Abstract
In light of the discovery of a Higgs-like particle at the LHC, we revisit the status of the precision electroweak data, focusing on two discrepant observables: 1) the long-standing 2.4σ deviation in the forward-backward asymmetry of the bottom quark \( A_{\mathrm{FB}}^b \), and 2) the 2.3σ deviation in R b , the ratio of the \( Z\ \to\ b\overline{b} \) partial width to the inclusive hadronic width, which is now in tension after a recent calculation including new two-loop electroweak corrections. We consider possible resolutions of these discrepancies. Taking the data at face value, the most compelling scenario is that new physics directly affects \( A_{\mathrm{FB}}^b \) and R b , bringing the prediction into accord with the measured values. We propose a modified ‘Beautiful Mirrors’ scenario which contains new vector-like quarks that mix with the b quark, modifying the \( Zb\overline{b} \) vertex and thus correcting \( A_{\mathrm{FB}}^b \) and R b . We show that this scenario can lead to modifications to the production rates of the Higgs boson in certain channels, and in particular a sizable enhancement in the diphoton channel. We also describe additional collider tests of this scenario.
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Batell, B., Gori, S. & Wang, LT. Higgs couplings and precision electroweak data. J. High Energ. Phys. 2013, 139 (2013). https://doi.org/10.1007/JHEP01(2013)139
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DOI: https://doi.org/10.1007/JHEP01(2013)139