DESI forecast for Dark Matter-Neutrino interactions using EFTofLSS

TL;DR

The paper tests the applicability of the Effective Field Theory of Large Scale Structure (EFTofLSS) to dark matter models with suppressed small-scale power, focusing on dark matter–neutrino (IDM) interactions. Using a DESI ELG-like survey, it forecasts constraints from the redshift-space galaxy power spectrum, validating EFTofLSS against N-body IDM simulations and exploring how priors on EFT nuisance parameters affect sensitivity to the IDM coupling $u_{ u\chi}$. In optimistic scenarios with fixed redshift evolution of EFT parameters, DESI could tightly bound $u_{ u\chi}$ and even reveal IDM signals, but conservative priors yield degeneracies that erode sensitivity, underscoring the need for physically motivated priors from simulations. The work highlights both the potential and the current limitations of EFTofLSS for probing nonstandard DM, pointing to future improvements via higher-order statistics and better understanding of EFT counterterms and stochastic terms across redshift.

Abstract

We apply the Effective Field Theory of Large Scale Structure (EFTofLSS) to non-standard models of dark matter with suppressed small-scale structure imprinted by early-time physics, here exemplified by interacting dark matter (IDM) coupled to standard model neutrinos, and cross-check that the EFTofLSS has no trouble replicating the real-space halo-halo power spectrum from N-body simulations. We perform forecasts for a DESI ELG-like experiment using the redshift-space power spectrum and find that, under very conservative priors on these parameters, the EFTofLSS is not expected to yield strong constraints on dark matter interactions. However, with a better understanding of the evolution of counterterms and stochastic terms with redshift, realistic IDM models could in principle be detected using the full-shape power spectrum analysis of such a spectroscopic galaxy survey.

Figures (7)

• Figure 1: Linear and EFTofLSS matter power spectrum at redshift $z=0$ for two IDM scenarios, with 50% and 90% IDM, respectively, as well as standard CDM for reference. For the nonlinear power spectrum we have set counterterms to zero. It is evident that the scenario with the larger IDM fraction is more suppressed, but for both models the suppression starts at the same scale, as they have the same interaction strength $u_{\nu\chi}$.
• Figure 2: Triangle plot of the one-dimensional posteriors and two-dimensional (68% and 95%) iso-credibility contours of the MCMC chains using a CDM-only fiducial and constant counterterms, with fiducial values marked with black lines. It is evident that the fiducial parameter values are well recovered using both the CDM-only (as in fiducial) and 90% IDM models, indicating that such an experiment can yield robust limits on the DM-neutrino interaction strength.
• Figure 3: Triangle plot of the ne-dimensional posteriors and two-dimensional (68% and 95%) iso-credibility contours of our MCMC chains using a 90% IDM fiducial, with fiducial values marked with black lines, including only those parameters with significant difference between the 90% IDM and CDM chains. It is evident that the fiducial parameter values are well recovered with the 90% IDM models, while there are $\sim 1\sigma$ shifts in central values recovered in the CDM only chains.
• Figure 4: Triangle plot of the 2d posteriors of the optimistic (green), intermediate (blue), and pessimistic (red) analyses with a CDM fiducial cosmology. It is clear that stronger priors on stochastic and counterterms greatly improve the constraining power for $u_{\nu\chi}$ in particular.
• Figure 5: Triangle plot of the 2d posteriors of the optimistic (green), intermediate (blue), and pessimistic (red) analyses with a 90% IDM fiducial cosmology. Again, it is clear that stronger priors on stochastic and counterterms greatly improve the constraining power for $u_{\nu\chi}$ in particular.