The interaction of an electron with a polar molecule is shown to be the simplest realization of a quantum anomaly in a physical system. The existence of a critical dipole moment for electron capture and formation of anions, which has been confirmed experimentally and numerically, is derived. This phenomenon is a manifestation of the anomaly associated with quantum symmetry breaking of the class...

1. Introduction Since the first measurements of the velocity distribution of atoms evaporating from the surface of bulk liquid helium by Johnston and King, several theories have been advanced to explain the helium evaporation process. In these theories, the excita-tions in liquid He II, phonons and rotons, play an important role in the evaporation mechanism. In this report, we discuss an experi...

Molecular motors convert chemical energy into mechanical force and movement. Operating at energies just above those of the thermal bath, these motors experience large fluctuations, and their physical description must be necessarily stochastic. Here, motor operation is described as a biased diffusion on a potential energy surface defined by the interactions of the motor with its track and its fu...