News Update on Theory of Gravity : March – 2020

Kodaira-Spencer theory of gravity and exact results for quantum string amplitudes

We develop techniques to compute higher loop string amplitudes for twistedN=2 theories withĉ=3 (i.e. the critical case). An important ingredient is the discovery of an anomaly at every genus in decoupling of BRST trivial states, captured to all orders by a master anomaly equation. [1]

Reconstruction of a Scalar-Tensor Theory of Gravity in an Accelerating Universe

The present acceleration of the Universe strongly indicated by recent observational data can be modeled in the scope of a scalar-tensor theory of gravity. We show that it is possible to determine the structure of this theory along with the present density of dustlike matter from two observable cosmological functions: the luminosity distance and the linear density perturbation in the dustlike matter component as functions of redshift. [2]

Eddington’s Theory of Gravity and Its Progeny

We resurrect Eddington’s proposal for the gravitational action in the presence of a cosmological constant and extend it to include matter fields. We show that the Newton-Poisson equation is modified in the presence of sources and that charged black holes show great similarities with those arising in Born-Infeld electrodynamics coupled to gravity. [3]

Bianchi Type-IX Cosmological Model with a Perfect Fluid in f(R) Theory of Gravity

Bianchi type-IX space-time is considered in the framework of the ƒ(R) theory of gravity when the source of the energy momentum tensor is a perfect fluid. The cosmological model is obtained by using the condition that the expansion scalar (θ) is proportional to the shear scalar (σ). The physical and geometrical properties of the model are also discussed. [4]

Plane Symmetric Vacuum Cosmological Model with a Special form of Deceleration Parameter in ƒ(R) Theory of Gravity

In this paper we have obtained vacuum solutions of the plane symmetric space-time in ƒ(R) gravity. The general solutions of the field equations of plane symmetric space-time have been obtained under the assumption of special form of deceleration parameter. The physical and geometrical aspect of the model is also discussed. [5]

Reference

[1] Bershadsky, M., Cecotti, S., Ooguri, H. and Vafa, C., 1994. Kodaira-Spencer theory of gravity and exact results for quantum string amplitudes. Communications in Mathematical Physics165(2), pp.311-427.

[2] Boisseau, B., Esposito-Farese, G., Polarski, D. and Starobinsky, A.A., 2000. Reconstruction of a scalar-tensor theory of gravity in an accelerating universe. Physical Review Letters85(11), p.2236.

[3] Banados, M. and Ferreira, P.G., 2010. Eddington’s theory of gravity and its progeny. Physical review letters105(1), p.011101.

[4] R. Ghate, H. and S. Sontakke, A. (2015) “Bianchi Type-IX Cosmological Model with a Perfect Fluid in f(R) Theory of Gravity”, Physical Science International Journal, 7(3), pp. 214-222. doi: 10.9734/PSIJ/2015/18515.

[5] B. Raut, V., S. Adhav, K. and K. Joshi, D. (2014) “Plane Symmetric Vacuum Cosmological Model with a Special form of Deceleration Parameter in ƒ(R) Theory of Gravity”, Physical Science International Journal, 5(1), pp. 74-80. doi: 10.9734/PSIJ/2015/13999.

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