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                      Résumé  | 
                      I will first introduce the duality between the singlet sector of Matrix quantum 
mechanics (MQM) and the c=1 Liouville String Theory. Then, I will review various 
descriptions of the 2d Black Hole. Afterwards, I will analyse models of MQM in the 
double scaling limit that contain non-singlet states. The finite temperature 
partition function of such systems contains non-trivial winding modes (vortices) 
and is expressed in terms of a group theoretic sum over representations. 
Subsequently, I will focus on the model of Kazakov-Kostov-Kutasov when the first 
winding mode is dominant. In the limit of large representations (continuous Young 
diagrams), and depending on the values of the parameters of the model such as the 
compactification radius and the string coupling, the dual geometric background 
corresponds either to that of a long string (winding mode) condensate or the 2d 
(non-supersymmetric) semi-classical Black Hole competing with the thermal linear 
dilaton background. In the matrix model one is free to tune these parameters and 
explore various regimes of the phase diagram. I will show how this construction 
allows one to identify the origin of the microstates of the long string 
condensate/2d Black Hole arising from the non trivial representations. Finally, I 
will present some future directions.                  |