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Full-Text Articles in Physics

Transition Temperature For Weakly Interacting Homogeneous Bose Gases, Frederico F. De Souza Cruz, Marcus B. Pinto, Rudnei O. Ramos Jun 2001

Transition Temperature For Weakly Interacting Homogeneous Bose Gases, Frederico F. De Souza Cruz, Marcus B. Pinto, Rudnei O. Ramos

Dartmouth Scholarship

We apply the nonperturbative optimized linear δ expansion method to the O(N) scalar field model in three dimensions to determine the transition temperature of a dilute homogeneous Bose gas. Our results show that the shift of the transition temperature ΔTc/Tc of the interacting model, compared with the ideal-gas transition temperature, really behaves as γan1/3 where a is the s-wave scattering length and n is the number density. For N=2 our calculations yield the value γ=3.059.


Velocity Field Distributions Due To Ideal Line Vortices, Thomas D. Levi, David C. Montgomery Apr 2001

Velocity Field Distributions Due To Ideal Line Vortices, Thomas D. Levi, David C. Montgomery

Dartmouth Scholarship

We evaluate numerically the velocity field distributions produced by a bounded, two-dimensional fluid model consisting of a collection of parallel ideal line vortices. We sample at many spatial points inside a rigid circular boundary. We focus on “nearest-neighbor” contributions that result from vortices that fall (randomly) very close to the spatial points where the velocity is being sampled. We confirm that these events lead to a non-Gaussian high-velocity “tail” on an otherwise Gaussian distribution function for the Eulerian velocity field. We also investigate the behavior of distributions that do not have equilibrium mean-field probability distributions that are uniform inside the …


Affinity For Scalar Fields To Dissipate, Arjun Berera, Rudnei O. Ramos Apr 2001

Affinity For Scalar Fields To Dissipate, Arjun Berera, Rudnei O. Ramos

Dartmouth Scholarship

The zero-temperature effective equation of motion is derived for a scalar field interacting with other fields. For a broad range of cases, involving interaction with as few as one or two fields, dissipative regimes are found for the scalar field system. The zero-temperature limit constitutes a baseline effect that will be prevalent in any general statistical state. Thus, the results found here provide strong evidence that dissipation is the norm not the exception for an interacting scalar field system. For application to inflationary cosmology, this provides convincing evidence that warm inflation could be a natural dynamics once proper treatment of …