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- Nathan Berkovits
- 2000

Using pure spinors, the superstring is covariantly quantized. For the first time, mass-less vertex operators are constructed and scattering amplitudes are computed in a manifestly ten-dimensional super-Poincaré covariant manner. Quantizable non-linear sigma model actions are constructed for the superstring in curved backgrounds, including the

- Nathan Berkovits
- 1995

Using the topological techniques developed in an earlier paper with Vafa, a field theory action is constructed for any open string with critical N=2 worldsheet superconformal invariance. Instead of the Chern-Simons-like action found by Witten, this action resembles that of a Wess-Zumino-Witten model. For the N=2 string which describes (2,2) self-dual… (More)

- Nathan Berkovits
- 1999

We review a formalism of superstring quantization with manifest six-dimensional spacetime supersymmetry, and apply it to AdS 3 × S 3 backgrounds with Ramond-Ramond flux. The resulting description is a conformal field theory based on a sigma model whose target space is a certain supergroup SU In the RNS formulation of superstring theory, powerful conformal… (More)

- Nathan Berkovits
- 2002

It has recently been shown that the ten-dimensional superstring can be quantized using the BRST operator Q = ∮ λdα where λ α is a pure spinor satisfying λγλ = 0 and dα is the fermionic supersymmetric derivative. In this paper, the pure spinor version of superstring theory is formulated in a curved supergravity background and it is shown that nilpotency and… (More)

Conformal supergravity arises in presently known formulations of twistor-string theory either via closed strings or via gauge-singlet open strings. We explore this sector of twistorstring theory, relating the relevant string modes to the particles and fields of conformal supergravity. We use the twistor-string theory to compute some tree level scattering… (More)

- Nathan Berkovits, M . Bershadsky, Slava Zhukov, Barton Zwiebach
- 1999

We quantize the superstring on the AdS2 × S background with Ramond-Ramond flux using a PSU(1, 1|2)/U(1)× U(1) sigma model with a WZ term. One-loop conformal invariance of the model is guaranteed by a general mechanism which holds for coset spaces G/H where G is Ricci-flat and H is the invariant locus of a Z4 automorphism of G. This mechanism gives conformal… (More)

- Nathan Berkovits
- 2004

A ten-dimensional super-Poincaré 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-Poincaré covariant prescription was defined for computing tree amplitudes and was shown to coincide with the standard RNS prescription. In this… (More)

- Nathan Berkovits
- 2008

In this letter, an alternative string theory in twistor space is proposed for describing perturbative N=4 super-Yang-Mills theory. Like the recent proposal of Witten, this string theory uses twistor worldsheet variables and has manifest spacetime superconformal invariance. However, in this proposal, tree-level super-Yang-Mills amplitudes come from open… (More)

- Nathan Berkovits
- 2000

A classical action for open superstring field theory has been proposed which does not suffer from contact term problems. After generalizing this action to include the non-GSO projected states of the Neveu-Schwarz string, the pure tachyon contribution to the tachyon potential is explicitly computed. The potential has a minimum of V = − 1 32g2 which is 60% of… (More)

- Nathan Berkovits
- 2005

Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are added to the pure spinor formalism for the superstring. Twisted ĉ = 3 N=2 generators are then constructed where the pure spinor BRST operator is the fermionic spin-one generator, and the formalism is interpreted as a critical topological string. Three applications of this… (More)