White dwarf axions, PAMELA data, and flipped-SU(5)

TL;DR

This paper proposes a supersymmetric flipped-SU(5) model explaining white dwarf axion hints and PAMELA positron excess through a light axion and specific dark matter components, predicting observable signals at the LHC.

Contribution

It introduces a novel flipped-SU(5) framework with additional symmetries that simultaneously addresses astrophysical anomalies and dark matter, with testable collider predictions.

Findings

Light electrophilic axion of 0.5 meV mass explains white dwarf cooling.

Model accounts for high-energy positron excess without anti-proton excess.

Potential detection of charged SU(2) singlet E at the LHC.

Abstract

Recently, there are two hints arising from physics beyond the standard model. One is a possible energy loss mechanism due to emission of very weakly interacting light particles from white dwarf stars, with a coupling strength ~ 0.7x10^{-13}, and another is the high energy positrons observed by the PAMELA satellite experiment. We construct a supersymmetric flipped-SU(5) model, SU(5)xU(1)_X with appropriate additional symmetries, [U(1)_H]_{gauge}x[U(1)_RxU(1)_\Gamma]_{global}xZ_2, such that these are explained by a very light electrophilic axion of mass 0.5 meV from the spontaneously broken U(1)_\Gamma and two component cold dark matters from Z_2 parity. We show that in the flipped-SU(5) there exists a basic mechanism for allowing excess positrons through the charged SU(2) singlet leptons, but not allowing anti-proton excess due to the absence of the SU(2) singlet quarks. We show the discovery potential of the charged SU(2) singlet E at the LHC experiments by observing the electron and positron spectrum. With these symmetries, we also comment on the mass hierarchy between the top and bottom quarks.