Z′and CDEX Related Dark Matter Theory

As the existence of dark matter is more widely confirmed, investigating the natureof dark matter has become central issue and frontier of fundamental physics. In the21stcentury, with the accurate measurement of cosmology and direct and indirect detectionresults, dark matter has become the main motivation for the research of new physicsbeyond the standard model after the discovery of Higgs.The current research focuses on the hot topic issue of dark matter. With the previ-ous research on the extended U(1)′electroweak chiral efective Lagrangian and CDEXdirect detection experiments, in this research we discussed Z′dark matter theory, inelas-tic scattering of isospin violation dark matter and electron recoil from dark matter areinvestigated from theoretical and experimental aspects.For the theoretical aspects of dark matter, we found that the extension of standardmodel with the extended electroweak chiral efective Lagrangian can be the candidatetheory of dark matter after some assumptions are made. We investigated the constraintsof the coupling constant of this model from relic density, direct detection and indirectdetection, and found the coupling is constrained to a region of103102with Z′darkmatter of mass mZ′>100GeV. We also pointed out that the model cannot contribution asignificant isospin violation interaction, which can reconcile the conflict between resultsfrom diferent direct detect experiments, and the coupling constant within this limitedregion cannot give observable signals at LHC.For the experimental aspects of dark matter, especially with the first dark matterdirect detection experiment in China, we try to introduce isospin violation and inelasticscattering mechanisms in dark matter model to ameliorate the tensions between resultsof diferent direct detection experiments. We found that only using isospin violation orinelastic scattering mechanism can not fully reconcile the conflict between CDMS-Siresult and null results from superCDMS. But when taking into account of both mecha-nisms, we can make the results from diferent experiments compatible, except for Co-GeNT result. To get these models, a new vector gauge boson to connect the standardmodel particle and dark matter is also needed. Because CDEX experiment cannot distin-guish nuclear recoil and electron recoil, we calculate the energy spectrum of scatteringbetween dark matter and electrons. We found that with the free electron assumes, the scattering between dark matter and electron is not negligible at an energy region closeto the current threshold (0.3keVee), While in the assumes that the electrons are in boundstates, the spectrum of scattering between dark matter and He electrons is significantlysuppressed relative to the case with free electron assumption. Collaborative researchwith nuclear and atomic and molecular department is required when considering calcu-lations with more complicated atoms or crystals.