Disformal transformations on the CMB

作者：Burrage Clare^*; Cespedes Sebastian; Davis Anne Christine

来源：Journal of Cosmology and Astroparticle Physics, 2016, 2016(8): 024.

DOI：10.1088/1475-7516/2016/08/024

• primordial gravitational waves (theory)
• inflation
• modified gravity
• CMBR theory

Inthis work we study the role of disformal transformation on cosmological backgrounds and its relation to the speed of sound for tensor modes. A speed different from one for tensor modes can arise in several contexts, such as Galileons theories or massive gravity, nevertheless the speed is very constrained to be one by observations of gravitational wave emission. It has been shown that in inflation a disformal transformation allows to set the speed for tensor modes to one without making changes to the curvature power spectrum. Here we show that this invariance does not hold when considering the CMS anisotropy power spectrum. It turns out that the after doing the transformation there is an imprint on the acoustic peaks and the diffusion damping. This has interesting consequences; here we explore quartic galileon theories which allow a modified speed for tensor modes. For these theories the transformation can be used to constraint the parameter space in different regimes.

• 出版日期2016-8