Gravitational Imprints of Flavor Hierarchies.

Admir Greljo,Ben A Stefanek,Toby Opferkuch

doi:10.1103/physrevlett.124.171802

Abstract

The mass hierarchy among the three generations of quarks and charged leptons is one of the greatest mysteries in particle physics. In various flavor models, the origin of this phenomenon is attributed to a series of hierarchical spontaneous symmetry breakings, most of which are beyond the reach of particle colliders. We point out that the observation of a multipeaked stochastic gravitational wave signal from a series of cosmological phase transitions could well be a unique probe of the mechanism behind flavor hierarchies. To illustrate this point, we show how near future ground- and space-based gravitational wave observatories could detect up to three peaks in the recently proposed PS^{3} model.

Highlights

Introduction.—The first direct detection of gravitational waves (GW) [1] was a stunning confirmation of the theory of general relativity and marked the discovery of the only messenger via which the universe can be probed back to the Planck era
Many particle physics processes that produce a stochastic gravitational wave background have already been identified, such as the primordial spectrum expected from inflation [10,11,12], violent first order phase transitions (FOPTs) [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38], cosmic strings [39,40,41,42], nonperturbative particle production [43,44,45,46,47,48,49], primordial black holes [50,51,52], etc
A longstanding question within fundamental physics is that of the flavor puzzle, which refers to why the standard model (SM) fermion Yukawa couplings are spread over so many orders of magnitude, with a top quark Yukawa that is Oð1Þ but an electron Yukawa which is five orders of magnitude smaller

Summary

Introduction

Introduction.—The first direct detection of gravitational waves (GW) [1] was a stunning confirmation of the theory of general relativity and marked the discovery of the only messenger via which the universe can be probed back to the Planck era. We point out that the observation of a multipeaked stochastic gravitational wave signal from a series of cosmological phase transitions could well be a unique probe of the mechanism behind flavor hierarchies. Transition is set by the vacuum expectation value (VEV) in the broken phase, the observation of a multipeaked signal could contain information about the scales of multiple spontaneous symmetry breakings (SSBs), with the first breaking giving the highest frequency peak and the last the lowest.

Results

Conclusion