Topic: DHOST Cosmology of nonsingular Bounce  

Speaker: AMARA ILYAS  中科大博士生  

Time: 10:00, December 9, 2021

Venue: New Building N203

Abstract: DHOST theories (the maximal set of scalar-tensor theories) are generalize versions of Horndeski type in four dimensional spacetime by including all possible terms with at most three powers of second derivatives of the scalar field. The gradient instability that widely exists in nonsingular bounce cosmologies in the framework of scalar-tensor and Horndeski/Galileon theories is removed by the effects of new operators introduced by the DHOST. The DHOST bounce scenario with cosmological perturbations generated by thermal fluctuations proves to be the most efficient one, and the corresponding predictions are in perfect agreement with observational bounds.