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 ($\ell_H$); (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.
