paper

Fusion and (non)-rigidity of Virasoro Kac modules in logarithmic minimal models at -central charge

arXiv:2302.08907 · doi:10.1088/1402-4896/ad23aa

Abstract

Let be the category of finite-length modules for the Virasoro Lie algebra at central charge whose composition factors are irreducible quotients of reducible Verma modules. For any , this category admits the vertex algebraic braided tensor category structure of Huang, Lepowsky, and Zhang. Here, we begin the detailed study of where for relatively prime integers ; in conformal field theory, corresponds to a logarithmic extension of the central charge Virasoro minimal model. We particularly focus on the Virasoro Kac modules , , in defined by Morin-Duchesne, Rasmussen, and Ridout, which are finitely-generated submodules of Feigin-Fuchs modules for the Virasoro algebra. We prove that is rigid and self-dual when and , but that not all are rigid when or . That is, is not a rigid tensor category. We also show that all Kac modules and all simple modules in are homomorphic images of repeated tensor products of and , and we determine completely how and tensor with Kac modules and simple modules in . In the process, we prove some fusion rule conjectures of Morin-Duchesne, Rasmussen, and Ridout.

55 pages, final version incorporating referee comments

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