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R. J. Rivers

Publications and source records attributed to R. J. Rivers.

49 records · Page 3Linked to original sources
arXiv1998

A reexamination of quenches in Helium 4 and Helium 3

In the light of recent difficulties in observing vortices in quenches of liquid helium 4 to its superfluid state we re-examine the Zurek scenario for their production. We argue that experiments in helium 4 are unlikely to produce true vortices in the numbers originally anticipated, if at all, because of the wide Ginzberg regime and the slowness of the mechanical quenches. On the other hand, the observed production of unambiguous vortices in neutron-bombarded helium 3, with its narrow Ginzberg regime, and fast quenches, is to be expected.

cond-mat↗
arXiv1998

A Re-examination of Quenches in $^{4}$He

In the light of recent difficulties in observing vortices in quenches of liquid $^{4}$He to its superfluid state we re-examine the Zurek scenario for their production. We find that the standard prediction is suspect because of a confusion over correlation lengths.

hep-ph↗
arXiv1995

Vortex Densities and Correlations at Phase Transitions

We present a model for the formation of relativistic vortices (strings) at a quench, and calculate their density and correlations. The significance of these to early universe and condensed-matter physics is discussed.

hep-ph↗
arXiv1995

Vortex Production at Phase Transitions in Nonrelativistic and Relativistic Media

We examine string (vortex) formation at a quench for a weakly-coupled global U(1) theory when the excitation spectrum is non-relativistic. It is so similar to vortex production in the corresponding relativistic plasma as to reinforce arguments for the similarity of vorheptex production in the early universe and in low-temperature many-body physics.

hep-ph↗
arXiv1995

Vortex Production in Non-Relativistic and Relativistic Media

We examine string (vortex) formation at a quench for a weakly-coupled global U(1) theory when the excitation spectrum is non-relativistic. It is so similar to vortex production in the corresponding relativistic plasma as to reinforce arguments for the similarity of vortex production in the early universe and in low-temperature many-body physics.

hep-ph↗
arXiv1995

Winding Number Correlation Functions and Cosmic String Formation

We develop winding number correlation functions that allow us to assess the role of field fluctuations on vortex formation in an Abelian gauge theory. We compute the behavior of these correlation functions in simple circumstances and show how fluctuations are important in the vicinity of the phase transition. We further show that, in our approximation, the emerging population of long/infinite string is produced by the classical dynamics of the fields alone, being essentially unaffected by field fluctuations.

hep-ph↗
arXiv1994

The Production of Strings and Monopoles at Phase Transitions

We shall show that the density of defects produced at a second-order phase transition is determined by the correlation length of the fields. This is true both for defects appearing in the Ginzburg regime and for defects produced at a quench, when the Ginzburg regime is irrelevant. (Invited lectures given by R.J.R. to the Nato Advanced Study Institute and Euroconference on Formation and Interaction of Topological Defects, Isaac Newton Institute, Cambridge (UK), September, 1994.)

astro-ph↗
arXiv1994

The Dynamics Of Vortex And Monopole Production By Quench Induced Phase Separation

Our understanding of the mechanism by which topological defects are formed in symmetry breaking phase transitions has recently changed. We examine the non-equilibrium dynamics of defect formation for weakly-coupled global O(N) theories possessing vortices (strings) and monopoles. It is seen that, as domains form and grow, defects are swept along on their boundaries at a density of about one defect per coherence area (strings) or per coherence volume (monopoles).

hep-th↗
arXiv1994

Fluctuations at Phase Transitions

We use the closed time-path formalism to calculate fluctuations at phase transitions, both in and out of equilibrium. Specifically, we consider the creation of vortices by fluctuations, of relevance to the early universe and to $^{4}He$ superfluidity. (Invited talk to Nato Advanced Research Workshop on Electroweak Physics and the Early Universe, Sintra (Portugal), March 1994)

hep-ph↗
arXiv1994

Interactions between $U(1)$ Cosmic Strings: An Analytical Study

We derive analytic expressions for the interaction energy between two general $U(1)$ cosmic strings as the function of their relative orientation and the ratio of the coupling constants in the model. The results are relevant to the statistic description of strings away from critical coupling and shed some light on the mechanisms involved in string formation and the evolution of string networks.

hep-ph↗