Unit:
Department of PhysicsLibrary of the School of Science
Author:
Sagkrioti Eftychia
Dissertation committee:
Σφέτσος Κωνσταντίνος, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Τετράδης Νικόλαος, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Ήργες Νικόλαος, Αναπλ. Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Σπανός Βασίλης, Αναπληρωτής Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Διαμάντης Γεώργιος, Αναπλ. Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Διάκονος Φώτιος, Αναπλ. Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Σαουλίδου Νίκη, Αναπλ. Καθηγητρια, Τμήμα Φυσικής, ΕΚΠΑ
Original Title:
Ολοκληρώσιμες δομές σε θεωρίες πεδίου και στη θεωρία χορδών και ο ρόλος των συμμετριών στην επίτευξη ακριβών υπολογισμών
Translated title:
Integrable structures in Quantum Field Theory and String Theory and the role of symmetry to exact calculations
Summary:
In the context of the present dissertation, deformations of two-dimensional Conformal Field Theories (CFTs) with specific symmetries have been studied, while emphasis was given to the study of the properties of the aforementioned theories under the Renormalization Group (RG) flow. More specifically, the so-called λ-deformed σ-models represent deformations of the Wess-Zumino-Witten (WZW) models by a set of classically marginal, bilinear in the WZW currents, operators, through a deformation matrix λ. These models, for specific choices of the matrix λ, maintain their integrability even after the deformation. Furthermore, their effective actions are endowed with a duality-type symmetry, which (for large values of the level k of the underlying Kac-Moody algebra) involves the inversion of the deformation matrix and the group element, along with the change of the sign of k. This symmetry allows the exact, with respect to the deformation parameter λ, computation of physical quantities, with minimal to no use of perturbation theory. However, all physical quantities computed for these models are still perturbative with respect to the 1/k expansion for large k. Thus, the duality-type symmetry, as described above, allows the computation of exact in λ results, but up to 1/k in the large k expansion.
In this framework, the β-functions, the anomalous dimension of operators and the central charge C-functions have been computed for various generalizations of the original λ-deformed σ-models described above, using both field theory and gravity techniques.
Main subject category:
Science
Keywords:
Renormalization Group, Discrete Symmetries, Quantum Field Theory (QFT), Conformali Field Theory (CFT), σ-models, String Theory
Number of references:
148
