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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Geometrical Folding Transitions Of The Triangular Lattice In The Face-Centred Cubic Lattice, Mark Bowick, Oliver Golinelli, Emmanuel Guitter, S. Mori
Geometrical Folding Transitions Of The Triangular Lattice In The Face-Centred Cubic Lattice, Mark Bowick, Oliver Golinelli, Emmanuel Guitter, S. Mori
Physics - All Scholarship
We study the folding of the regular two-dimensional triangular lattice embedded in the regular three-dimensional Face-Centred Cubic lattice, a discrete model for the crumpling of membranes. Possible folds are complete planar folds, folds with the angle of a regular tetrahedron (71 degrees) or with that of a regular octahedron (109 degrees). We study this model in the presence of a negative bending rigidity K, which favours the folding process. We use both a cluster variation method (CVM) approximation and a transfer matrix approach. The system is shown to undergo two separate geometrical transitions with increasing |K|: a first discontinuous transition …
Laboratory Synthesis Of Molecular Hydrogen On Surfaces Of Astrophysical Interest, Gianfranco Vidali, V Pirronello, Chi Liu, Liyong Shen
Laboratory Synthesis Of Molecular Hydrogen On Surfaces Of Astrophysical Interest, Gianfranco Vidali, V Pirronello, Chi Liu, Liyong Shen
Physics - All Scholarship
We report on the first results of experiments to measure the recombination rate of hydrogen on surfaces of astrophysical interest. Our measurements give lower values for the recombination efficiency (sticking probability S x probability of recombination upon H-H encounter \gamma) than model-based estimates. We propose that our results can be reconciled with average estimates of the recombination rate (1/2 n(H) n(g) v(H)A S \gamma) from astronomical observations, if the actual surface of an average grain is rougher, and its area bigger, than the one considered in models.
Discrete Folding, Mark Bowick, Philippe Di Francesco, Oliver Golinelli, Emmanuel Guitter
Discrete Folding, Mark Bowick, Philippe Di Francesco, Oliver Golinelli, Emmanuel Guitter
Physics - All Scholarship
Models of folding of a triangular lattice embedded in a discrete space are studied as simple models of the crumpling transition of fixed-connectivity membranes. Both the case of planar folding and three-dimensional folding on a face-centered-cubic lattice are treated. The 3d-folding problem corresponds to a 96-vertex model and exhibits a first-order folding transition from a crumpled phase to a completely flat phase as the bending rigidity increases.
Comment On ``Confirmation Of The Sigma Meson'', Joseph Schechter, Masayasu Harada, Francesco Sannino
Comment On ``Confirmation Of The Sigma Meson'', Joseph Schechter, Masayasu Harada, Francesco Sannino
Physics - All Scholarship
We comment on the recent paper by N.A. Tornqvist and M. Roos published in Phys. Rev. Lett. 76, 1575 (1996).
Ground-State Roughness Of The Disordered Substrate And Flux Line In D=2, Alan Middleton, Chen Zeng, Y. Shapir
Ground-State Roughness Of The Disordered Substrate And Flux Line In D=2, Alan Middleton, Chen Zeng, Y. Shapir
Physics - All Scholarship
We apply optimization algorithms to the problem of finding ground states for crystalline surfaces and flux lines arrays in presence of disorder. The algorithms provide ground states in polynomial time, which provides for a more precise study of the interface widths than from Monte Carlo simulations at finite temperature. Using $d=2$ systems up to size $420^2$, with a minimum of $2 \times 10^3$ realizations at each size, we find very strong evidence for a $\ln^2(L)$ super-rough state at low temperatures.
Suppressing Curvature Fluctuations In Dynamical Triangulations, Simon Catterall, Mark Bowick, G. Thorleifssona
Suppressing Curvature Fluctuations In Dynamical Triangulations, Simon Catterall, Mark Bowick, G. Thorleifssona
Physics - All Scholarship
We study numerically the dynamical triangulation formulation of two-dimensional quantum gravity using a restricted class of triangulation, so-called minimal triangulations, in which only vertices of coordination number 5, 6, and 7 are allowed. A real-space RG analysis shows that for pure gravity (central charge c = 0) this restriction does not affect the critical behavior of the model. Furthermore, we show that the critical behavior of an Ising model coupled to minimal dynamical triangulations (c = 1/2) is still governed by the KPZ-exponents.
Blocking Of Dynamical Triangulations With Matter, Simon Catterall, E. Gregory, G. Thorleifsson
Blocking Of Dynamical Triangulations With Matter, Simon Catterall, E. Gregory, G. Thorleifsson
Physics - All Scholarship
We use the recently proposed node decimation algorithm for blocking dynamical geometries to investigate a class of models, with central charge greater than unity, coupled to 2D gravity. We demonstrate that the blocking preserves the fractal structure of the surfaces.
The Flat Phase Of Fixed-Connectivity Membranes, Simon Catterall, Mark Bowick, Marco Falcioni, G. Thorleifsson, Konstantinos N. Anagnostopoulos
The Flat Phase Of Fixed-Connectivity Membranes, Simon Catterall, Mark Bowick, Marco Falcioni, G. Thorleifsson, Konstantinos N. Anagnostopoulos
Physics - All Scholarship
The statistical mechanics of flexible two-dimensional surfaces (membranes) appears in a wide variety of physical settings. In this talk we discuss the simplest case of fixed-connectivity surfaces. We first review the current theoretical understanding of the remarkable flat phase of such membranes. We then summarize the results of a recent large scale Monte Carlo simulation of the simplest conceivable discrete realization of this system \cite{BCFTA}. We verify the existence of long-range order, determine the associated critical exponents of the flat phase and compare the results to the predictions of various theoretical models.
