English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Recently, there have been hints for dark matter (DM) annihilation in thegalactic center to one or more photon lines. In order to achieve the observedphoton line flux, DM must have a relatively large effective coupling tophotons, typically generated radiatively from large couplings to chargedparticles. When kinematically accessible, direct annihilation of DM to thesecharged particles is far too large to accommodate both the DM relic density andconstraints from the observed flux of continuum photons from the galacticcenter, halo and dwarf galaxies. We discuss three exceptions to theseobstacles, generating the observed line signal while providing the correctrelic density and evading photon continuum constraints. The exceptions are (i)coannihilation, where the DM density is set by interactions with a heavierstate that is not populated today, (ii) forbidden channels, where DMannihilates to heavier states that are kinematically blocked today, but open inthe early Universe, and (iii) asymmetric DM, where the relic density is set bya primordial asymmetry. We build simple models to realize these scenarios.

Three Exceptions for Thermal Dark Matter with Enhanced Annihilation to Gamma Gamma