DAMA/LIBRA-phase2 in WIMP effective models

TL;DR

This paper analyzes DAMA/LIBRA-phase2 data using a comprehensive effective WIMP interaction framework, revealing better fits for various couplings and velocity-dependent models, but all are in tension with other experimental constraints.

Contribution

It introduces a systematic analysis of DAMA data within the most general effective WIMP interaction models, extending beyond standard spin-independent interactions.

Findings

Most effective couplings improve fit over standard models.

Velocity-dependent cross sections better fit high WIMP mass data.

All solutions conflict with XENON1T and PICO60 exclusion limits.

Abstract

The DAMA/LIBRA collaboration has recently released updated results from their search for the annual modulation signal expected from Dark Matter (DM) scattering in their NaI detectors. We have fitted the updated DAMA result for the modulation amplitudes in terms of a Weakly Interacting Massive Particle (WIMP) signal, parameterizing the interaction with nuclei in terms of the most general effective Lagrangian for a WIMP particle spin up to 1/2, systematically assuming dominance of one of the 14 possible interaction terms, and assuming for the WIMP velocity distribution a standard Maxwellian. We find that most of the couplings of the non-relativistic effective Hamiltonian can provide a better fit compared to the standard Spin Independent interaction case, and with a reduced fine-tuning of the three parameters (WIMP mass, WIMP-nucleon effective cross-section and ratio between the WIMP-neutron and the WIMP-proton couplings). Moreover, effective models for which the cross section depends explicitly on the WIMP incoming velocity can provide a better fit of the DAMA data at large values of $m_{\chi}$ compared to the standard velocity-independent cross-section due to a different phase of the modulation amplitudes. All the best fit solutions are in tension with exclusion plots of both XENON1T and PICO60.