NS–NS_sector
Kalb–Ramond field
Two-form field
In theoretical physics in general and string theory in particular, the Kalb–Ramond field (named after Michael Kalb and Pierre Ramond),[1] also known as the Kalb–Ramond B-field[2] or Kalb–Ramond NS–NS B-field,[3] is a quantum field that transforms as a two-form, i.e., an antisymmetric tensor field with two indices.[1][4]
The adjective "NS" reflects the fact that in the RNS formalism, these fields appear in the NS–NS sector in which all vector fermions are anti-periodic. Both uses of the word "NS" refer to André Neveu and John Henry Schwarz, who studied such boundary conditions (the so-called Neveu–Schwarz boundary conditions) and the fields that satisfy them in 1971.[5]