Holger Bech NIELSEN
Niels Bohr Institute, Copenhagen, DENMARK
E-mail: hbech@nbi.dk

Possible manifestations of the Multiple Point Principle in nature

Abstract:
The Multiple Point Principle (MPP) states that fundamental physical parameters assume values that correspond to having a maximal number of different coexisting ''phases'' for the physically realized vacuum. There is phenomenological evidence suggesting that some or all of the about 20 parameters in the Standard Model (SM) that are not predicted within the framework of the SM correspond to the MPP values of these parameters. We originally formulated the MPP in conjunction with a model for the origin of the Standard Model Group (SMG) in which the SMG emerges as the Planck scale breakdown of our AGUT gauge group (i.e., essentially the N_gen-fold replication of the of the SMG). Gauge coupling values were then predicted by implementing MPP in the context of a lattice gauge theory: the realized values of gauge couplings are those corresponding to the coexistence of the maximum number of lattice artefact phases. MPP is a mechanism for fine tuning.

At a more fundamental level, there are arguments suggesting that MPP arrises as the compromise that allows the non locality seemingly needed to solve the cosmological constant problem to be present in a phenomenologically acceptable form.

In more recent times, also others have been involved in using MPP in other ways. E.g., MPP alone has been used to predict m_Higgs and m_top where the latter was in excellent agreement with the experimental value. In recent work, what we mean by coexisting phases has been reformulated to encompass the possibility of physically realized  condensates of more or less fundamental particles. To this end we have considered the Thirring Model bosonization of the sine-Gordon Equation.