Type IIB S-duality Research Articles

QCD3 with two-index quarks, mirror symmetry, and fivebrane anti-BIons near orientifolds

We consider a non-supersymmetric Hanany-Witten type IIB brane configuration that realises a three dimensional USp(2N) gauge theory with quarks in the two-index antisymmetric representation and SO(4) flavour symmetry. Using type IIB S-duality we find the mirror dual, an SO(2N-1) field theory with scalars in the antisymmetric representation. Analysing the magnetic dual we study the vacuum structure of the USp(2N) model and propose that the SO(4) global symmetry is unbroken. In order to support our proposal we present an SO(4) symmetric BIon configuration that describes anti-D3 branes polarising into fivebranes in the S-dual Hanany-Witten setup. We also comment on dynamical flavour symmetry breaking in other QCD3 theories with quarks in two-index representations.

Duality group actions on fermions

In this short paper we look at the action of T-duality and string duality groups on fermions, in maximally-supersymmetric theories and related theories. Briefly, we argue that typical duality groups such as SL(2,Z) have sign ambiguities in their actions on fermions, and propose that pertinent duality groups be extended by Z_2, to groups such as the metaplectic group. Specifically, we look at duality groups arising from mapping class groups of tori in M theory compactifications, T-duality, ten-dimensional type IIB S-duality, and (briefly) four-dimensional N=4 super Yang-Mills, and in each case, propose that the full duality group is a nontrivial Z_2 extension of the duality group acting on bosonic degrees of freedom, to more accurately describe possible actions on fermions. We also walk through U-duality groups for toroidal compactifications to nine, eight, and seven dimensions, which enables us to perform cross-consistency tests of these proposals.

3d N $$ \mathcal{N} $$ = 2 mirror symmetry, pq-webs and monopole superpotentials

D3 branes stretching between webs of (p,q) 5branes provide an interesting class of 3d N=2 theories. For generic pq-webs however the low energy field theory is not known. We use 3d mirror symmetry and Type IIB S-duality to construct Abelian gauge theories corresponding to D3 branes ending on both sides of a pq-web made of many coincident NS5's intersecting one D5. These theories contain chiral monopole operators in the superpotential and enjoy a non trivial pattern of global symmetry enhancements. In the special case of the pq-web with one D5 and one NS5, the 3d low energy SCFT admits three dual formulations. This triality can be applied locally inside bigger quiver gauge theories. We prove our statements using partial mirror symmetry `a la Kapustin-Strassler, showing the equality of the S^3_b partition functions and studying the quantum chiral rings.

More dual fluxes and moduli fixing

We generalize the recent proposal that invariance under T-duality leads to additional non-geometric fluxes required so that superpotentials in type IIA and type IIB orientifolds match. We show that invariance under type IIB S-duality requires the introduction of a new set of fluxes leading to further superpotential terms. We find new classes of N=1 supersymmetric Minkowski vacua based on type IIB toroidal orientifolds in which not only dilaton and complex moduli but also Kahler moduli are fixed. The chains of dualities relating type II orientifolds to heterotic and M-theory compactifications suggests the existence of yet further flux degrees of freedom. Restricting to a particular type IIA/IIB or heterotic compactification only some of these degrees of freedom have a simple perturbative and/or geometric interpretation.

Ghost D-branes

We define a ghost D-brane in superstring theories as an object that cancels the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N|M) arise as gauge symmetries in the supersymmetric world-volume theory of D-branes and ghost D-branes. A system with a pair of D-brane and ghost D-brane located at the same location is physically equivalent to the closed string vacuum. When they are separated, the system becomes a new brane configuration. We generalize the type I/heterotic duality by including n ghost D9-branes on the type I side and by considering the heterotic string whose gauge group is OSp(32+2n|2n). Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also find type II-like closed superstrings with U(n|n) gauge symmetry.

Covariant multiloop superstring amplitudes

In this article, the multiloop amplitude prescription using the super-Poincaré invariant pure spinor formalism for the superstring is reviewed. Unlike the RNS prescription, there is no sum over spin structures and surface terms coming from the boundary of moduli space can be ignored. Massless N-point multiloop amplitudes vanish for N < 4 , which implies (with two mild assumptions) the perturbative finiteness of superstring theory. Also, R 4 terms receive no multiloop contributions in agreement with the Type IIB S-duality conjecture of Green and Gutperle. To cite this article: N. Berkovits, C. R. Physique 6 (2005).

Multiloop Amplitudes and Vanishing Theorems using the Pure Spinor Formalism for the Superstring

A ten-dimensional super-Poincare covariant formalism for the superstring was recently developed which involves a BRST operator constructed from superspace matter variables and a pure spinor ghost variable. A super-Poincare covariant prescription was defined for computing tree amplitudes and was shown to coincide with the standard RNS prescription. In this paper, picture-changing operators are used to define functional integration over the pure spinor ghosts and to construct a suitable $b$ ghost. A super-Poincare covariant prescription is then given for the computation of N-point multiloop amplitudes. One can easily prove that massless N-point multiloop amplitudes vanish for N<4, confirming the perturbative finiteness of superstring theory. One can also prove the Type IIB S-duality conjecture that $R^4$ terms in the effective action receive no perturbative contributions above one loop.

D-instantons and asymptotic geometries

The large-N limit of D-3-branes is expected to correspond to a superconformal field theory living on the boundary of the anti-de Sitter space appearing in the near-horizon geometry. Dualizing the D-3-brane to a D-instanton, we show that this limit is equivalent to a type IIB S-duality. In both cases one effectively reaches the near-horizon geometry. This provides an alternative approach to an earlier derivation of the same result that makes use of the properties of a gravitational wave instead of the D-instanton.

Conformal compensators and manifest type IIB S-duality

Using the conformal compensator superfields of N=2 D=4 supergravity, the Type IIB S-duality transformations are expressed as a linear rotation which mixes the compensator and matter superfields. The classical superspace action for D=4 compactifications of Type IIB supergravity is manifestly invariant under this transformation. Furthermore, the introduction of conformal compensators allows a Fradkin-Tseytlin term to be added to the manifestly SL(2,Z)-covariant sigma model action of Townsend and Cederwall.