Two-form gauge field
= Two-form gauge field
{title2=$B\mapsto B+d\alpha$}
An antisymmetric tensor potential $B$ has gauge transformation $B\mapsto B+d\alpha$, where $\alpha$ is a one-form. Its field strength is the three-form $H=dB$, invariant because $d^2=0$. The <Kalb–Ramond field> is the string-theory example.