Abelian p-form gauge field ($F_{p+1}=d{A}_p$)

An Abelian $p$-form gauge potential $A_p$ is an antisymmetric tensor field with gauge equivalence $A_p\mapsto A_p+d{\Lambda }_{p-1}$ and field strength $F_{p+1}=d{A}_p$. Its field strength obeys the Bianchi identity for an Abelian p-form. The potential can have global gauge data even when its local field strength vanishes.

A massless Abelian $p$-form in $D$-dimensional flat spacetime transforms on shell as an antisymmetric rank-$p$ tensor of the rotational little group $SO(D-2)$. Its physical state count is $\left(\genfrac{}{}{0ex}{}{D-2}{p}\right)$. A compatible real self-duality constraint halves this count. A four-dimensional three-form has no local propagating polarization.

A three-form potential in four dimensions has no local massless polarizations. Its four-form field strength can be a constant multiple of the spacetime volume form. The equation $d(g_3^{-2}\ast F_4)=0$ leaves a constant flux parameter, which can affect vacuum energy despite supplying no local wave.

Locally in four dimensions, a massless two-form is dual to one real scalar field. In signature $(-+++)$, the first-order density $-H^2/(12g_B^2)+{ϵ}^{\mu \nu \rho \sigma }{H}_{\mu \nu \rho }{\partial }_{\sigma }a/6$ gives $H^{\mu \nu \rho }=g_B^2{ϵ}^{\mu \nu \rho \sigma }{\partial }_{\sigma }a$. Eliminating $H$ in both terms produces $-g_B^2(\partial a{)}^2/2$, so the fixed-normalization kinetic coefficient is inverted. Global flux sectors and scalar periodicities need separate treatment.

For an Abelian p-form gauge field with local field strength $F=dA$, the exterior derivative identity $d^2=0$ gives $dF=0$. In a first-order duality formulation, this identity can be enforced with a Lagrange multiplier, whose elimination restores the local gauge potential.