Particle theory

Abstract:

We consider the hypothesis that the recently reported anomaly in the time structure of signals in the KARMEN experiment is due to the production of a light photino (or Zino) which decays radiatively due to violation of R-parity. Such a particle is shown to be consistent with all experimental data and with cosmological nucleosynthesis. There are difficulties with constraints from SN 1987A but these may be evaded if squarks are non-degenerate in mass.

Abstract:

We study the Abelian projection of SU(2) instantons in the maximally Abelian gauge. We find that in this gauge an isolated instanton produces a closed monopole loop within its core and the size of this loop increases with the core size. We show that this result is robust against the introduction of small quantum fluctuations. We investigate the effects of neighbouring (anti-) instantons upon each other and show how overlapping (anti-) instantons can generate larger monopole loops. We find, however, that in fields that are typical of the fully quantised vacuum only some of the large monopole loops that are important for confinement have a topological origin. We comment on what this may imply for the rôle of instantons in confinement and chiral symmetry breaking.