Large mass hierarchies from strongly-coupled dynamics
Andreas Athenodorou (Department of Physics, University of Cyprus, B.O. Box 20537, 1678, Nicosia, Cyprus); Ed Bennett (Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP, U.K., Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Furo, Chikusa, Nagoya, 464-8602, Japan); Georg Bergner (Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012, Bern, Switzerland); Daniel Elander (National Institute for Theoretical Physics, School of Physics and Mandelstam Institute for Theoretical Physics, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg, Wits, 2050, South Africa); C.J. Lin (Institute of Physics, National Chiao-Tung University, 1001 Ta-Hsueh Road, Hsinchu, 30010, Taiwan, CNRS, Aix Marseille Université, Université de Toulon, Centre de Physique Théorique, UMR 7332, F-13288, Marseille, France); et al - Show all 7 authors
Besides the Higgs particle discovered in 2012, with mass 125 GeV, recent LHC data show tentative signals for new resonances in diboson as well as diphoton searches at high center-of-mass energies (2 TeV and 750 GeV, respectively). If these signals are confirmed (or other new resonances are discovered at the TeV scale), the large hierarchies between masses of new bosons require a dynamical explanation. Motivated by these tentative signals of new physics, we investigate the theoretical possibility that large hierarchies in the masses of glueballs could arise dynamically in new strongly-coupled gauge theories extending the standard model of particle physics. We study lattice data on non-Abelian gauge theories in the (near-)conformal regime as well as a simple toy model in the context of gauge/gravity dualities. We focus our attention on the ratio R between the mass of the lightest spin-2 and spin-0 resonances, that for technical reasons is a particularly convenient and clean observable to study. For models in which (non-perturbative) large anomalous dimensions arise dynamically, we show indications that this mass ratio can be large, with R> 5. Moreover,our results suggest that R might be related to universal properties of the IR fixed point. Our findings provide an interesting step towards understanding large mass ratios in the non-perturbative regime of quantum field theories with (near) IR conformal behaviour.
