Fractional-charge hadrons and leptons to tell the Standard Model group apart

TL;DR

This paper explores how fractional electric charges of hadrons and leptons can distinguish between different possible gauge groups of the Standard Model, which share the same Lie algebra but differ in their global structure.

Contribution

It proposes using fractional charge spectra as a novel method to differentiate the gauge group structure of the Standard Model.

Findings

Fractional charges depend on the global structure of the gauge group.

Different gauge groups allow for distinct fractional charge values.

Fractional charge measurements could identify the true gauge group.

Abstract

The gauge group of strong and electroweak interactions in Nature could be any of the four that share the same Lie algebra, $SU(3)_c\times SU(2)_L\times U(1)_Y/Z_p\equiv G_p$ with $Z_p=\left\{Z_6,Z_3,Z_2,Z_1\right\}$. Each of these cases allows in its spectrum for the matter fields of the SM but also for new distinctive representations, e.g. under the assumption that $q_L$ possesses the minimum possible hypercharge in Nature, $G_p$ allows for particles with a multiple of $p\,e/6$ for electric charge. This letter discusses how these new possibilities in the spectrum could be used to tell the SM group apart.