23 September 2021, 13:15 (EET), online seminar

• David Benisty (DAMTP, Cambridge)
• Title: The Dark side of the torsion: Dark Energy from kinetic torsion
• Abstract: An extension to the Einstein-Cartan (EC) action is discussed in terms of cosmological solutions. The torsion incorporated in the EC Lagrangian is assumed to be totally anti-symmetric, and written by of a vector S^\mu. Then this torsion model, compliant with the Cosmological Principle, is made dynamical by introducing its quadratic, totally anti-symmetric derivative. The EC Lagrangian then splits up into the Einstein-Hilbert portion and a (mass) term ∼s^2. While for the quintessence model, dark energy arises from the potential, here the kinetic term, 1/\mu^2\dot{s}^2, plays the role of dark energy. The quadratic torsion term, on the other hand, gives rise to a stiff fluid that leads to a bouncing solution. A bound on the bouncing solution is calculated.
• Based on: arXiv:2109.01052