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

Exponential suppression or commonly known as the Boltzmann suppression in thenumber density of dark matter is the key ingredient for creating chemicalimbalance prior to the usual thermal freeze-out. A degenerate/quasi-degeneratedark sector can experience a different exponential suppression in the numberdensity analogous to the radioactive decay law leading to a delayed freeze-outmechanism of dark matter known as the co-decaying dark matter. In this work, westudy the dynamics of a multicomponent dark matter from thermally decoupleddegenerate dark sector in a hidden U$(1)_{X}$ extension of the Standard Model.We compute the relic density of dark matter frozen-out through the co-decayingmechanism by solving four coupled Boltzmann equations. We demonstrate howtemperature $T^\prime $ of the dark sector changes due to all types of$3\rightarrow 2$ and $2\rightarrow 2$ interactions along with the eternalexpansion of the Universe. We find that $3\rightarrow 2$ interactions enhance$T^\prime$ by producing energetic particles in the dark sector while the excessheat is transferred by $2\rightarrow 2$ interactions to the entire dark sector.As the direct detection is possible only through the feeble portal couplings,we investigate the neutrino and $\gamma$-ray signals from dark matterannihilation via one step cascade processes and compare our results with themeasured fluxes of atmospheric neutrinos by Super-Kamiokande and diffuse$\gamma$-rays by Fermi-LAT, EGRET, INTEGRAL collaborations. We find that thepresent scenario easily evades all the existing bounds from atmosphericneutrino and diffuse $\gamma$-ray observations for degenerate dark sector.However, the constraints are significant for quasi degenerate scenario.

When Freeze-out occurs due to a non-Boltzmann suppression: A study of degenerate dark sector