Nuclear Physics Seminar

"Gauge Invariance and Energy-Momentum Operators -- Conflict or Opportunity?"

Presented by Terry Goldman, LANL

Tuesday, February 21, 2012, 11:00 am — Small Seminar Room, Bldg. 510

Early on in any interacting field theory course, it will be pointed out that the effectofvirtual exchanges makes it impossible in principle to separate the energy and momentum contributions of the individual fields to a total system. Yet we do this all the time: The energy of an electron bound in an atom, the angular momentum of the pions "in" a rho meson, ... and in gauge field theories, even QED, the problem seems even worse: the canonical and mechanical momenta are gauge invariant or satisfy the required commutation relations, but neither does both.
Based on an old concern regarding derivation of the Pauli Hamiltonian from the Dirac Hamiltonian,the Nanjing group has proposed a novel solution that seems to provide for exactly the desired separation -- but only in gauge theories!

Hosted by: Les Bland

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