Speaker: Xavier Artru - Institut de Physique Nucléaire de Lyon, Univ. Lyon, UCBL, CNRS

Tuesday 18/6/2019 at 16.00

Aula B, Dipartimento di Fisica, Via A. Valerio 2, Trieste

Abstract:

Constraints on spin observables coming from discrete symmetries such as P, C,

T and identical particles may be divided in two types: 1) classical ones, which insure

the invariance of the cross sections under the symmetry operation; 2) non-classical

ones, which can only be obtained at the level of amplitudes. Similarly, positivity

constraints can be divided into classical and non-classical constraints. The former

insure the positivity of the cross section for arbitrary individual polarisations of

the external particles, the latter extend this requirement to the case of entangled

external spins. The domain of classical positivity is shown to be dual to the domain

of separability.