Little Higgs Dark Matter after PandaX-II/LUX 2016 and LHC Run-1

TL;DR

This paper examines the constraints on the mass of $A_H$ dark matter in the Littlest Higgs model with $T$ parity, using data from collider experiments, dark matter relic abundance, and direct detection, finding significant lower bounds.

Contribution

It provides the first comprehensive analysis combining collider, relic abundance, and direct detection data to constrain $A_H$ dark matter mass in the LHT model.

Findings

Higgs data and electroweak precision observables exclude $A_H$ masses up to 99 GeV.

LUX and PandaX-II data exclude $A_H$ masses below 270-380 GeV depending on co-annihilation partners.

LHC monojet results set a lower limit of 540 GeV on $A_H$ mass for certain co-annihilation scenarios.

Abstract

In the Littlest Higgs model with $T$ parity (LHT), the $T$-odd heavy photon ($A_H$) is weakly interacting and can play the role of dark matter. We investigate the lower limit on the mass of $A_H$ dark matter under the constraints from Higgs data, EWPOs, $R_b$, Planck 2015 dark matter relic abundance, PandaX-II/LUX 2016 direct detections and LHC-8 TeV monojet results. We find that (1) Higgs data, EWPOs and $R_b$ can exclude the mass of $A_H$ up to 99 GeV. To produce the correct dark matter relic abundance, $A_H$ has to co-annihilate with $T$-odd quarks ($q_H$) or leptons ($\ell_H$); (2) the LUX (PandaX-II) 2016 data can further exclude $m_{A_H}<380 (270)$ GeV for $\ell_H$-$A_H$ co-annihilation and $m_{A_H}<350 (240)$ GeV for $q_H-A_H$ co-annihilation; (3) LHC-8 TeV monojet result can give a strong lower limit, $m_{A_H}>540$ GeV, for $q_H$-$A_H$ co-annihilation; (4) future XENON1T (2017) experiment can fully cover the parameter space of $\ell_H$-$A_H$ co-annihilation and will push the lower limit of $m_{A_H}$ up to about 640 GeV for $q_H$-$A_H$ co-annihilation.