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Research and Instruction in String Theory

Grant number: 99/12763-0
Support type:Research Projects - Thematic Grants
Duration: June 01, 2000 - July 31, 2004
Field of knowledge:Physical Sciences and Mathematics - Physics
Principal Investigator:Nathan Jacob Berkovits
Grantee:Nathan Jacob Berkovits
Home Institution: Instituto de Física Teórica (IFT). Universidade Estadual Paulista (UNESP). Campus de São Paulo. São Paulo , SP, Brazil
Associated scholarship(s):00/10245-0 - Low-energy equations of the superstring, BP.PD

Abstract

Obtaining a unified description of all of the fundamental forces of nature is an old dream of theoretical physicists. At the present time, superstring theory is the only consistent quantum-mechanical model for describing particles with gravitational and Yang-Mills interactions. All other attempts to unify these forces suffer from quantum-mechanical divergences in scattering amplitudes that cannot be removed by renormalization. Even if superstring theory is not the final theory of unification, it probably contains some essential ingredients of such a theory.Although superstring theory exists since 1972, until recently, the only available method for studying superstrings used perturbative techniques. These techniques were useful for studying scattering amplitudes of gravitons, but were useless for studying non-perturbative gravitational phenomena such as black boles. However, in 1994, a symmetry of superstring theory was discovered which relates the theory at strong and weak coupling. This symmetry was called S-duality, and is similar to the Montonen-Olive duality symmetry that relates super-Yang-Mills theory at strong and weak coupling. One ingredient of superstrings that is crucial for the absence of divergences and the existence of S-duality is spacetime supersymmetry. Nevertheless, in the usual Ramond-Neveu-Schwarz (RNS) formalism for the superstring, the effects of spacetime supersymmetry are extremely difficult to analyze. Although there exists an alternative Green-Schwarz (GS) formalism for the superstring where spacetime supersymmetry is manifest, the Green-Schwarz formalism can only be quantized in light-cone gauge which greatly reduces its usefulness. During the last ten years, my research has concentrated on understanding the roleof spacetime supersymmetry in the superstring. This research led rae to discover a new formalism for the superstring where spacetime supersymmetry is manifest and which can be quantized in covariant gauges. Because ít does not suffer from the problems of the RNS and GS formalisms, this new formalism is useful for studying the absence of divergences and the S-duality symmetry of the superstring... (AU)

Articles published in Agência FAPESP Newsletter about the research grant
Brazilian scientist makes key contributions to advances in superstring theory  

Scientific publications (7)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BERKOVITS‚ N. Covariant multiloop superstring amplitudes. COMPTES RENDUS PHYSIQUE, v. 6, n. 2, p. 185-197, 2005.
BERKOVITS‚ N. Alternative string theory in twistor space for N= 4 super-Yang-Mills theory. Physical Review Letters, v. 93, n. 1, p. 11601, 2004.
NATHAN BERKOVITS. Theoretical motivation for studying superstrings. Brazilian Journal of Physics, v. 34, n. 4a, p. 1327-1329, Dez. 2004.
BERKOVITS‚ N.; CARLINI VALLILO‚ B. One-loop< i> N-point superstring amplitudes with manifest< i> d= 4 supersymmetry. Nuclear Physics B, v. 624, n. 1, p. 45-62, 2002.
BERKOVITS‚ N.; HOWE‚ P. Ten-dimensional supergravity constraints from the pure spinor formalism for the superstring. Nuclear Physics B, v. 635, n. 1, p. 75-105, 2002.
BERKOVITS‚ N.; CHANDÍA‚ O. Lorentz invariance of the pure spinor BRST cohomology for the superstring. Physics Letters B, v. 514, n. 3, p. 394-400, 2001.
BERKOVITS‚ N.; GUKOV‚ S.; VALLILO‚ B.C. Superstrings in 2D backgrounds with R-R flux and new extremal black holes. Nuclear Physics B, v. 614, n. 1, p. 195-232, 2001.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.
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