Complete vectorlike fourth family with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">U</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mn>1</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>: A global analysis
Junichiro Kawamura, Stuart Raby, Andreas Trautner
Abstract
We present an in-depth analysis of a recently proposed Standard Model extension with a complete fourth generation of quarks and leptons, which are vectorlike with respect to the Standard Model gauge group and charged under a new spontaneously broken vectorlike $\mathrm{U}(1{)}^{\ensuremath{'}}$ gauge symmetry. The model is designed to explain the known muon anomalies, i.e., the observed deviations from Standard Model predictions in the anomalous magnetic moment of the muon, $\mathrm{\ensuremath{\Delta}}{a}_{\ensuremath{\mu}}$, and in $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ processes. We perform a global ${\ensuremath{\chi}}^{2}$ analysis of the data with 65 model parameters and including 98 observables. We find many points with ${\ensuremath{\chi}}^{2}$ per degree of freedom $\ensuremath{\le}1$. The vectorlike leptons and the new heavy ${Z}^{\ensuremath{'}}$ are typically much lighter than a TeV and would, thus, be eminently visible at the HL-LHC.