We construct a class of analytic solutions of WZW-type open superstring field theory describing marginal deformations of a reference D-brane background. The deformations we consider are generated by on-shell vertex operators with vanishing operator products. The superstring solution exhibits an intriguing duality with the corresponding marginal solution of the bosonic string. In particular, the...

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 equations of motion written in superspace for the background fields coupled to the superstring. The second application is related to the BRST invariance of ...

It was previously shown that most of the superstrings can be obtained from those with higher world-sheet supersymmetry as spontaneously broken phases. In this paper, we show that the small N = 4 superstring, which was left out of this hierarchy of the universal string, can be obtained from the large N = 4 strings. We also show that the N = 2 string is a special vacuum of small N = 4 string. Thu...

We review and develop the formalism of ghost number cohomologies, outlined in our previous work, to classify the quantum states of M-theory.We apply this formalism to the matrix formulation of M-theory to obtain NSR superstring action from dimensionally reduced matrix model.The BPS condition of the matrix theory is related to the worldsheet reparametrizational invariance in superstring theory, ...

We review and develop the formalism of ghost number cohomologies, outlined in our previous work, to classify the quantum states of M-theory.We apply this formalism to the matrix formulation of M-theory to obtain NSR superstring action from dimensionally reduced matrix model.The BPS condition of the matrix theory is related to the worldsheet reparametrizational invariance in superstring theory, ...

Superstring theory is the only known renormalizable quantum theory of gravity, and spacetime supersymmetry plays a crucial role in removing the divergences. Spacetime supersymmetry also plays a crucial role in the recent conjectures [1] of strong-weak duality in superstring theory. However, spacetime supersymmetry is only an on-shell symmetry in the conventional N ­ 1 RamondNeveu-Schwarz (RNS) ...

I discuss gauge coupling unification in a class of superstring standard–like models, which are derived in the free fermionic formulation. Recent calculations indicate that the superstring unification scale is at O(10GeV ) while the minimal supersymmetric standard model is consistent with LEP data if the unification scale is at O(10)GeV . A generic feature of the superstring standard–like models...