Related papers: Lorentz-Covariant Green-Schwarz Superstring Amplit…
We analyze an alternative prescription for computing tree level scattering amplitudes in the pure spinor superstring. Proposed by Berkovits, and inspired by an earlier work by Lee and Siegel, it bypasses the traditional ghost number three…
An exact renormalization group equation is written down for the world sheet theory describing the bosonic open string in general backgrounds. Loop variable techniques are used to make the equation gauge invariant. This is worked out…
A covariant path integral calculation of the even spin structure contribution to the one-loop N-graviton scattering amplitude in the type-II superstring theory is presented. The apparent divergence of the $N=5$ amplitude is resolved by…
We prove the formula for the complete tree-level $S$-matrix of $\mathcal{N}=8$ supergravity recently conjectured by two of the authors. The proof proceeds by showing that the new formula satisfies the same BCFW recursion relations that…
We exploit the tree level bosonic 4-particle scattering amplitudes in D=11 supergravity to construct the bosonic part of a linearized supersymmetry-, coordinate- and gauge-invariant. By differentiation, this invariant can be promoted to be…
We give a comprehensive review of recent developments on using the pure spinor formalism to compute massless superstring scattering amplitudes at tree level. The main results of the pure spinor computations are placed into the context of…
Employing the string bit formalism of hep-th/0209215, we identify the basis transformation that relates BMN operators in N=4 gauge theory to string states in the dual string field theory at finite g_2=J^2/N. In this basis, the supercharge…
In this note, we first explain the equivalence between the interaction Hamiltonian of Green-Schwarz light-cone gauge superstring field theory and the twist field formalism known from matrix string theory. We analyze the role of the large N…
The main goal of this paper is the manifestly covariant derivation of the classical relation between the gauge-fixed Grassmann variables of the NSR string and the Type II GS superstring. To this end we analyze the superembedding equation…
A supersymmetric Lorentz invariant mechanism for superspace deformations is proposed. It is based on an extension of superspace by one $\lambda_{a}$ or several Majorana spinors associated with the Penrose twistor picture. Some examples of…
The covariant and kappa-symmetric action for superstring in direct product of two flat D=10 N=1 superspaces is presented. It is given by the sum of supersymmetric generalization of two copies of chiral boson actions constructed with the use…
In this thesis are presented two aplications of the sigma model for the superstring in the pure spinor formulation. The first aplication concerns the computation of the one-loop conformal invariance for the type II superstring, resulting in…
We study the twisted version of the supersymmetric $G/T=SU(n)/U(1)^{\otimes(n-1)} gauged Wess-Zumino-Witten model. By studying its fixed points under BRST transformation this model is shown to be reduced to a simple topological field…
We formulate Lorentz-covariant classical perturbation theory to deal with relativistic bremsstrahlung under gravitational scattering. Our approach is a version of the fast motion approximation scheme, the main novelty being the use of the…
We extend to a general class of covariant gauges an approach which relates the thermal Green functions to forward scattering amplitudes of thermal particles. A brief discussion of the non-transversality of the thermal gluon polarization…
We propose a modification of the Sp(2) covariant superfield quantization to realize a superalgebra of generating operators isomorphic to the massless limit of the corresponding superalgebra of the osp(1,2) covariant formalism. The modified…
We show that certain heterotic string amplitudes are given in terms of correlators of the twisted topological (2,0) SCFT, corresponding to the internal sector of the N=1 spacetime supersymmetric background. The genus g topological partition…
I give an overview of open, closed and heterotic N=2 strings. At the tree level I derive the effective field theories of all the strings, and discuss the group theory of the N=2 open string and the interaction between its open and closed…
High energy fixed angle scattering is studied in matrix string theory. The saddle point world sheet configurations, which give the dominant contributions to the string theory amplitude, are taken as classical backgrounds in matrix string…
For the gauge couplings, which arise after toroidal compactification of six-dimensional heterotic N=1 string theories from the T^2 torus, we calculate their one-loop corrections. This is performed by considering string amplitudes involving…