THEORETICAL PHYSICS DIVISION

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The research activity of the Division comprises a number of fields. The main thrust is in Particle Cosmology, Phenomenological Particle Physics, Physics of Hadrons, in Atomic, Molecular and Optical Physics, and in Space Physics.

In Particle Cosmology, which is the principal research activity of the Division, the main research topics have been the dynamics of the electroweak phase transition and the physics related to the primordial magnetic fields. A central issue has been the possible creation of baryon asymmetry of the Universe during the electroweak phase transition. The general problem of screening in a plasma has also been investigated both analytically and numerically. Results obtained have relevance not only for cosmological phenomena but also for the physics of heavy ion collisions.

Research in Particle Phenomenology has concentrated on topics beyond the Standard Model, such as extended gauge theories and supersymmetry. The effects of R-parity breaking in supersymmetric models have been investigated in both high-energy collisions and some low-energy phenomena. The possibility of using high-energy neutrinos from active galactic nuclei for testing exotic neutrino-neutrino interactions has also been studied.

In Hadron Physics the main research topics have been study of the four-quark system using lattice methods, chiral perturbation theory applied to two-pion interactions, and pion-nucleon and eta-nucleon studies in the intermediate energy range.

In Atomic, Molecular and Optical Physics the main research topics have been cold collisions between laser-cooled atoms, quantum control of molecular wave packets, and output coupling of magnetically trapped Bose-Einstein condensates.

An important developement in the activity of the Division has been due to the chair in Space Physics founded in the summer of 1997. Theoretical studies in Space Physics have included the question of how electric current that is magnetic field aligned above the ionosphere is closed in the magnetosphere and the general problem of source and loss processes of magnetospheric plasma.

The Theoretical Physics Division has a fruitful interaction with the Helsinki Institute of Physics, and close contacts are maintained with theoretical physics groups at CERN, NORDITA and several other institutions and universities in Finland and abroad.