Little Higgs dark matter after PandaX-II/LUX-2016 and LHC Run-1

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 ( ℓ _H ); (2) the LUX (PandaX-II) 2016 data can further exclude {m}_{A_H} < 380(270) GeV for ℓ _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 ℓ _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.