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

We investigate the phenomenology of the dark $Z$ boson, $Z_d$, which isassociated with a new Abelian gauge symmetry and couples to the standard modelparticles via kinetic mixing $\varepsilon$ and mass mixing $\varepsilon_Z^{}$.We examine two cases: (i) $Z_d$ is lighter than the $Z$ boson, and (ii) $Z_d$is heavier than that. In the first case, it is known that $Z_d$ causes adeviation in the weak mixing angle at low energies from the standard modelprediction. We study the prediction in the model and compare it with the latestexperimental data. In the second case, the $Z$-$Z_d$ mixing enhances the $W$boson mass. We investigate the effect of $Z_d$ on various electroweakobservables including the $W$ boson mass using the $S$, $T$, and $U$parameters. We point out an interesting feature: in the limit $\varepsilon \to0$, the equation $S = - U$ holds independently of the mass of $Z_d$ and thesize of $\varepsilon_Z^{}$, while $|S|\gg |U|$ in many new physics models. Wefind that the dark $Z$ boson with a mass of $O(100)~\mathrm{GeV}$ with arelatively large mass mixing can reproduce the CDF result within $2\sigma$while avoiding all other experimental constraints. Such dark $Z$ bosons areexpected to be tested at future high-energy colliders.

Searching for new physics effects in future $W$ mass and $\sin^2\theta_W (Q^2)$ determinations