Momentum creation by vortices in 3 He experiments as a model of primordial

Momentum creation by vortices in 3 He experiments as a model of primordial baryogenesis. An important problem in cosmology is why the universe contains so much more matter than antimatter. Such an imbalance can result from processes in which baryon number is not conserved. These may have occured during the electroweak phase transition in the early universe when elementary particles first acquired mass [1–3]. The standard model of particle physics has been thoroughly tested in terrestrial accelerator experiments where relatively low energies are involved and perturbation theory can be used to make predictions. But these experiments and calculations are unable to probe the processes expected to occur during the electroweak phase transition, which involve large departures from the vacuum state. It is worthwhile therefore to investigate systems where similar processes can be studied experimentally. Superfluid 3 He has many similarities to the standard electroweak model [4]. The analogue of cosmic string production has already been demonstrated in condensed matter [5–9]. Here we explain how recent 3 He experiments at Manchester demonstrate the creation of excitation momentum (momentogenesis) by quantized vortices, 1 a process analogous to baryogenesis within cosmic strings.