Gravity in 2T-Physics

The field theoretic action for gravitational interactions in d+2 dimensions is constructed in the formalism of 2T-physics. General Relativity in d dimensions emerges as a shadow of this theory with one less time and one less space dimensions. The gravitational constant turns out to be a shadow of a dilaton field in d+2 dimensions that appears as a constant to observers stuck in d dimensions. If elementary scalar fields play a role in the fundamental theory (such as Higgs fields in the Standard Model coupled to gravity), then their shadows in d dimensions must necessarily be conformal scalars. This has the physical consequence that the gravitational constant changes at each phase transition (inflation, grand unification, electro-weak, etc.), implying interesting new scenarios in cosmological applications. The fundamental action for pure gravity, which includes the spacetime metric, the dilaton and an additional auxiliary scalar field all in d+2 dimensions with two times, has a mix of gauge symmetries to produce appropriate constraints that remove all ghosts or redundant degrees of freedom. The action produces on-shell classical field equations of motion in d+2 dimensions, with enough constraints for the theory to be in agreement with classical General Relativity in d dimensions. Therefore this action describes the correct classical gravitational physics directly in d+2 dimensions. Taken together with previous similar work on the Standard Model of particles and forces, the present paper shows that 2T-physics is a general consistent framework for a physical theory.Comment: 24 pages, revision includes minor corrections and additional clarifying materia

Duality Covariant Type IIB Supersymmetry and Nonperturbative Consequences

Type-IIB supersymmetric theories have an SL(2,Z) invariance, known as U-duality, which controls the non-perturbative behavior of the theory. Under SL(2,Z) the supercharges are doublets, implying that the bosonic charges would be singlets or triplets. However, among the bosonic charges there are doublet strings and doublet fivebranes which are in conflict with the doublet property of the supercharges. It is shown that the conflict is resolved by structure constants that depend on moduli, such as the tau parameter, which transform under the same SL(2,Z). The resulting superalgebra encodes the non-perturbative duality properties of the theory and is valid for any value of the string coupling constant. The usefulness of the formalism is illustrated by applying it to purely algebraic computations of the tension of (p,q) strings, and the mass and entropy of extremal blackholes constructed from D-1-branes and D-5-branes. In the latter case the non-perturbative coupling dependence of the BPS mass and metric is computed for the first time in this paper. It is further argued that the moduli dependence of the superalgebra provides hints for four more dimensions beyond ten, such that the superalgebra is embedded in a fundamental theory which would be covariant under SO(11,3). An outline is given for a matrix theory in 14 dimensions that would be consistent with M(atrix) theory as well as with the above observations.Comment: RevTeX, 10 page

The Standard Model as a 2T-physics Theory

New developments in 2T-physics, that connect 2T-physics field theory directly to the real world, are reported in this talk. An action is proposed in field theory in 4+2 dimensions which correctly reproduces the Standard Model (SM) in 3+1 dimensions (and no junk). Everything that is known to work in the SM still works in the emergent 3+1 theory, but some of the problems of the SM get resolved. The resolution is due to new restrictions on interactions inherited from 4+2 dimensions that lead to some interesting physics and new points of view not discussed before in 3+1 dimensions. In particular the strong CP violation problem is resolved without an axion, and the electro-weak symmetry breakdown that generates masses requires the participation of the dilaton, thus relating the electro-weak phase transition to other phase transitions (such as evolution of the universe, vacuum selection in string theory, etc.) that also require the participation of the dilaton. The underlying principle of 2T-physics is the local symmetry Sp(2,R) under which position and momentum become indistinguishable at any instant. This principle inevitably leads to deep consequences, one of which is the two-time structure of spacetime in which ordinary 1-time spacetime is embedded. The proposed action for the Standard Model in 4+2 dimensions follows from new gauge symmetries in field theory related to the fundamental principles of Sp(2,R). These gauge symmetries thin out the degrees of freedom from 4+2 to 3+1 dimensions without any Kaluza-Klein modes.Comment: 6 pages, to appear in the proceedings of "SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions