Table Of ContentActa Physica Austriaca
Supplementum XIV
Proceedings of the
XIV. Internationale Universitatswochen fUr Kernphysik 1975
der Karl-Franzens-Universitat Graz
at Schladming (Steiermark, Austria)
24th February-7th March 1975
Sponsored by
Bundesministerium fur Wissenschaft und Forschung
Steiermarkische Landesregierung
Sektion Industrie der Kammer der
gewerblichen Wirtschaft fur Steiermark
International Centre for Theoretical Physics, Triest
1975
Springer-Verlag
Wien New York
Electromagnetic Interactions
and Field Theory
Edited by Paul Urban, Graz
With 107 Figures
1975
Springer-Verlag
Wien New York
Organizing Committee
Chairman
Prof. Dr. Paul Urban
Vorstand des Institutes fUr Theoretische Physik
der Universitiit Graz
Committee Members
Doz. Dr. H. Latal
Doz. Dr. N. Pucker
Dr. A. Mas-Parareda
Dr. W. Plessas
Dr. L. Pittner
Secretary
M. Krautilik
. This work is subject to oopyright.
All rights are reserved, whether the whole or part of the material is concerned,
specifically those of translation, reprinting, re-use of illustrations, broadcasting,
reproduction by photocopying machine or similar means, and storage in data banks.
© 1975 by Springer-Verlag / Wien
Softcover reprint of the hardcover 1st edition 1975
Library of Congress Cataloging in Publication Data
Internationale Universit~tswochen fUr Kernphysik
der Karl-Franzens-Universit~t Graz, 14th,
Schladming, Austria, 1975.
Electromagnetic interactions and field theory.
(Acta physica Austriaca. Sup~lementum; 14)
1. Electromagnetic interactions--Congresses.
2. Quantum field theory--Congresses. 1. Urban,
Paul Oskar, 1905- II. Austria. Bundesminis-
terium fUr Wissenschaft und Forschung. III. Title.
IV. Series.
QC794.155 1975 530.1'4 75-19399
ISBN-13:978-3-7091-8426-4 e-ISBN-13:978-3-7091-8424-0
DOl: 10.1007/978-3-7091-8424-0
CONTENTS
URBAN, P. ,Opening Add:tess............................... 1
ROLLNIK, H., Photon hadron interaction in the reson-
ance reg ion. • . . . . . . . . . . . • • . . • . . . . . • . . . . . . . . . . . . 5
BARTL, A., Two-body and quasi-tow-body electro- and
photoproduction at high energies............... 89
ELLIS, J., e+e- annihilation, the new particles, and
charm. • . . • . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . 1 4 3
SCHOPPER, H., Physics with e+e--storage rings........... 233
GOURDIN, M., Phenomenology of weak currents............. 307
MITTER, H., Quantum electrodynamics in laser fields..... 397
CIULLI,S.,POMPONIU,C.and STEFANESCU,I.S., Analytic
extrapolation techniques and stability pro-
plems in dispersion relation theory.............. 469
SCHWINGER, J., Source theory viewpoints in deep in-
elastic scattering............................. 471
DITTRICH, W., Vacuum polarization, source- and other-
wise........................................... 489
ROMER, H., Spontaneous mass generation, renormalizat-
ion group and solvable U(N)-symmetric models... 521
BIRITZ, H., A second look at relativistic wave equat-
ions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
HAAG, R., Structural questions in quantum field theory.. 567
KLAUDER, J.R., Stochastic processes and quantum theory.. 581
THIRRING, W., Convexity properties of Coulomb systems... 631
RUHL, W., Finite conformal transformations in local
quan t um fie ld the ory . . . . . . . . . . . . . • . • • . . . . . . . . . . 643
PIETSCHMANN, H., Summary................................ 667
Acta Physica Austriaca, Suppl. XIV, 1 - 3 (1975)
© by Springer-Verlag 1975
OPENING ADDRESS
by
P. URBAN
Institut fUr Theoretische Physik
Universitat Graz
It is a great pleasure for me to welcome you most
cordially at our fourteenth International Winter School
in Schladming. About onehundred and sixty scientists from
seventeen countries participate this year, which number
gives us confidence that our efforts to provide an inter
esting program of lectures were successful.
