High Energy Theory Seminar

In the algebraic approach to quantum theory the primary notion is an associative algebra with involution (algebra of  observables). If there exists a commutative algebra of symmetries considered as automorphisms of the algebra of observables  we can define a notion of particle as elementary excitation of ground state and quasiparticle as elementary excitation of  translation invariant state.  To consider scattering of particles we should impose some additional conditions (asymptotic commutativity of algebra of observables or cluster property).  I will introduce the notion of an inclusive scattering matrix closely related  to inclusive cross sections and show that it can be expressed in terms of generalized Green  functions  that appear in Keldysh formalism of non-equilibrium statistical physics. 

The conventional scattering matrix does exist if almost every state decays into particles as the time tends to infinity.  Inclusive scattering matrix exists in much more general situations.

The talk is in 469 Lauritsen.

Contact theoryinfo@caltech.edu for Zoom information.