SUGRA?

SUGRA is the acronym for supergravity grand unified models.

SUGRA models contain the standard model and gravity within their framework and thus provide an ideal springboard for the next step, i.e., to search for the fully unified model of particle physics and gravity. Such a model is expected to emerge from string theory and thus one of the main aims of the SUGRA20 conference is to discuss models based on strings and branes and explore possible links between such models and SUGRA.

SUGRA models, the earliest of which were formulated in 1982, provide the first example of phenomenologically viable models where supersymmetry is broken spontaneously via a super Higgs mechanism in a hidden sector. This breaking is communicated to the physical sector to generate soft breaking terms. The concept of the hidden sector first surfaced in this context.

SUGRA models possess the remarkable feature that the soft parameters are free of high scales, e.g., of the grand unification scale, and thus can be as low as the electroweak scale. Further, the models possess another remarkable feature, i.e., that the renormalization group evolution of the soft parameters from the grand unification scale down to the electroweak scale can trigger spontaneous breaking of the electroweak symmetry and generate a mass for the W and Z bosons. The simplest version of SUGRA, called mSUGRA, is based on the assumption of a flat Kahler potential and depends on only four parameters in addition to the parameters of the standard mode, thus mSUGRA is very predictive. Currently mSUGRA is a leading benchmark model for testing physics beyond the standard model at colliders. Another remarkable feature of mSUGRA is that under the assumption of R parity conservation it can predict just the right amount of neutralino relic density consistent with the current astrophysical constraints.