New facility for particle physics with polarized cold neutrons

Abstract

Over the half century since the first observation that the free neutron is an unstable particle, the neutron decay process has always posed questions at the forefront of particle physics. Nowadays the neutron attracts great attention as a tool for investigating subtle effects in the interaction between quarks and leptons [l]. This concerns hadronic corrections to the dominating “vector—axial vector” (V–A) component, as well as searches for the other weak interaction terms, “vector + axial vector,” scalar, tensor and pseudoscalar (V+A, S, T and P), which conform to relativistic quantum field theory. The main questions considered at present are: why does nature not make use of all interaction terms which are allowed by the Lorentz invariance? what is the role of parity and time reversal symmetries and/or their violation? and what are the characteristics (masses and coupling constants) of the subnuclear or subquarkllepton virtual particles responsible for a hypothetical, very weak and short range new interaction?