Saha Theory Workshop: Cosmology at the Interface

A simple solution to the fine tuning problem of the cosmological constant

29 Jan 2015, 16:00

15m

3307 (SINP Phase-III, 2nd Floor)

Contributory Talks Formal/Dark Energy

Speaker

Mr GOPAL Kashyap (IIT KANPUR)

Description

We show that the fine tuning problem of the cosmological constant can be solved in a conformal model, with explicit conformal symmetry breaking. We argue that the model has two different terms which essentially contribute to the cosmological constant. A local conformal transformation leads to a cancellation of these two terms among one another. Hence these produce no physical consequence for cosmic evolution. The model generates a small cosmological constant without requiring any fine tuning.

Summary

We have presented a simple mechanism
which solves the fine tuning problem of
the cosmological constant. It is based on local conformal invariance but
also requires terms which break this symmetry.
We show that by a suitable conformal transformation we can cancel
the cosmological constant in the symmetry breaking
sector with a quadratic scalar
field term in the symmetry preserving sector. This leaves behind a
small term which effectively leads to the physical cosmological constant.
Its small value is maintained by choosing very small
parameters in the symmetry breaking sector. These do not require
fine tuning since they do not get any contribution from the symmetry
preserving sector at loop orders. The model is very economical since it only introduces
one additional real scalar, $\chi$, and the Weyl meson.
The model uses the
GR-SI prescription for renormalization. The perturbation theory in this
case is more complicated. However if we ignore the contributions due to
$\chi$ and the Weyl meson, it reduces to the standard perturbation
theory. The contributions due to $\chi$ break renormalizability
of the model. However such terms are suppressed by Planck mass and
comparable to contributions due to quantum gravity.
Hence this problem is only as serious as the problem of non-renormalizability
of gravity.
Our proposal solves the fine tuning problem of the cosmological constant
due to potentially large contributions arising from the matter fields.

Presentation materials

talk

SINP_talk.pdf