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Full-Text Articles in Physics
Department Of Physics Newsletter: Spring 2002, Bob Krotkov, Gerry Peterson, Monroe Rabin
Department Of Physics Newsletter: Spring 2002, Bob Krotkov, Gerry Peterson, Monroe Rabin
Physics Newsletters
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The Two-Dimensional Bose-Einstein Condensate, Jp Fernandez, Wj Mullin
The Two-Dimensional Bose-Einstein Condensate, Jp Fernandez, Wj Mullin
Physics Department Faculty Publication Series
We study the Hartree–Fock–Bogoliubov mean-field theory as applied to a two-dimensional finite trapped Bose gas at low temperatures and find that, in the Hartree–Fock approximation, the system can be described either with or without the presence of a condensate; this is true in the thermodynamic limit as well. Of the two solutions, the one that includes a condensate has a lower free energy at all temperatures. However, the Hartree–Fock scheme neglects the presence of phonons within the system, and when we allow for the possibility of phonons we are unable to find condensed solutions; the uncondensed solutions, on the other …
Two-Dimensional Weakly Interacting Bose Gas In The Fluctuation Region, Nikolai Prokof'ev, Boris Svistunov
Two-Dimensional Weakly Interacting Bose Gas In The Fluctuation Region, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We study the crossover between the mean-field and critical behavior of the two-dimensional Bose gas throughout the fluctuation region of the Berezinskii-Kosterlitz-Thouless phase transition point. We argue that this crossover is described by universal (for all weakly interacting |ψ|4 models) relations between thermodynamic parameters of the system, including superfluid and quasicondensate densities. We establish these relations with high-precision Monte Carlo simulations of the classical |ψ|4 model on a lattice, and check their asymptotic forms against analytic expressions derived on the basis of the mean-field theory.
Self-Trapping Of Polarons In The Rashba-Pekar Model, A Mishchenko, N Nagaosa, Nikolai Prokof'ev, A Sakamoto, B Svistunov
Self-Trapping Of Polarons In The Rashba-Pekar Model, A Mishchenko, N Nagaosa, Nikolai Prokof'ev, A Sakamoto, B Svistunov
Physics Department Faculty Publication Series
We performed a quantum Monte Carlo study of the exciton-polaron model which features the self-trapping phenomenon when the coupling strength and/or particle momentum is varied. Accurate data for energy, effective mass, the structure of the polaronic cloud, dispersion law, and spectral function became available throughout the crossover region. We observed that self-trapping cannot be reduced to hybridization of two states with different lattice deformation, and that at least three states are involved in the crossover from light- to heavy-mass regimes.
Allowed Eta-Decay Modes And Chiral Symmetry, Br Holstein
Allowed Eta-Decay Modes And Chiral Symmetry, Br Holstein
Physics Department Faculty Publication Series
Recently, the development of chiral perturbation theory has allowed the generation of rigorous low-energy theorems for various hadronic processes based only on the chiral invariance of the underlying QCD Lagrangian. Such techniques are highly developed and well-tested in the domain of pionic and kaonic reactions. In this note we point out that with the addition of a few additional and reasonable assumptions similar predictive power is available for processes involving the eta meson
Ripening Of Porous Media, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey
Ripening Of Porous Media, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey
Benny Davidovitch
We address the surface tension-driven dynamics of porous media in nearly saturated pore-space solutions. We linearize this dynamics in the reaction-limited regime near its fixed points – surfaces of constant mean curvature (CMC surfaces). We prove that the only stable interface for this dynamics is the plane, and estimate the time scale for a CMC surface to become unstable. We also discuss the differences between open and closed system dynamics, pointing out the unlikelihood that CMC surfaces are ever realized in these systems on any time scale.
