can anyone help me with finding the appropriate notion of a gauge
transformation on a gerbe (abelian or not)? I would be interested in
particular in lifting gerbes. I tried to find it several times but did
not succeed. My guess would be to define it as a vertical 2-bundle
automorphismsm of the corresponding 2-bundle, but I did not find this
mentioned anywhere... Accordingly, gauge transformations would build
up a 2-group rather than a group.
Thanks for any suggestions,