[工程科技]Variational principle and energy-momentum tensor for relativistic Electrodynamics of point.pdfVIP

Preprint DFPD 06/TH/02 February 2006 Variational principle and energy–momentum tensor 6 for relativistic Electrodynamics of point charges 0 0 2 r p K. Lechner1 and P.A. Marchetti2 A 3 1 2 v 4 Dipartimento di Fisica, Universit`a degli Studi di Padova, 2 and 2 2 Istituto Nazionale di Fisica Nucleare, Sezione di Padova, 0 Via F. Marzolo, 8, 35131 Padova, Italia 6 0 / h t - p e h : v Abstract i X We give a new representation as tempered distribution for the energy–momentum r tensor of a system of charged point–particles, which is free from divergent self– a interactions, manifestly Lorentz–invariant and symmetric, and conserved. We present a covariant action for this system, that gives rise to the known Lorentz–Dirac equa- tions for the particles and entails, via Noether theorem, this energy–momentum tensor. Our action is obtained from the standard action for classical Electrody- namics, by means of a new Lorentz–invariant regularization procedure, followed by a renormalization. The method introduced here extends naturally to charged p–branes and arbitrary dimensions. Keywords: Lorentz–Dirac equation, energy–momentum tensor, Poincar`e invariance, ac- tion principle. PACS: 03.50.De, 45.20.Jj, 11.30.Cp. 1kurt.lechner@pd.infn.it 2pieralberto.marchetti@pd.infn.it 1 Introduction and Summary The dynamic