Sphaleron

The sphaleron (from the Greek " ready to fall " ) is a hypothetical excitation of the vacuum in the standard model of particle physics, which plays a role in some theories of baryogenesis.

The sphaleron processes have been described mathematically in 1984 by Frans Klinkhamer and Nicholas Manton. You are nonperturbatively in the framework of quantum field theory of the Standard Model writable. Experimentally, they could not yet be confirmed.

The vacuum states of the electroweak theory in the standard model is not unique, and so has the potential of a periodic structure of minima. Now changes a system from a vacuum state to another, this is done by so-called Sphaleronen. These are unstable solutions of the field equations that exist between the vacua. Sphaleronen take the road over the potential barrier between the vacua ( at energies E> 100 GeV ).

It is also possible to tunnel a vacuum to the next, this process is referred to as instanton. Since tunneling effects are, however, suppressed exponentially, such processes are very unlikely.

Figuratively speaking, the Sphaleronen serve as a valve between leptons and baryons, as they can transfer the one particle to the other. On a sphaleron process take three quarks (one of each color charge ) from each of the three particle families in part, as well as one lepton from the corresponding lepton family. All must be right-handed.

Sphaleronen get the size, but violate ( B: baryon number, L: lepton number ). Thus, one can also generate a baryogenesis via leptogenesis by Sphaleronen.