Nima Arkani-Hamed
Department of Physics
Harvard University
University of California, Berkeley
Deconstructing Dimensions: Adventures in Theory Space
The world around us appears to be four-dimensional, but it is
an old idea that extra dimensions may be revealed as we probe shorter
distances. In an inversion of this picture, it has recently been realized
that in some cases extra dimensions can be generated dynamically, emerging
as the long-distance description of a class of fundamentally
four-dimensional models. The particles and interactions of these
four-dimensional theories are conveniently described by a diagram or
``theory space". In some phases, the theory space is transmuted into extra
dimensions, while in different phases other surprising phenomena are
uncovered. These ideas have opened up a new realm of possibilities for
physics beyond the standard model, with novel predictions for upcoming
accelerator experiments. Among other things, the breaking of electroweak
symmetry can be naturally triggered by extended objects in theory space,
and the unification of forces can be accelerated to occur at energies far
lower than the conventional grand unification scale.