A note on the Green-Schwarz mechanism in open-string theories

Abstract

An interesting feature of some open superstring models in D < 10 is the simultaneous presence, in the spectrum, of gauge fields and of a number of antisymmetric tensor fields. In these cases the Green-Schwarz mechanism can (and does) take a generalized form, resulting from the combined action of all the antisymmetric tensors. These novelties are illustrated referring to some simple rational models in six dimensions, and some of their implications for the low-energy effective field theory are pointed out.

Type-I strings on magnetised orbifolds and brane transmutation

“…In general, these vacua correspond to supergravity models frozen in phases of broken supersymmetry, where the presence of (lower-dimensional) non-supersymmetric couplings renders the field equations naively inconsistent, in complete analogy with ordinary gauge theories frozen in a Higgs phase. Although similar features were previously met in the anomalous Green-Schwarz couplings of [27], the peculiar supergravity models resulting from "brane supersymmetry breaking" clearly deserve further investigation.…”

“…These configurations present another interesting novelty: they have generalised GreenSchwarz couplings [26,27] involving gauge fields and untwisted R-R forms, of the type…”

D‐branes in Standard Model building, gravity and cosmology

“…G α Gravitational and U(1) anomalies have a similar structure [115]. In six dimensions there are two distinct U(1)/non-abelian mixed anomalies.…”

“…In heterotic N=1 vacua there is a unique anomalous U(1) and its anomalies are cancelled by the universal two-index anti-symmetric tensor. In the type-I vacua, we may have several anomalous U(1)s and in four-dimensional compactifications their anomalies are cancelled by a combination of RR untwisted and twisted axions [115,116].…”

“…Moreover, the available form gauge fields to cancel the anomalies are (up to duality) pseudo-scalars (axions) and two-index antisymmetric tensors (of which typically there are plenty in six-dimensional vacua) [115,125].…”