Eur. Phys. J. C (2022) 82: 42
https://doi.org/10.1140/epjc/s10052-021-09957-1

Regular Article - Theoretical Physics

B-anomalies from flavorful U(1)${}^{\prime }$ extensions, safely

¹ Fakultät Physik, TU Dortmund, Otto-Hahn-Str.4, 44221, Dortmund, Germany
² Department of Physics and Astronomy, University of Sussex, BN1 9QH, Brighton, UK

^e tom2.steudtner@tu-dortmund.de

Received: 22 September 2021
Accepted: 17 December 2021
Published online: 15 January 2022

Abstract

$U{(1)}^{\prime }$ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare B-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the $U{(1)}^{\prime }$ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with $B_s$-mixing constraints, with hints for electron-muon universality violation, and the global $b\to s$ fit. We further investigate the complete two-loop running of gauge, Yukawa and quartic couplings up to the Planck scale to constrain low-energy parameters and enhance the predictive power. A characteristic of models is that the $Z^{\prime }$ with TeV-ish mass predominantly decays to invisibles, i.e. new fermions or neutrinos. $Z^{\prime }$-production can be studied at a future muon collider. While benchmarks feature predominantly left-handed couplings $C_9^{\mu }$ and $C_{10}^{\mu }$, right-handed ones can be accommodated as well.