Integrated Calendar

It is by now well known that the AdS/CFT duality provides an interesting way of calculating anomalous dimensions at high spin, for a gauge theory at strong coupling. A high spin operator, made of adjoint fields, is represented by (or dual to) a rotating open string in anti-de Sitter space. The anomalous dimension shows up, in the string side of the correspondence, simply as the difference between string energy and spin. On the other hand it is also know that it is possible to introduce matter degrees of freedom - fields in the fundamental representation of the gauge group - in the AdS/CFT duality by introducing probe (flavour) branes. This approach leads to a nice description of meson states. So, a natural question to be asked is : can one calculate the anomalous dimension for operators in the fundamental representation, like a quark anti-quark, using AdS/CFT? This question will be the main issue of this seminar. We will see that the presence of an energy scale makes it a non trivial task the identification of a quantity representing, in the string side, the dimension of the gauge theory operator. Serching for the solution to this problem, we found a new entry in the dictionary of AdS/CFT: the anomalous dimension at high spin is proportional to the string proper length. Also, we found strong indications that, in the case of a non conformal duality, the operator properties are obtained from measurements made by a local observer (not sensible to energy scales) in the anti-de Sitter space, while the description of the states comes from a coordinate time observer. (reference: JHEP 1408, 104 (2014) at ArXiv:1405.7388)