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Top-philic Z forces at the LHC

A preprint version of the article is available at arXiv.


Despite extensive searches for an additional neutral massive gauge boson at the LHC, a Z at the weak scale could still be present if its couplings to the first two generations of quarks are suppressed, in which case the production in hadron colliders relies on tree-level processes in association with heavy flavors or one-loop processes in association with a jet. We consider the low-energy effective theory of a top-philic Z and present possible UV completions. We clarify theoretical subtleties in evaluating the production of a top-philic Z at the LHC and examine carefully the treatment of ananomalous Z current in the low-energy effective theory. Recipes for properly computing the production rate in the Z + j channel are given. We discuss constraints from colliders and low-energy probes of new physics. As an application, we apply these considerations to models that use a weak-scale Z to explain possible violations of lepton universality in B meson decays, and show that the future running of a high luminosity LHC can potentially cover much of the remaining parameter space favored by this particular interpretation of the B physics anomaly.


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Fox, P.J., Low, I. & Zhang, Y. Top-philic Z forces at the LHC. J. High Energ. Phys. 2018, 74 (2018).

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  • Anomalies in Field and String Theories
  • Beyond Standard Model