# SM-GRAV

European Research Council

Advanced Investigator Grant no. 669288

## Gravity, Holography and the Standard Model

Principal Investigator: Elias Kiritsis

Participating Institutions: APC, Université Paris 7 and CCTP/ITCP, University of Crete

This Advanced ERC grant was awarded to Elias Kiritsis in order to study how holographic ideas can be used to elucidate the physics beyond the standard model and gravity. The abstract of the project SM-GRAV is as follows:

The main thrust of this project is to investigate implications of a recently discovered correspondence (string theory/gravity and gauge theory) to the physics beyond the Standard Model (SM) of fundamental interaction and its coupling to gravity. Instead of relying on the string picture of the unification of all interactions with gravity, it is proposed to look at its dual version: four-dimensional quantum field theories (QFT). Such a different perspective is expected to provide three distinct results:

- A QFT view of SM embedding in string theory
- Novel phenomena and properties of such embeddings that are hard to see in the string theory picture
- A "dual" view that would be valid in non-stringy regimes (which may be well described by QFT)

The key idea is that gravity, as observed in nature, is emergent: it is the avatar of a (hidden) large-N (near) CFT that is interacting with the SM at high energy (the Planck scale). Such an approach provides an appealing UV completion to the SM+gravity: a UV complete four-dimensional QFT. There are, however, many questions that need to be addressed in order for this setup to be a viable physical theory:

- Why is the gravitational force four-dimensional (instead of higher dimensional as suggested by standard holography)?
- Why does the coupling of the gravitational force to the SM satisfy the equivalence principle to such a high accuracy?
- Why are other gravitons, emerging from couplings to other QFTs, not visible? What are their leading effects if one wishes to look for them?
- What are other universal interactions with the SM model implied in this picture? What are their phenomenological consequences?
- How can one construct, precise and controllable models for this setup? What is the general picture of the theory landscape?
- How is Cosmology emerging in this picture? How do the important problems associated with it get resolved?

SM-GRAV will address all of the above questions using the tools of QFT, of string theory and the AdS-CFT correspondence. The outcome of the proposed research is expected to be a concrete model/scenario for the emergence and coupling of the "generalized gravitational sector fields" to the SM model and the potential novel phenomenological implications for particle physics and cosmology.

The PI of this program is Elias Kiritsis. The work will be done at APC, Universite Diderot, Paris 7 and at CCTP.