Muon g \u2212 2 anomaly and neutrino magnetic moments

K. S. Babu,Vishnu P. K.,Sudip Jana,Manfred Lindner

doi:10.1007/jhep10(2021)240

Abstract

We show that a unified framework based on an SU(2)H horizontal symmetry which generates a naturally large neutrino transition magnetic moment and explains the XENON1T electron recoil excess also predicts a positive shift in the muon anomalous magnetic moment. This shift is of the right magnitude to be consistent with the Brookhaven measurement as well as the recent Fermilab measurement of the muon g − 2. A relatively light neutral scalar from a Higgs doublet with mass near 100 GeV contributes to muon g − 2, while its charged partner induces the neutrino magnetic moment. In contrast to other multi-scalar theories, in the model presented here there is no freedom to control the sign and strength of the muon g − 2 contribution. We analyze the collider tests of this framework and find that the HL-LHC can probe the entire parameter space of these models.

Highlights

There has been considerable interest in understanding the long-standing discrepancy between the measured and predicted values of the anomalous magnetic moment of the muon, aμ
We show that a unified framework based on an SU(2)H horizontal symmetry which generates a naturally large neutrino transition magnetic moment and explains the XENON1T electron recoil excess predicts a positive shift in the muon anomalous magnetic moment
We focus on a specific class of models based on an SU(2)H horizontal symmetry acting on the electron and muon families that naturally leads to a large neutrino magnetic moment [6, 7]

Summary

Introduction

There has been considerable interest in understanding the long-standing discrepancy between the measured and predicted values of the anomalous magnetic moment of the muon, aμ. The neutrino magnetic moment needed to explain this excess lies in the range of (1.6−2.4) × 10−11μB, where μB stands for the electron Bohr magneton [5] Such a value would require new physics to exist around the TeV scale. We find that within this class of models, an explanation of the XENON1T excess will necessarily lead to a positive contribution to ∆aμ, which lies neatly within the Brookhaven and the recent Fermilab measurements of aμ [3]. This class of models is in accordance with Occam’s razor, explaining both anomalies in terms of the same new physics

Objectives

Findings

Conclusion