Gravity as a quantum effect on quantum spacetime
Abstract
The 3+1dimensional EinsteinHilbert action is obtained from the 1loop effective action on noncommutative branes in the IIB or IKKT matrix model. The presence of compact fuzzy extra dimensions K as well as maximal supersymmetry of the model is essential. The EH action can be interpreted as interaction of K with the spacetime brane via IIB supergravity, and the effective Newton constant is determined by the KaluzaKlein scale of K. The classical matrix model defines a pregravity action with 2 derivatives less than the induced EH action, governing the cosmological regime. The perturbative physics is confined to the spacetime brane, which for covariant quantum spacetimes includes all dof of gravity, as well as a tower of higherspin modes. The vacuum energy of the background is given in terms of the symplectic volume form, and hence does not act as cosmological constant.
 Publication:

Physics Letters B
 Pub Date:
 April 2022
 DOI:
 10.1016/j.physletb.2022.136946
 arXiv:
 arXiv:2110.03936
 Bibcode:
 2022PhLB..82736946S
 Keywords:

 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology
 EPrint:
 6 pages. V2: dilaton contribution corrected, references added, published version