The Reduced Tensor Product of Braided Tensor Categories Containing a Symmetric Fusion Category

Abstract: We detail a construction of a symmetric monoidal structure, called the reduced tensor product on the 2-category of braided tensor categories $\mathbf{BTC}(\mathcal{A})$ containing a fixed symmetric fusion subcategory $\mathcal{A}$. The construction only depends on the braiding and monoidal structure of the categories involved. The main tool in the construction is an enriching procedure that is shown to give an equivalence between $\mathbf{BTC}(\mathcal{A})$ and a 2-category of so-called Drinfeld centre crossed braided tensor categories. As an application of the reduced tensor product, we show that it gives a pairing between minimal modular extensions of braided tensor categories containing $\mathcal{A}$ as their transparent subcategory.