556 research outputs found
Acceleration of a polarized neutron by its weak nuclear self-interaction
It is proven that the rotation of the spin of a polarized neutron is
accompanied by a net nuclear force upon it. This force arises from the weak
nuclear self-interaction of its constituent quarks, whose chiral nature induces
the transfer of a net momentum to the fields of Z and W-bosons. This effect is
linear in Fermi's constant. As a result, it is estimated that along the
spin-flip of a polarized neutron its velocity undergoes a variation of the
order of meters per second.Comment: 4-page article + 6-page appendix + 1 figur
Topological Defects from First Order Gauge Theory Phase Transitions
We investigate the mechanism by which topological defects form in first order
phase transitions with a charged order parameter. We show how thick
superconductor vortices and heavy cosmic strings form by trapping of magnetic
flux. In an external magnetic field, intermediate objects such as strips and
membranes of magnetic flux and chains of single winding defects are produced.
At non-zero temperature, a variety of spontaneous defects of different winding
numbers arise. In cosmology, our results mean that the magnetic flux thermal
fluctuations get trapped in a primordial multi-tension string network. The
mechanism may also apply to the production of cosmic-like strings in brane
collisions. In a thin type-I superconductor film, flux strips are found to be
meta-stable while thick vortices are stable up to some critical value of the
winding number which increases with the thickness of the film. In addition, a
non-dissipative Josephson-like current is obtained across the strips of
quantized magnetic flux.Comment: Corrections made on sections 4,5. Higher quality figures in published
versio
Heavy cosmic strings
We argue that cosmic strings with high winding numbers generally form in
first-order gauge symmetry breaking phase transitions, and we demonstrate this
using computer simulations. These strings are heavier than single-winding
strings and therefore more easily observable. Their cosmological evolution may
also be very different.Comment: 4 pages, updated to match the published versio
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