Title: Making dark matter out of light: Freeze-in from plasma effects

Abstract

Dark matter (DM) could couple to particles in the Standard Model (SM) through a light vector mediator. In the limit of small coupling, this portal could be responsible for producing the observed DM abundance through a mechanism known as freeze-in. Furthermore, the requisite DM-SM couplings provide a concrete benchmark for direct and indirect searches for DM. We present updated calculations of the relic abundance for DM produced by freeze-in through a light vector mediator. We identify an additional production channel: the decay of photons that acquire an in-medium plasma mass. These plasmon decays are a dominant channel for DM production for sub-MeV DM masses, and including this channel leads to a significant reduction in the predicted signal strength for DM searches. Accounting for production from both plasmon decays and annihilations of SM fermions, the DM acquires a highly nonthermal phase-space distribution which impacts the cosmology at later times; these cosmological effects will be explored in a companion paper.

Authors:

Dvorkin, Cora; Lin, Tongyan; Schutz, Katelin

Publication Date:

2019-06-11

Research Org.:

Univ. of California, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science Foundation (NSF); Hertz Foundation

OSTI Identifier:

1525559

Alternate Identifier(s):

OSTI ID: 1593893

Grant/Contract Number:  

[SC0019195; SC0019018; PHY-1748958; AST-1813694]

Resource Type:

Published Article

Journal Name:

Physical Review D

Additional Journal Information:

[Journal Name: Physical Review D Journal Volume: 99 Journal Issue: 11]; Journal ID: ISSN 2470-0010

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS