Gauge-singlet dark matter in a left-right symmetric model with   spontaneous CP violation
  We propose a dark matter (DM) scenario in an extension of a left-right symmetric model with a gauge-singlet scalar field. The gauge-singlet scalar can automatically become a DM candidate, provided that both P and CP symmetries are only broken spontaneously. Thus no extra discrete symmetries are needed to make the DM candidate stable. After constraining the model parameters from the observed relic DM density we make predictions for direct detection experiments. We show that for some parameter range, the predicted WIMP-nucleon elastic scattering cross section can reach the current experimental upper bound, which can be tested by the experiments in the near future. 
Wan-Lei Guo, Li-Ming Wang, Yue-Liang Wu, Yu-Feng Zhou and Ci Zhuang