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# Ofer Aharony

## Current Research Interests

- Strongly coupled field theories and confinement, Supersymmetric field theories, Large N field theories
- Non-perturbative aspects of string/M theory
- The AdS/CFT correspondence and its generalizations to other field theory/gravity dualities, and its applications for studying field theory and string/M theory

The standard model of particle physics provides an excellent description of most particle physics processes observed experimentally. Theoretically, there are two main problems with this model : the strong nuclear interactions (QCD) are strongly coupled at low energies so it is difficult to use the standard model gauge theory to obtain predictions for properties like meson and baryon masses, and the model does not contain quantum gravity.

One main research direction I am interested in is the understanding of the strong coupling behavior of field theories like QCD, in order to understand issues like confinement and chiral symmetry breaking. One method which is useful is to study supersymmetric field theories. These theories are similar in many ways to QCD, and exhibit (in some cases) the same qualitative behavior, but due to the power of supersymmetry many of their properties may be computed exactly (even at strong coupling) so one has some control over issues like confinement and chiral symmetry breaking. Another useful method is the large N expansion (pioneered by 't Hooft), where again some exact results may be obtained concerning the strong coupling behavior in the limit of a large number of colors, which perhaps could be extended to the case of the strong interactions (for which N=3).

My other main interest is in quantum gravity, which is believed to be well-described by string theory. The non-perturbative formulation of this theory is not yet completely understood, though it is understood in some gravitational backgrounds. Some particularly interesting problems in quantum gravity, which can hopefully be studied using string theory (though they cannot be studied in string perturbation theory), are the general understanding of the black hole entropy/area relation and the fate of cosmological singularities like the big-bang singularity.

Recently it has been realized that there is a direct relation between quantum field theories and quantum theories of gravity (in some backgrounds), known as the AdS/CFT correspondence (and its generalizations). In many cases this correspondence is related to 't Hooft's large N expansion, which leads one to expect that large N field theories should be related to string theories (and, thus, to theories of quantum gravity). The correspondence is a manifestation of holography, which is expected to be a general property of quantum gravity. By studying this correspondence one hopes to shed light both on properties of strongly coupled field theories (which, in some cases, are mapped to weakly coupled theories of gravity) and on properties of quantum gravity (which are mapped to properties of field theories).