Simplicial Gravity In Dimension Greater Than Two, Simon Catterall, G. Thorleifsson, John B. Kogut, R. Renken
Simplicial Gravity In Dimension Greater Than Two, Simon Catterall, G. Thorleifsson, John B. Kogut, R. Renken
Physics - All Scholarship
We consider two issues in the DT model of quantum gravity. First, it is shown that the triangulation space for D>3 is dominated by triangulations containing a single singular (D-3)-simplex composed of vertices with divergent dual volumes. Second we study the ergodicity of current simulation algorithms. Results from runs conducted close to the phase transition of the four-dimensional theory are shown. We see no strong indications of ergodicity br eaking in the simulation and our data support recent claims that the transition is most probably first order. Furthermore, we show that the critical properties of the system are determined …
Comment On "Moving Glass Phase Of Driven Lattices", Leon Balents, M. Cristina Marchetti, Leo Radzihovsky
Comment On "Moving Glass Phase Of Driven Lattices", Leon Balents, M. Cristina Marchetti, Leo Radzihovsky
Physics - All Scholarship
We consider a periodic lattice rapidly driven through a quenched random potential as a model of a moving Abrikosov lattice. In addition to the transverse phonon displacements u_y, we consider the displacements u_x along the direction of motion, which were assumed to be small in earlier treatments. We show that these displacements are in fact divergent even on large length scales and therefore lead to a breakdown of the elastic model along the direction of motion. We propose that the resulting phase is a moving "smectic" with translational order that is quasi-long-range transverse and liquid-like parallel to the direction of …
Hidden Structure In A Lagrangian For Hyperfine Splitting Of The Heavy Baryons, Joseph Schechter, Masayasu Harada, Asif Qamar, Francesco Sannino, Herbert Weigel
Hidden Structure In A Lagrangian For Hyperfine Splitting Of The Heavy Baryons, Joseph Schechter, Masayasu Harada, Asif Qamar, Francesco Sannino, Herbert Weigel
Physics - All Scholarship
We investigate the hyperfine splitting of the heavy baryons in the bound-state approach. We start with an ordinary relativistic Lagrangian which has been extensively used to discuss finite mass corrections to the heavy limit predictions. It turns out that the dominant contribution arises from terms which do not manifestly break the heavy spin symmetry. The actual heavy spin violating terms are uncovered by carefully performing a 1/M expansion of this Lagrangian.
The Flat Phase Of Crystalline Membranes, Simon Catterall, Mark Bowick, Konstantinos N. Anagnostopoulos
The Flat Phase Of Crystalline Membranes, Simon Catterall, Mark Bowick, Konstantinos N. Anagnostopoulos
Physics - All Scholarship
We present the results of a high-statistics Monte Carlo simulation of a phantom crystalline (fixed-connectivity) membrane with free boundary. We verify the existence of a flat phase by examining lattices of size up to 128^2. The Hamiltonian of the model is the sum of a simple spring pair potential, with no hard-core repulsion, and bending energy. The only free parameter is the the bending rigidity \kappa. In-plane elastic constants are not explicitly introduced. We obtain the remarkable result that this simple model dynamically generates the elastic constants required to stabilise the flat phase. We present measurements of the size (Flory) …
The Flat Phase Of Crystalline Membranes, Mark Bowick, Simon Catterall, Marco Falcioni, Gudmar Thorleifsson, Konstantinos N. Anagnostopoulos
The Flat Phase Of Crystalline Membranes, Mark Bowick, Simon Catterall, Marco Falcioni, Gudmar Thorleifsson, Konstantinos N. Anagnostopoulos
Physics - All Scholarship
We present the results of a high-statistics Monte Carlo simulation of a phantom crystalline (fixed-connectivity) membrane with free boundary. We verify the existence of a flat phase by examining lattices of size up to $128^2$. The Hamiltonian of the model is the sum of a simple spring pair potential, with no hard-core repulsion, and bending energy. The only free parameter is the the bending rigidity $\kappa$. In-plane elastic constants are not explicitly introduced. We obtain the remarkable result that this simple model dynamically generates the elastic constants required to stabilise the flat phase. We present measurements of the size (Flory) …
Vortex Dynamics And Defects In Simulated Flux Flow, Alan Middleton, Michael Chance Faleski, M. C. Marchetti
Vortex Dynamics And Defects In Simulated Flux Flow, Alan Middleton, Michael Chance Faleski, M. C. Marchetti
Physics - All Scholarship
We present the results of molecular dynamic simulations of a two-dimensional vortex array driven by a uniform current through random pinning centers at zero temperature. We identify two types of flow of the driven array near the depinning threshold. For weak disorder the flux array contains few dislocation and moves via correlated displacements of patches of vortices in a {\it crinkle} motion. As the disorder strength increases, we observe a crossover to a spatially inhomogeneous regime of {\it plastic} flow, with a very defective vortex array and a channel-like structure of the flowing regions. The two regimes are characterized by …
Scaling Behavior In Soliton Models, Joseph Schechter, Masayasu Harada, F. Sannino, H. Weigel
Scaling Behavior In Soliton Models, Joseph Schechter, Masayasu Harada, F. Sannino, H. Weigel
Physics - All Scholarship
In the framework of chiral soliton models we study the behavior of static nucleon properties under rescaling of the parameters describing the effective meson theory. In particular we investigate the question of whether the Brown--Rho scaling laws are general features of such models. When going beyond the simple Skyrme model we find that restrictive constraints need to be imposed on the mesonic parameters in order to maintain these scaling laws. Furthermore, in the case when vector mesons are included in the model it turns out that the isoscalar form factor no longer scales according to these laws. Finally we note …