Cosmological Constraint on the Light Gravitino Mass from CMB Lensing and Cosmic Shear

TL;DR

This paper constrains the mass of light gravitinos using cosmological observations, showing that their mass must be less than 4.7 eV, which tightens previous limits and impacts theories of early universe physics.

Contribution

It provides the first combined cosmological constraint on light gravitino mass using CMB lensing, cosmic shear, and galaxy clustering data.

Findings

Gravitino mass constrained to less than 4.7 eV (95% C.L.)

Tighter than previous Ly-$\\alpha$ forest clustering constraints

Implications for baryogenesis scenarios involving light gravitinos

Abstract

Light gravitinos of mass $\lesssim \mathcal{O} (10)$ eV are of particular interest in cosmology, offering various baryogenesis scenarios without suffering from the cosmological gravitino problem. The gravitino may contribute considerably to the total matter content of the Universe and affect structure formation from early to present epochs. After the gravitinos decouple from other particles in the early Universe, they free-stream and consequently suppress density fluctuations of (sub-)galactic length scales. Observations of structure at the relevant length-scales can be used to infer or constrain the mass and the abundance of light gravitinos. We derive constraints on the light gravitino mass using the data of cosmic microwave background (CMB) lensing from Planck and of cosmic shear from the Canada France Hawaii Lensing Survey, combined with analyses of the primary CMB anisotropies and the signature of baryon acoustic oscillations in galaxy distributions. The obtained constraint on the gravitino mass is $m_{3/2} < 4.7$ eV (95% C.L.), which is substantially tighter than the previous constraint from clustering analysis of Ly-$\alpha$ forests.