Journal of Noncommutative Geometry


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Volume 12, Issue 4, 2018, pp. 1359–1424
DOI: 10.4171/JNCG/310

Published online: 2018-12-06

Open-closed modular operads, the Cardy condition and string field theory

Martin Doubek and Martin Markl[1]

(1) Czech Academy and Charles University, Prague, Czechia

We prove that the modular operad of diffeomorphism classes of Riemann surfaces with both “open” and “closed” boundary components, in the sense of string field theory, is the modular completion of its genus 0 part quotiented by the Cardy condition. We also provide a finitary presentation of a version of this modular two-colored operad and characterize its algebras via morphisms of Frobenius algebras, recovering some previously known results of Kaufmann, Penner and others. As an important auxiliary tool we characterize inclusions of cyclic operads that induce inclusions of their modular completions.

Keywords: Modular completion, hybrid, open and closed strings, Frobenius algebra

Doubek Martin, Markl Martin: Open-closed modular operads, the Cardy condition and string field theory. J. Noncommut. Geom. 12 (2018), 1359-1424. doi: 10.4171/JNCG/310