Generation flow in field theory and strings

Abstract

Nontrivial strong dynamics often leads to the appearance of chiral composites. In phenomenological applications, these can either play the role of Standard Model particles or lift chiral exotics by partnering with them in mass terms. As a consequence, the RG flow may change the effective number of chiral generations, a phenomenon we call generation flow. We provide explicit constructions of globally consistent string models exhibiting generation flow. Since such constructions were misclassified in the traditional model searches, our results imply that more care than usually appreciated has to be taken when scanning string compactifications for realistic models.

Generation flow in field theory and strings

“…Furthermore, we discuss the stability of the chirally symmetric vacua in sconfining models under the deformations which induce generation flow. While such deformations may generally destabilize the vacua by non-perturbative dynamics (see [8] for a more detailed discussion), we argue that the chirally symmetric vacua survive in our models. In Section 4, we collect evidence for the existence of string models exhibiting generation flow by presenting explicit examples.…”

“…We begin by briefly reviewing dynamics of supersymmetric gapped fermion models introduced in [6]. In the following we will take the approach of [8] to building models of chiral gapped fermions. This approach starts with SUSY QCD models that exhibit confinement without chiral symmetry breaking on smooth moduli space [1].…”

“…Indeed, while lifting SU(2) s D-flat directions, the deformation (3) introduces new classical flat directions, those parameterized by SU(2) s singlets S. Since any VEVs for S would break the chiral symmetry, it is important to verify that the non-perturbative dynamical superpotential (2) does not destabilize these directions. A careful analysis [8] of the full superpotential in ( 2) and ( 3) demonstrates that SU(2) s dynamics generates an effective superpotential for gauge singlets S stabilizing them at the origin. 7 While referring the reader to [8] for the full analysis, we present a simple argument here.…”

“…A careful analysis [8] of the full superpotential in ( 2) and ( 3) demonstrates that SU(2) s dynamics generates an effective superpotential for gauge singlets S stabilizing them at the origin. 7 While referring the reader to [8] for the full analysis, we present a simple argument here. Consider the theory at large S where all quark superfields become heavy.…”

“…Generalizations to s-confining Sp(2N) with SU(2N + 4) global symmetry are straightforward [6]. 8 However, for phenomenological purposes one is interested in similar models with SU(5) or SU(3) × SU(2) × U(1) global symmetry which can then be identified with the GUT or the SM gauge group. As shown in [6], this can be easily achieved simply by considering the model of Section 2.2 and identifying GUT or SM gauge group with an appropriate subgroup of SU (6).…”