Shining LUX on isospin-violating dark matter beyond leading order

Abstract

Editor: W. HaxtonIsospin-violating dark matter (IVDM) has been proposed as a viable scenario to reconcile conflicting positive and null results from direct detection dark matter experiments. We show that the lowest-order dark matter-nucleus scattering rate can receive large and nucleus-dependent corrections at next-toleading order (NLO) in the chiral expansion. The size of these corrections depends on the specific couplings of dark matter to quark flavors and gluons. In general the full NLO dark-matter-nucleus cross-section is not adequately described by just the zero-energy proton and neutron couplings. These statements are concretely illustrated in a scenario where the dark matter couples to quarks through scalar operators. We find the canonical IVDM scenario can reconcile the null XENON and LUX results and the recent CDMS-Si findings provided its couplings to second and third generation quarks either lie on a special line or are suppressed. Equally good fits with new values of the neutron-to-proton coupling ratio are found in the presence of nonzero heavy quark couplings. We also derive the structure of the scattering amplitude to all orders in the chiral expansion and show the best fit points at NLO are robust against higher order corrections provided the chiral expansion is itself well-behaved. CDMS-Si remains in tension with LUX and XENON10/100 but is not excluded.

Direct detection of dark matter polarizability

“…In [10,11,13], the relevance of 2-body densities in DM detection has been pointed out, although as a subleading effect in the chiral counting. In this paper we find another interesting application for DM direct detection, where the two-body term plays a dominant role.…”

“…For the experimental details of the analysis we refer the reader to [13] and references therein. The color coding is Xenon100 (red), LUX (green), CDMS-Ge (blue).…”

Isospin-violating dark matter with colored mediators

“…As LUX experiment [11] currently imposes the most stringent bound on DM, one necessarily considers DM that has negligible interaction with the Xenon nucleus. Recent studies after the LUX result [17][18][19]27] have shown that the isospin-violating DM is still compatible with one of positive signals, those of the CDMS-II Si experiment.…”

Hadronic uncertainties and isospin violation in supersymmetric dark matter models

“…Given the huge parameter space, it is necessary to make additional, simplifying assumptions 2 Although see [23] for important higher-order corrections to σ 0 which can reduce the value of y, albeit with large uncertainties. 3 Corrections to the single-nucleon picture underlying (2.1) in the form of two-nucleon currents can be systematically taken into account using effective field theory [29][30][31][32].…”