Unified explanation of the anomalies in semileptonic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi></mml:math> decays and the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi></mml:math> mass
Marcel Algueró, Joaquim Matias, Andreas Crivellin, C. A. Manzari
Abstract
The discrepancies between the measurements of rare (semi)leptonic $B$ decays and the corresponding Standard Model predictions point convincingly toward the existence of new physics for which a heavy neutral gauge boson (${Z}^{\ensuremath{'}}$) is a prime candidate. However, the effect of the mixing of the ${Z}^{\ensuremath{'}}$ with the SM $Z$, even though it cannot be avoided by any symmetry, is usually assumed to be small and thus neglected in phenomenological analyses. In this paper we point out that a mixing of the naturally expected size leads to lepton flavor universal contributions, providing a very good fit to $B$ data. Furthermore, the global electroweak fit is affected by $Z\ensuremath{-}{Z}^{\ensuremath{'}}$ mixing where the tension in the $W$ mass, recently confirmed and strengthened by the CDF measurement, prefers a nonzero value of it. We find that a ${Z}^{\ensuremath{'}}$ boson with a mass between $\ensuremath{\approx}1--5\text{ }\text{ }\mathrm{TeV}$ can provide a unified explanations of the $B$ anomalies and the $W$ mass. This strongly suggest that the breaking of the new gauge symmetry giving raise to the ${Z}^{\ensuremath{'}}$ boson is linked to electroweak symmetry breaking with intriguing consequences for model building.