Seminar by Dr. Hirohiko SHIMADA "Renormalization-group landscape and the multicritical point in the disordred O(n) loop model"

Dear all,

Mathematical and Theoretical Physics Unit(Hikami Unit) would like to invite you to a seminar by Dr. Hirohiko SHIMADA.

Speaker: Dr. Hirohiko SHIMADA (LPTENS, France)

Title: Renormalization-group landscape and the multicritical point in the disordred O(n) loop model

Abstract: Conformal field theory (CFT)  had provided us with a catalogue of exact universality classes for pure models in two dimension (2D). For the models with impurity (quenched disorder), however, corresponding CFTs are largely unknown even in 2D. In some interesting case, such as the disordered O(n) loop model, we have a line (one-parameter family) of non-trivial universality classes [1]. Quite recently,  the renormalization-group flow for this model is extracted from the landscape of the effective central charge [2] obtained by the transfer-matrix method based on the Zamolodchikov's C-theorem [3]. We confirm the central charges and critical exponents along the line of the random fixed points predicted by the replica method and 1-n expansion [1]. Furthermore, at strong-coupling, we found a line of multicritical points, which could be related to a certain supersymmetry.  If time allows, I will also discuss a new classification of 2+1D quantum critical points and recent conjectures on 3D CFT.

References: 

[1] H.S., "Disordered O(n) Loop Model and Coupled Conformal Field Theories", Nucl.Phys. B820, 707 (2009).

[2] H.S., J.L. Jacobsen, and Y.Kamiya, "Phase diagram and the strong-coupling fixed point in the disordered O(n) loop model", http://arxiv.org/abs/1308.4333

[3] A.B. Zamolodchikov, JETP Lett. 43, 730 (1986).

Host: 

Shinobu Hikami, Mathematical and Theoretical Physics Unit