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A. P. Martin

Publications and source records attributed to A. P. Martin.

5 recordsLinked to original sources
arXiv1995

The Stability of Primordial Magnetic Fields Produced by Phase Transitions

Primordial magnetic fields seem to be a generic relic of phase transitions in the early universe. We consider a primordial electromagnetic field formed as a result of a second-order phase transition, and show that it is stable to thermal fluctuations in the period immediately following. We also show how such a field arises in first order phase transitions. In both cases there is a transitive electric field produced during the transition.

astro-ph↗
arXiv1994

Evolution of Fields in a Second Order Phase Transition

We analyse the evolution of scalar and gauge fields during a second order phase transition using a Langevin equation approach. We show that topological defects formed during the phase transition are stable to thermal fluctuations. Our method allows the field evolution to be followed throughout the phase transition, for both expanding and non-expanding Universes. The results verify the Kibble mechanism for defect formation during phase transitions.

hep-ph↗
arXiv1994

Charged Particle Scattering from Electroweak and Semi-Local Strings

The scattering of a charged fermion from an electroweak or semi-local string is investigated and a full solution obtained for both massive and massless cases. For the former, with fractional string flux, there is a helicity conserving and helicity-flip cross-section, of equal magnitude and of a modified Aharonov-Bohm form: for integer flux the strong interaction cross-section is suppressed by a logarithmic term. The results also apply for GUT cosmic strings and chiral fermions.

hep-ph↗
arXiv1994

Global Strings and the Aharonov-Bohm Effect

When a fermion interacts with a global vortex or cosmic string a solenoidal "gauge" field is induced. This results in a non-trivial scattering cross-section. For scalars and non-relativistic fermions the cross-section is similar to that of Aharonov and Bohm, but with corrections. A cosmological example is compared to one in liquid He$^{3}$-A and important differences are discovered.

hep-ph↗