Invaded Cluster Simulations Of The Xy Model In Two And Three, I. Dukovski, Jonathan Machta, L. V. Chayes
Invaded Cluster Simulations Of The Xy Model In Two And Three, I. Dukovski, Jonathan Machta, L. V. Chayes
Jonathan Machta
The invaded cluster algorithm is used to study the XY model in two and three dimensions up to sizes 20002 and 1203, respectively. A soft spin O(2) model, in the same universality class as the three-dimensional XY model, is also studied. The static critical properties of the model and the dynamical properties of the algorithm are reported. The results are Kc=0.45412(2) for the three-dimensional XY model and η=0.037(2) for the three-dimensional XY universality class. For the two-dimensional XY model the results are Kc=1.120(1) and η=0.251(5). The invaded cluster algorithm does not show any critical slowing for the magnetization or critical …
Iterated Conformal Dynamics And Laplacian Growth, Felipe Barra, Benny Davidovitch, Itamar Procaccia
Iterated Conformal Dynamics And Laplacian Growth, Felipe Barra, Benny Davidovitch, Itamar Procaccia
Benny Davidovitch
The method of iterated conformal maps for the study of diffusion limited aggregates (DLA) is generalized to the study of Laplacian growth patterns and related processes. We emphasize the fundamental difference between these processes: DLA is grown serially with constant size particles, while Laplacian patterns are grown by advancing each boundary point in parallel, proportional to the gradient of the Laplacian field. We introduce a two-parameter family of growth patterns that interpolates between DLA and a discrete version of Laplacian growth. The ultraviolet putative finite-time singularities are regularized here by a minimal tip size, equivalently for all the models in …
Quantum Corrections To The Reissner–Nordström And Kerr-Newman Metrics, John Donoghue, Barry R. Holstein, Björn Garbrecht, Thomas Konstandin
Quantum Corrections To The Reissner–Nordström And Kerr-Newman Metrics, John Donoghue, Barry R. Holstein, Björn Garbrecht, Thomas Konstandin
John Donoghue
We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of non-analytic pieces , q2log(−q2), etc. in the form factors of the energy–momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner–Nordström and Kerr–Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order Gαℏ/mr3
Coiling Instabilities Of Multilamellar Tubes, Christian Santangelo, P. Pincus
Coiling Instabilities Of Multilamellar Tubes, Christian Santangelo, P. Pincus
Christian Santangelo
Myelin figures are densely packed stacks of coaxial cylindrical bilayers that are unstable to the formation of coils or double helices. These myelin figures appear to have no intrinsic chirality. We show that such cylindrical membrane stacks can develop an instability when they acquire a spontaneous curvature or when the equilibrium distance between membranes is decreased. This instability breaks the chiral symmetry of the stack and may result in coiling. A unilamellar cylindrical vesicle, on the other hand, will develop an axisymmetric instability, possibly related to the pearling instability.
Revealing The Superfluid–Mott-Insulator Transition In An Optical Lattice, V Kashurnikov, Nikolai Prokof'ev, Boris Svistunov
Revealing The Superfluid–Mott-Insulator Transition In An Optical Lattice, V Kashurnikov, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We study (by an exact numerical scheme) the single-particle density matrix of ∼103 ultracold atoms in an optical lattice with a parabolic confining potential. Our simulation is directly relevant to the interpretation and further development of the recent pioneering experiment by Greiner et al., Nature, (London) 415, 39 (2002). In particular, we show that restructuring of the spatial distribution of the superfluid component when a domain of Mott-insulator phase appears in the system, results in a fine structure of the particle momentum distribution. This feature may be used to locate the point of the superfluid–Mott-insulator transition.
Quantum Corrections To The Reissner-Nordstrom And Kerr-Newman Metrics, Jf Donoghue, Br Holstein, B Garbrecht, T Konstandin
Quantum Corrections To The Reissner-Nordstrom And Kerr-Newman Metrics, Jf Donoghue, Br Holstein, B Garbrecht, T Konstandin
Physics Department Faculty Publication Series
We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of non-analytic pieces Image , q2log(−q2), etc. in the form factors of the energy–momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner–Nordström and Kerr–Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order Gαplanck constant over two pi/mr3.