B-field transformations of Poisson groupoids

In this work we study B-field transformations of multiplicative Poisson bivectors on a Lie groupoid G. We are concerned with B-fields given by multiplicative closed 2-forms on G. We view Poisson groupoids and their B-field symmetries as special instances of multiplicative Dirac structures. These are geometric structures that unify both multiplicative Poisson bivectors and multiplicative closed 2-forms. This allows us to extend results of Bursztyn and Radko on gauge transformations of symplectic/Poisson groupoids. We also describe B-field symmetries of Poisson groupoids at the infinitesimal level.