Meetings take theorists beyond the Standard Model

23 September 1998

To strengthen research links between theorists working on physics beyond the Standard Model, high-energy theory groups at Bonn (H P Nilles), Oxford (G Ross), Padua (F Zwirner), Pisa (R Barbieri), Warsaw (S Pokorski), Ecole Polytechnique in Palaiseau (I Antoniadis), CERN (J Ellis), and ICTP (G Senjanovic) and SISSA (A Masiero) in Trieste initiated a new series of annual meetings “From Planck Scale to Electroweak Scale”, emphasizing the span of the underlying fundamental processes.

The first meeting was organized in Kazimierz, Poland, an old grain-shipping town on the Vistula, this spring. Its topicality was underlined by the Superkamiokande results for neutrino oscillations and new limits on the proton decay life time.

A major focus of the meeting was the status of the search for the Higgs boson. The Higgs boson is not only the missing link of the Standard Model, but its discovery would also be a bridge to new physics. The new lower limit on the Higgs boson mass from CERN’s LEP2 (above 90 GeV) pushes it for the first time into the region most expected from fits to electroweak precision data and central for the predictions of the Minimal Supersymmetric Standard Model.

With the discovery potential in the last phase of LEP2 extending to the Higgs masses up to almost 110 GeV,
the long-awaited particle could make a dramatic appearance. As confirmed by recent theoretical calculations, this region covers most of the range for the Higgs mass predicted by supersymmetry.

The second major theme of the meeting was what is generally now considered as the most plausible framework for the Theory of Everything, what was formerly known as string theory. This approach is now formulated in a non-perturbative manner, termed M-theory.

The focus was on phenomenological aspects of M-theory, to find low energy, observable and testable predictions of various theoretical frameworks for this large-scale physics.

M-theory unifies in a phenomenologically successful way all known forces of Nature, including gravity. Thus the longstanding problem of string theory, the mismatch between the gauge coupling and gravity unification scales, is solved. The basic ingredient of this solution is the presence of an extra, fifth, dimension at the energy scale well below the gauge coupling unification scale.

Recent investigations, reported at the meeting, explore other phenomenological consequences of such a five dimensional world, which opens up at the energy scale 1015 GeV (or, as some speculate, even much below). For instance the fifth dimension could be seen via the pattern of soft supersymmetry breaking or in proton decay.

The next meeting in the series will be organized by Bonn and held 19­24 April 1999 in Bad Honnef (Germany). The plans for the year 2000 are to have a meeting in Gran Sasso, organized by the Italian groups.

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