Light Fermions and the Swampland

Abstract: Quantum gravity can have important implications for Particle Physics and Cosmology. We consider constraints on D-dimensional theories in Minkowski, dS and AdS backgrounds in the light of AdS swampland conjectures as applied to their compactication in a circle. In particular, we consider the non-SUSY AdS instability conjecture and the AdS distance conjecture. For Minkowski and dS vacua the results may be summarized by a light fermion conjecture which states that in theories with a positive first non-vanishing supertrace $(-1)^{k+1}Str(M^{2k}) > 0$, a surplus of light fermions with mass $m_f < \Lambda_D^{1/D}$ must be present, where $\Lambda_D$ is the cosmological constant. The case of AdS can be made consistent with the mild but not the strong version of the AdS Distance conjecture. I will also apply the above constraints to the Standard Model of particle physics, obtaining that it would be inconsistent in Minkowski space but consistent in dS if the lightest neutrino is Dirac and lighter than the cosmological constant scale. This may shed some light into the naturalness issues observed in our universe.

general relativity and quantum cosmologyHEP - phenomenologyHEP - theorymathematical physicsquantum physics

Audience: researchers in the topic

HEP seminars TU Wien (Vienna)

Series comments: ID number: 954 8284 9369