Boundary Symmetry Breaking in CFT and the string order parameter

Bonsignori, Riccarda; Capizzi, Luca; Panopoulos, Pantelis (2023) Boundary Symmetry Breaking in CFT and the string order parameter. Journal of High Energy Physics, 2023 (5). ISSN 1029-8479

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Abstract

We consider the ground state of a one-dimensional critical quantum system carrying a global symmetry in the bulk, which is explicitly broken by its boundary conditions. We probe the system via a string-order parameter, showing how it detects the symmetry breaking pattern. We give a precise characterization of the mechanism depicted above in Boundary CFT, and we find a general logarithmic scaling for the order parameter. As a first example we analyze the breaking of a U(1) symmetry for complex free theories induced by a boundary pairing term. Moreover, we give predictions for the breaking of U(N) in free theories, arising from a boundary mixing. We test our predictions with numerical calculations for some lattice realizations of free fermionic system with boundary symmetry breaking, finding a good agreement.

Item Type:	Article
Uncontrolled Keywords:	Boundary Quantum Field Theory; Global Symmetries; Scale and Conformal Symmetries
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Theoretical Physics Division
Projects:	Project title Project leader Project code Project type Nove geometrije za gravitaciju i prostor-vrijeme-GRASP Athanasios Chatzistavrakidis IP-2018-01-7615 HRZZ
Depositing User:	Josipa Karadžole
Date Deposited:	14 Apr 2026 13:34
URI:	http://fulir.irb.hr/id/eprint/11707
DOI:	10.1007/JHEP05(2023)027

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