approach.