The Standard Model of elementary particle physics gives a unified description of the smallest constituents of matter and the electromagnetic, weak and strong interactions among them. The Standard Model has been tested extensively in a large number of experiments and found to agree with these, with the exception of massive neutrinos. Nevertheless it suffers from a number of inconsistencies and requires extreme fine-tuning of parameters in some areas. This has led to the widespread belief that the Standard Model is the low-energy effective theory of some more fundamental theory in which all, or most, of the difficulties plaguing it are removed.
The search for this more fundamental theory is one of the main enterprises of theoretical elementary particle physics. This search has progressed with no or little guidance from experiments for decades, since no experimental result (with the exception of neutrino oscillations) has been in significant contradiction with the Standard Model. There is a general belief that this situation will change with the start of operation of the LHC accelerator at CERN. This accelerator will be the first to probe matter at an energy scale of TeV, a region where the so-far undetected Higgs boson must be produced for the internal consistency of the Standard Model. The Higgs boson is connected to the electroweak symmetry breaking.
A second problem with the Standard Model is the so-called Hierarchy Problem, the extreme fine-tuning necessary to ensure that the contributions to the physical Higgs mass from radiative corrections are small enough so that the Higgs mass stays in the region of electroweak symmetry breaking rather than being pushed up towards the Planck scale. A "natural'' solution to this problem would be that the physics of the more fundamental underlying theory becomes manifest somewhere close to the TeV scale. Among the proposed solutions one finds low energy supersymmetry, large extra dimensions and new types of gauge interactions. This argument, albeit not as solid as for the case of electroweak symmetry breaking, also indicates the possibility that new phenomena will be discovered at the LHC. The candidates for more profound models than the present Standard Model typically contain particles suitable for the so-called dark matter, measured to form a significant part of the energy content of the Universe. It is expected that with the future colliders, these elusive particles can be studied in the laboratory environment. We are therefore at the threshold of an era when the effort to find the underlying fundamental theory finally will have experimental results against which predictions can be gauged.
The program will be divided into different themes: nonminimal supersymmetry, supersymmetry without R-parity, higher-dimensional models, nonsupersymmetric models beyond the standard model, etc., with emphasis on collider studies and connection to dark matter. During a specific theme period within the program, lectures and discussion sessions on that theme are arranged.
An important input for the program would come from a
organised jointly by theorists and experimentalists.
For this workshop, Sten Hellman from the University of
Stockholm and ATLAS/CERN will act as a local organiser.
Core scientists include:
David J. Miller,
Margarida Nesbitt Rebelo,
Andrea Romanino, and