Combined explanation of the&lt;em&gt; Z&lt;/em&gt; →&lt;em&gt; bb¯&lt;/em&gt; forward-backward asymmetry, the Cabibbo angle anomaly, and &lt;em&gt;τ&lt;/em&gt; → &lt;em&gt;μνν&lt;/em&gt; and b → &lt;em&gt;sℓ&lt;sup&gt;+&lt;/sup&gt;ℓ&lt;sup&gt;-&lt;/sup&gt;&lt;/em&gt; Data

Crivellin, Andreas; Manzari, Claudio Andrea; Algueró, Marcel; Matias, Joaquim

doi:10.1103/PhysRevLett.127.011801

Combined explanation of the Z → bb¯ forward-backward asymmetry, the Cabibbo angle anomaly, and τ → μνν and b → sℓ⁺ℓ^- Data

Crivellin A, Manzari CA, Algueró M & Matias J

Citation

Crivellin, A., Manzari, C. A., Algueró, M., & Matias, J. (2021). Combined explanation of the Z → bb¯ forward-backward asymmetry, the Cabibbo angle anomaly, and τ → μνν and b → sℓ⁺ℓ^- Data. Physical Review Letters, 127(1), 011801 (8 pp.). https://doi.org/10.1103/PhysRevLett.127.011801

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:38949

In this Letter, we propose a simple model that can provide a combined explanation of the Z → bb¯ forward-backward asymmetry, the Cabibbo angle anomaly (CAA), τ → μνν and b → sℓ⁺ℓ^- data. This model is obtained by extending the standard model (SM) by two heavy vectorlike quarks (an SU(2)_L doublet (singlet) with hypercharge -5/6 (-1/3), two new scalars (a neutral and a singly charged one), and a gauged L_μ - L_τ symmetry. The mixing of the new quarks with the SM ones, after electroweak symmetry breaking, does not only explain Z → bb¯ data, but also generates a lepton flavor universal contribution to b → sℓ⁺ℓ^- transitions. Together with the lepton flavor universality violating effect, generated by loop-induced Z′ penguins involving the charged scalar and the heavy quarks, it gives an excellent fit to data (6.1σ better than the SM). Furthermore, the charged scalar (neutral vector) gives a necessarily constructive tree-level (loop) effect in μ → eνν (τ → μνν), which can naturally account for the CAA (Br[τ → μνν]/Br[τ → eνν] and Br[τ → μνν]/Br[μ → eνν]).