Symmetric Mass Generation

We consider a field theoretical model where a SU(2) fermion doublet, subjected to non-Abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an irrelevant Wilson-like term. Despite the presence of these two chiral breaking operators in the Lagrangian, an exact symmetry acting on fermions and scalars prevents perturbative mass corrections. In the phase where fermions are massless (Wigner phase) the Yukawa coupling can be tuned to a criti...

Origin of mass may be strong dynamics of matter in the vacuum. Since the initial proposal of Nambu for the origin of the nucleon mass, the dynamical symmetry breaking in the strongly coupled underlying theories has been expanding the horizons in the context of the modern version of the origin of mass beyond the Standard Model (SM). The Nambu-Jona-Lasinio (NJL) model is a typical strong coupling theory with the non-zero critical coupling, in sharp contrast to its precedent mod...

It is known that, under short-range interactions many topological superconductors (TSC) and topological insulators (TI) are trivialized, which means the boundary state of the system can be trivially gapped out by interaction without leading to symmetry breaking or topological ground state degeneracy. This phenomenon is also referred to as "symmetric mass generation" (SMG), and has attracted broad attentions from both the condensed matter and high energy physics communities. H...

Symmetric mass generation is a novel mechanism to give gapless fermions a mass gap by non-perturbative interactions without generating any fermion bilinear condensation. The previous studies of symmetric mass generation have been limited to Dirac/Weyl/Majorana fermions with zero Fermi volume in the free fermion limit. In this work, we generalize the concept of symmetric mass generation to Fermi liquid with a finite Fermi volume and discuss how to gap out the Fermi surfaces by...

This talk is in two parts both entitled mass production requires precision engineering. The first is about the dynamical generation of mass for matter particles in gauge theories. I will explain how the details of this depend on a precision knowledge of the interactions. The second is about tests of the mechanism of chiral symmetry breaking in QCD that the precision engineering of high luminosity colliders and particle detectors will shortly make possible. Since the latter ...

Recent developments on approaches to the quark lepton mass problem are reviewed. In particular we discuss dynamical calculations of the top quark mass at (a) the infrared quasifixed point of the Minimal Supersymmetric Standard Model renormalisation group equations, and (b) a strongly first order critical point of the Standard Model effective potential. The phenomenology of symmetric mass matrix ans\"{a}tze with texture zeros at the unification scale is also considered. The un...

Based on a recent proposal according to which elementary particle masses could be generated by a non-perturbative dynamical phenomenon, alternative to the Higgs mechanism, we carry out lattice simulations of a model where a non-abelian strongly interacting fermion doublet is also coupled to a doublet of complex scalar fields via a Yukawa and an "irrelevant" Wilson-like term. In this pioneering study we use naive fermions and work in the quenched approximation. We present prel...

We study the generation of fermion mass in a context where interactions break a discrete chiral symmetry. Then, fermion mass is not protected by a symmetry, no symmetry is broken by the generation of mass, and a vanishing mass no longer enhances a symmetry. We elaborate these scenarios for template fermionic and Yukawa theories in three dimensions where mass can be generated either by fluctuations, strong dynamics, or the vacuum expectation value of a scalar field. We find th...

We construct a four dimensional lattice gauge theory in which fermions acquire mass without breaking symmetries as a result of gauge interactions. Our model consists of reduced staggered fermions transforming in the bifundamental representation of a $SU(2)\times SU(2)$ gauge symmetry. This fermion representation ensures that single site bilinear mass terms vanish identically. A symmetric four fermion operator is however allowed and we show numerical results that show that a c...

We call attention to the fact that the gauge symmetry $SU(3)\times SU(2)_{_L}\times U(1)$ of the Standard Model can be easily and naturally extended by the local conformal symmetry connected with the possibility of choosing the local length scale. Restricting the admissible interactions to the lowest order conformal invariant interactions one gets the unique form of total lagrangian. It contains all Standard Model fields and gravitational interaction. Using the unitary and th...