The Effect of Quark Sector Minimal Flavor Violation on Neutrinoless Double Beta Decay

TL;DR

This paper investigates how minimal flavor violation in the quark sector constrains new physics operators affecting neutrinoless double beta decay, linking flavor symmetries to observable lepton number violation.

Contribution

It introduces phenomenological constraints on higher dimension operators under minimal flavor violation, significantly limiting their impact on neutrinoless double beta decay.

Findings

Most operators cannot contribute at observable rates due to constraints.

Operators that can mimic Majorana neutrino masses have cutoffs below 1 TeV.

Constraints imply potential for direct detection at LHC or future colliders.

Abstract

The question of whether neutrino masses are Dirac or Majorana is one of the most important, and most difficult, questions remaining in the neutrino sector. Searches for neutrinoless double beta-decay may help to resolve this question, but are also sensitive to new, higher dimension Delta L=2 operators. In this paper we place two phenomenological constraints on these operators at dimension d<=11. First, we require that the operators obey the quark flavor symmetries of the Standard Model, with any violation of the symmetries being due to Yukawa interactions, a scheme known as Minimal Flavor Violation (MFV). Second, we require that the operators which generate neutrinoless double beta-decay, and any operators related by the flavor symmetries, do not induce neutrino masses above 0.05 eV, the limit implied by the atmospheric neutrino data. We find that these requirements severely constrain the operators which can violate lepton number, such that most can no longer contribute to neutrinoless double beta-decay at observable rates. It is noteworthy that quark flavor symmetries can play such a strong role in constraining new leptonic physics, even when that physics is not quark flavor changing. Those few operators that can mimic a Majorana neutrino mass then appear with cutoffs below a TeV, and represent new physics which could be directly probed at the LHC or a future linear collider.