Murray, M.Roberts, D.Stevenson, D.Vozzo, R.2018-09-252018-09-252017Advances in Theoretical and Mathematical Physics, 2017; 21(4):921-9751095-07611095-0753http://hdl.handle.net/2440/114635We develop the theory of simplicial extensions for bundle gerbes and their characteristic classes with a view towards studying descent problems and equivariance for bundle gerbes. Equivariant bundle gerbes are important in the study of orbifold sigma models. We consider in detail two examples: the basic bundle gerbe on a unitary group and a string structure for a principal bundle. We show that the basic bundle gerbe is equivariant for the conjugation action and calculate its characteristic class; we show also that a string structure gives rise to a bundle gerbe which is equivariant for a natural action of the String 2-group.enCopyright status unknownJournal article003007675710.4310/ATMP.2017.v21.n4.a30004151390000032-s2.0-85030862689369211Murray, M. [0000-0003-3713-9623]Roberts, D. [0000-0002-3478-0522]Stevenson, D. [0000-0003-4399-7632]