In summer last year when we finalized the program
of this year's meeting we couldn't anticipate that in
November the surprising discovery of new long-lived par
ticles would stir up the physicists and would even pro
duce headlines in the newspapers. Since the original re-
,
ports about the new particles a wealth of scientific pa
pers to their interpretation has appeared and further
experimental data are continuously being published. We
are now in the fortunate position that among our lectu
rers we invited some experts especially to this topic of
utmost actuality which will present us with the newest
results and attempts at interpretations both from the
experimental and theoretical viewpoint.
Acta Physic. Austri.ca, Suppl. XIV
2
As is well known these particles have been disco
vered as narrow resonances in the electron-positron
channel by which fact the already highly interesting phy
sics of storage rings gained further impetus. Theoreti
cians, who comprise the main part of our participants,
will get the opportunity to obtain some insight into the
experimental problems of this area, but of course also
lectures on the current theoretical ideas about the inter
pretation of the experimental data are scheduled.
Another area of electromagnetic interactions com
prises electro- and photoproduction; i.e. the production
of a number of particles through inelastic scattering by
electrons or photons. There two regions are to be distin
guished where different theoretical methods are employed:
on the one hand production at high energies where asympto
tic approximations can be made, and on the other hand at
lower energies where resonances dominate. We will hear
lectures also about other aspects of inelastic lepton
scattering, especially in connection with new concepts
of gauge theories, as the appearance of neutral currents.
It is a great honor for us that one of the founders
of quantum electrodynamics, Prof. Schwinger, has accepted
our invitation and will talk extensively here in Schladming
about his formulations of quantum field theory and recent
results in the description of deep inelastic processes.
Also purely quantum electrodynamical question will have
their say: here an interesting area of research is the
interaction with intense electromagnetic fields as they
could be achieved e.g. by means of lasers.
The second topic of this year's meeting is concerned
with somewhat more abstract problems: both structural
questions in quantum field theory and stochastic processes
3
will be treated. In addition some aspects of mathemati
cal physics will be discussed.
As always some seminars will supplement the main
lectures and thus complete the scientific program. I
hope that also this year we will be successful in pro
viding new insights, this time mainly into the problems
of electromagnetic interactions and field theory and
wish to all of you a successful and pleasant stay here
in Schladming.
Acta Physica Austriaca. Suppl. XIV. 5 -87 (1975)
© by Springer-Verlag 1975
PHOTON HADRON INTERACTION IN THE RESONANCE
REGION+
by
H. ROLLNIK
Physikalisches Institut der
Universit&t Bonn
I. INTRODUCTION
In these lectures I shall describe the progress of
our understanding of the photon hadron interaction in the
resonance region. I will address myself to the fundamen
tal properties of the electromagnetic hadron current and
its behaviour under symmetries as well as to a detailed
description of photon couplings of hadronic states. The
progress to date is based on an impressive accumulation
of experimental information about photon hadron processes
and its phenomenological interpretation and has led to a
remarkable improvement of our insight in the electromag
netic structures of hadrons.
Most of the new results have been obtained for
+
Lecture given at XIV. Internationale Universit&tswochen fUr
Kernphysik,Schladming,Austria,February 24 - March 7, 1975.
6
baryon states and real photons. Therefore I shall con
centrate mainly on processes where real photons interact
with nucleons and shall deal with other topics, especially
with virtual photons, only if it helps to clarify the ge
neral picture. However, the next section II is devoted to
a rather general kinematical discussion of the photon
transition operator by which we hope to give a sound basis
for the application of light cone algebra ideas. Then we
turn to concrete questions starting with a short descript
ion of the present evidence for time reversal invariance
and the absence of exotic pieces in the hadronic current.
This information comes mainly from the ~(1232)-energy re
gion. What we can learn on the yN~-coupling and how accur
ate our knowledge is will be described in section IV. The
much more complicated situation for the higher isobars will
be dealt with in the following section where I shall try to
explain the basic ingredients of the so called "multipole
analyses", their results and shortcomings, without burdening
the reader with too many technical details. ,There is only
one physical scheme by which the many photon-baryon coup
lings thus obtained have been interpreted with increasing
success: the quark model and related symmetry approaches.
The last part of the lectures are devoted to a detailed
exposition of their consequences for photon hadron physics.
II. THE LIGHT-LIKE ELECTRIC DIPOLE OPERATOR
Let us start with a general, mainly kinematical dis
cussion of the transition amplitude for the photonic ex
citation
y + A + B
