Abstract
The advent of the Gaia era has led to potentially revolutionary understanding of dark matter (DM) dynamics in our galaxy, which has important consequences for direct detection (DD) experiments. In this paper, we study how the empirical DM velocity distribution inferred from Gaia-Sausage, a dominant substructure in the solar neighborhood, affects the interpretation of DD data. We survey different classes of operators in the non-relativistic effective field theory that could arise from several relativistic benchmark models and emphasize that the Gaia velocity distribution could modify both the total number of events as well as the shape of the differential recoil spectra, the two primary observables in DD experiments. Employing the euclideanized signal method, we investigate the effects of the Gaia distribution on reconstructing DM model parameters and identifying the correct DM model given a positive signal at future DD experiments. We find that for light DM with mass ~10 GeV, the Gaia distribution poses an additional challenge for characterizing DM interactions with ordinary matter, which may be addressed by combining complementary DD experiments with different targets and lowering the detection threshold. Meanwhile, for heavy DM with mass above ~30 GeV, depending on the type of DM model, there could be a (moderate) improvement in the sensitivity at future DD experiments.
Highlights
Confirming the existence of dark matter (DM) through a variety of cosmological and astrophysical observations has been one of the major successes of 20th century physics
Our approach is quite different from both traditional forecasting approaches for DM direct detection that used benchmark-dependent mock data sets [36,37,38,39,40], or analyses which studied the effect of uncertainties in standard halo model (SHM) on constraining the DM particle physics properties [41,42,43,44]
We combine the formulas and methodology presented in previous sections for studying how DM velocity distribution inferred from Gaia sausage could affect reconstruction of various DM particle physics parameters at next-generation direct detection (DD) experiments
Summary
Confirming the existence of dark matter (DM) through a variety of cosmological and astrophysical observations has been one of the major successes of 20th century physics. We find that both the DM mass and the recoil energy dependence of the model could enhance or suppress the effect of the Gaia velocity distribution vis-á-vis the SHM while inferring the DM model parameters Our approach is quite different from both traditional forecasting approaches for DM direct detection that used benchmark-dependent mock data sets [36,37,38,39,40], or analyses which studied the effect of uncertainties in SHM on constraining the DM particle physics properties [41,42,43,44].
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