Nuclear physics is presently experiencing a thrust towards fundamental phy sics questions. Low-energy experiments help in testing beyond today's stan dard models of particle physics. The search for finite neutrino masses and neutrino oscillations, for proton decay, rare and forbidden muon and pion de cays, for an electric dipole moment of the neutron denote some of the efforts to test today's theories of grand unification (GUTs, SUSYs, Superstrings, ... ) complementary to the search for new particles and symmetries in high-energy experiments. The close connections between the laws of microphysics, astrophysics and cosmology open further perspectives. This concerns, to mention some of them, properties of exotic nuclei and nuclear matter, and star evolution; the neutrino and the dark matter in the universe; relations between grand unification and evolution of the early universe. The International Symposium on Weak and Electromagnetic Interactions in Nuclei (W.E.LN. 1986)' held in Heidelberg 1-5 July 1986, in conjunction with the 600th anniversary of the University of Heidelberg, brought together experts in the fields of nuclear and particle physics, astrophysics and cosmol ogy.

This volume presents the experimental and theoretical methods of studying soft interaction physics in high energy collisions. The topics include: dynamical and Bose-Einstein correlations, multiplicity fluctuation, soft photons, disoriented chiral condensate, self-similarity and self-affine behaviors, wavelet analysis, intermittency, chaos, and phase transition.

Ch. 1. Double beta decay - historical retrospective and perspectives. 1.1. From the early days until the gauge theory era. 1.2. The nuclear physics side - nuclear matrix elements. 1.3. Double beta decay, neutrino mass models and cosmological parameters - status and prospects. 1.4. Other beyond standard model physics : from SUSY and leptoquarks to compositeness and space time structure. 1.5. The experimental race : from the late eighties to the discovery of [symbol] decay. 1.6. The future of double beta decay. 1.7. Conclusion -- ch. 2. Original articles. 2.1. From the early days until the gauge theory era. 2.2. The nuclear physics side - nuclear matrix elements. 2.3. Double beta decay, neutrino mass models and cosmological parameters - status and prospects. 2.4. Other beyond standard model physics : from SUSY and leptoquarks to compositeness and space time structure. 2.5. The experimental race : from the late eighties to the discovery of [symbol] decay. 2.6. The future of double beta decay

The purpose of the symposium is to discuss current experimental and theoretical studies of weak and electromagnetic interactions in nuclei, emphasizing fundamental problems of particle, nuclear and astrophysics. Subjects discussed included symmetries and conservation laws, neutrino physics, nuclear weak process and weak form factors, electromagnetic probes for hadrons and nuclear structures, symmetries and flavornuclei, new facilities, and others.

Nuclear double beta decay is one of the most promising tools for probing beyond-the-standard-model physics on beyond-accelerator energy scales. It is already now probing the TeV scale, on which new physics should manifest itself according to theoretical expectations. Only in the early 1980s was it known that double beta decay yields information on the Majorana mass of the exchanged neutrino. At present, the sharpest bound for the electron neutrino mass arises from this process. It is only in the last 10 years that the much more far-reaching potential of double beta decay has been discovered. Today, the potential of double beta decay includes a broad range of topics that are equally relevant to particle physics and astrophysics, such as masses of heavy neutrinos, of sneutrinos, as SUSY models, compositeness, leptoquarks, left-right symmetric models, and tests of Lorentz symmetry and equivalence principle in the neutrino sector. Double beta decay has become indispensable nowadays for solving the problem of the neutrino mass spectrum and the structure of the neutrino mass matrix — together with present and future solar and atmospheric neutrino oscillation experiments. Some future double beta experiments (like GENIUS) will be capable to be simultaneously neutrino observatories for double beta decay and low-energy solar neutrinos, and observatories for cold dark matter of ultimate sensitivity.This invaluable book outlines the development of double beta research from its beginnings until its most recent achievements, and also presents the outlook for its highly exciting future.