ELFT HÍRADÓ

[Sandor Katz <katz AT bodri.elte.hu>]

Kedves érdeklődők!

E héten a szokásostól eltérő helyen és időben lesz az elméleti fizika 
szeminárium.

Üdvözlettel,
Katz Sándor


Date/Time: 12 April, Friday, 14:15

Location: ELTE, TTK, Lagymanyos, 7. floor, room 7.14

Speaker: Slava Rychkov (IHES, Ecole Normale Superieure Paris)

Title: Walking, weakly first-order phase transitions, and complex CFTs

Abstract:

Most people have heard that the 2d Potts model with Q=5 states has a first 
order phase transition, but not everyone knows that the correlation length at 
this phase transition is 2500 lattice spacings. We will review "walking RG" 
behavior in gauge theories and connect it to Type II weak first-order phase 
transitions in statistical physics. Despite appearing in very different systems 
(QCD below the conformal window, the Potts model, deconfined criticality) these 
two phenomena both imply approximate scale invariance in a range of energies 
and have the same RG interpretation: a flow passing between pairs of fixed 
point at complex coupling, dubbed "complex CFTs". Observables of the real 
walking theory are approximately computable by perturbing the complex CFTs. The 
general mechanism will be illustrated by a specific and computable example: the 
two-dimensional Q-state Potts model with Q > 4. Based on 1807.11512 and 
1808.04380.