The impact of operator interference and target complementarity in dark matter direct detection experiments

We present a method to determine the limits on the DM-nucleon interaction strengths for one experiment in the non-relativistic effective theory by taking the interference of operators into account. Further, we extend the method to combine several experiments. To apply the developed methods, we use data from the XENON1T and PICO60 collaborations. The relaxation caused by the interference among operators can be up to four orders of magnitude. The strengthening of the limits by combining the analysis of both experiments can be up to four orders of magnitude.