5,894 research outputs found
Julian Schwinger: Source Theory and the UCLA Years--- From Magnetic Charge to the Casimir Effect
Julian Schwinger began the construction of Source Theory in 1966 in response
to the then apparent failure of quantum field theory to describe strong
interactions, the physical remoteness of renormalization, and the utility of
effective actions in describing chiral dynamics. I will argue that the source
theory development was not really so abrupt a break with the past as Julian may
have implied, for the ideas and techniques in large measure were present in his
work at least as early as 1951. Those techniques and ideas are still of
fundamental importance to theoretical physics, so much so that the designation
``source theory'' has become superfluous. Julian did a great deal of innovative
physics during the last 30 years of his life, and I will touch on some of the
major themes. The impact of much of this work is not yet apparent. (Invited
talk at Washington APS/AAPT meeting)Comment: 15 pages, plain TeX, no figures, available through anonymous ftp from
ftp://euclid.tp.ph.ic.ac.uk/papers/ or on WWW at
http://euclid.tp.ph.ic.ac.uk/Papers
Anomalies in PT-Symmetric Quantum Field Theory
It is shown that a version of PT-symmetric electrodynamics based on an
axial-vector current coupling massless fermions to the photon possesses
anomalies and so is rendered nonrenormalizable. An alternative theory is
proposed based on the conventional vector current constructed from massive
Dirac fields, but in which the PT transformation properties of electromagnetic
fields are reversed. Such a theory seems to possess many attractive features.Comment: 7 pages, uses czjphys.cls, to appear in proceedings of Workshop on
Pseudo-Hermitian Hamiltonians in Quantum Physic
PT-Symmetric Quantum Field Theory
In the context of the PT-symmetric version of quantum electrodynamics, it is
argued that the C operator introduced in order to define a unitary inner
product has nothing to do with charge conjugation.Comment: 4 pages, uses czjphys.cls, to appear in the Proceedings of the 12th
International Colloquium on Quantum Groups and Integrable System
Finite-Element Time Evolution Operator for the Anharmonic Oscillator
The finite-element approach to lattice field theory is both highly accurate
(relative errors , where is the number of lattice points) and
exactly unitary (in the sense that canonical commutation relations are exactly
preserved at the lattice sites). In this talk I construct matrix elements for
dynamical variables and for the time evolution operator for the anharmonic
oscillator, for which the continuum Hamiltonian is
Construction of such matrix elements does not require solving the implicit
equations of motion. Low order approximations turn out to be extremely
accurate. For example, the matrix element of the time evolution operator in the
harmonic oscillator ground state gives a result for the anharmonic oscillator
ground state energy accurate to better than 1\%, while a two-state
approximation reduces the error to less than 0.1\%.Comment: Contribution to Harmonic Oscillators II, Cocoyoc, Mexico, March
23-25, 1994, 8 pages, OKHEP-94-01, LaTeX, one uuencoded figur
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