The boundary entropy function for interface conformal field theories

Afxonidis, Evangelos [Univ. of Oviedo (Spain); Univ. of Texas, Austin, TX (United States)] (ORCID:0000000160640446); Karch, Andreas [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000257252124); Murdia, Chitraang [Univ. of Pennsylvania, Philadelphia, PA (United States)] (ORCID:0000000276901521)

doi:10.1007/jhep07(2025)132

DOE OSTI · 3011748

The boundary entropy function for interface conformal field theories

Afxonidis, Evangelos [Univ. of Oviedo (Spain); Univ. of Texas, Austin, TX (United States)] (ORCID:0000000160640446)·Karch, Andreas [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000257252124)·Murdia, Chitraang [Univ. of Pennsylvania, Philadelphia, PA (United States)] (ORCID:0000000276901521)

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Abstract

In 1+1 dimensional conformal field theory with a boundary the boundary contribution to the entanglement entropy is determined by a single number g effectively counting the boundary degrees of freedom. In contrast, in 1+1 dimensional interface CFTs the corresponding quantity is a non-trivial function depending on the position of the interval relative to the interface, giving access to much more detailed information about the defect. In this work we determined this g -function in several examples using holography and derive some of its basic properties from holography and strong subadditivity.

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Afxonidis, Evangelos [Univ. of Oviedo (Spain); Univ. of Texas, Austin, TX (United States)] (ORCID:0000000160640446), Karch, Andreas [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000257252124), Murdia, Chitraang [Univ. of Pennsylvania, Philadelphia, PA (United States)] (ORCID:0000000276901521). 2025-07-10. The boundary entropy function for interface conformal field theories. https://doi.org/10.1007/jhep07(2025)132

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