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A scale invariant Goldstino theory coupled to Supergravity is obtained as a standard supergravity dual of a rigidly scale invariant higher--curvature Supergravity with a nilpotent chiral scalar curvature. The bosonic part of this theory describes a massless scalaron and a massive axion in a de Sitter Universe., Comment: CERN-PH-TH-2015-193. Misprints corrected. Final version to appear in Phys. Lett. B

We show how allowing non-local terms in the field equations of symmetric tensors uncovers a neat geometry that naturally generalizes the Maxwell and Einstein cases. The end results can be related to multiple traces of the generalized Riemann curvatures R_{alpha_1 ... alpha_s; beta_1 > ... beta_s} introduced by de Wit and Freedman, divided by suitable powers of the D'Alembertian operator \Box. The conventional local equations can be recovered by a partial gauge fixing involving the trace of the gauge parameters Lambda_{alpha_1 ... alpha_{s-1}}, absent in the Fronsdal formulation. The same geometry underlies the fermionic equations, that, for all spins s+(1/2), can be linked via the operator (not hskip 1pt pr)/(\Box) to those of the spin-s bosons., References and comment added. Final version to appear in Physics Letters B

We extend the construction of open descendants to the $SU(2)$ WZW models with non-diagonal left-right pairing, namely $E_7$ and the $D_{odd}$ series in the $ADE$ classification of Cappelli, Itzykson and Zuber. The structure of the resulting models is determined to a large extent by the ``crosscap constraint'', while their Chan-Paton charge sectors may be embedded in a general fashion into those of the corresponding diagonal models., 14 pages, latex, 1 figure

We show how to generalize the $SU(2)$ WZW models to allow for open and unoriented sectors. The construction exhibits some novel patterns of Chan-Paton charge assignments and projected spectra that reflect the underlying current algebra., 13 pages, latex, 1 figure.

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., 13 pages, phyzzx

We present a first instance of an exact supersymmetric string vacuum in curved space-time. It corresponds to the Freedman-Gibbons electrovac solution to one version of N =4 supergravity, with N =2 space-tme supersymmetry. The conformal theory includes a Wess-Zumino-Witten model on the SU (1,1) group manifold.

The correspondence between free second quantized and first quantized theories implies that the equation of motion of any free string field theory is Q Φ = 0. The string have a fields have a fixed, but not unique, total ghost number. In most cases the equations of motion do not follow from lagrangians. It is noted that Witten's interacting theory should also only be used for equations of motion. Gauge fixing and the reduction of strings to physical states are studied in detail.

We construct a supergravity model whose scalar degrees of freedom arise from a chiral superfield and are solely a scalaron and an axion that is very heavy during the inflationary phase. The model includes a second chiral superfield X , which is subject however to the constraint X2=0 so that it describes only a Volkov–Akulov goldstino and an auxiliary field. We also construct the dual higher-derivative model, which rests on a chiral scalar curvature superfield R subject to the constraint R2=0 , where the goldstino dual arises from the gauge-invariant gravitino field strength as γmnDmψn . The final bosonic action is an R+R2 theory involving an axial vector Am that only propagates a physical pseudoscalar mode.

We discuss the partition function of the SO(8192) bosonic string at arbitrary genus. As in the genus-one case, diagrams defined in terms of involutions acting in the same way on the homology basis are weighted by identical mulitplicity factors. This property emerges as the basis feature of the SO(8192) theory. It corresponds to the picture of this model as a parameter-space orbifold of the closed bosonic string. By factorization we recover amplitudes in the degenerate limit.

We add D fermionic variables to the ends of open strings, generating the combinatoric and group theory factors of SO(2[D/2]). Thus 10 variables give SO(32). The results are illustrated by a one-loop calculation, giving the partition function of the theory. We discuss boundary conditions, and the modifications of the Feynman rules needed for obtaining the groups U(2 [ D 2 ] ) and USp(2 [ D 2 ] ) .

At genus greater than one, the surfaces contributing to open-string partition functions admit the action of a non-trivial subgroup of Sp (2 g , Z ). The “relative modular group” is not solely associated with modular-invariant closed-string subdiagrams. In particular, at genus two, combining the degeneration of dividing channels with the action of this group leads to spin-statistics restrictions for open strings, in complete analogy with the closed-string case. In addition, it shows that only totally-left-right symmetric closed-string models may descend to open-string ones, and essentially induces the GSO-like projections in the open and unoriented channels.

We show that the S matrix of pure Einstein gravity diverges at the two-loop order in four dimensions.

A set of conditions expressing tree-level unitarity in the theory of open superstrings has recently been formulated by Schwarz. His conjecture that the Yang-Mills gauge group must be a classical group, with the massless particles in the adjoint representation, is proved in detail. It is also shown how the representations of the massive states are classified in each one.