Torsion driving cosmic expansion
Johannes Kirsch, David Vasak, Armin van de Venn, Jürgen Struckmeier
Abstract
Abstract We study a cosmological model based on the canonical Hamiltonian transformation theory. Using a linear-quadratic approach for the free gravitational De Donder–Weyl Hamiltonian $$H_\textrm{Gr}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>H</mml:mi><mml:mtext>Gr</mml:mtext></mml:msub></mml:math> , the model contains terms describing a deformation of an AdS spacetime and a fully anti-symmetric torsion in addition to Einstein’s theory. The resulting extension of the Einstein–Cartan theory depends on two initially unknown constants, $$\Omega _\textrm{g}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Ω</mml:mi><mml:mtext>g</mml:mtext></mml:msub></mml:math> and $$\Omega _\textrm{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Ω</mml:mi><mml:mtext>s</mml:mtext></mml:msub></mml:math> . Given an appropriate choice of these parameters resulting from the analysis of asymptotics, numerical calculations were performed with $$\Omega _\mathrm {\Lambda } = 0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ω</mml:mi><mml:mi>Λ</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math> . Values from the Planck Collaboration (Aghanim in Cosmol Parameters 641 , 6, 2020) were used for all other required cosmological parameters. In this way, it is shown that torsion can explain phenomena commonly attributed to dark energy, and thus can replace Einstein’s cosmological constant.