Abstract
We propose novel collider searches which can significantly improve the LHC reach to new gauge bosons Z′ with mixed anomalies with the electroweak (EW) gauge group. Such a Z′ necessarily acquires a Chern-Simons coupling to the EW gauge bosons and these couplings can drive both exotic Z decays into Z′γ if the new gauge boson is sufficiently light, as well as Z′ decays into EW gauge bosons. While the exotic decay rate of the heavy Z into Z′γ is too small to be observed at the LHC, for a light Z′, we show the potential of a lepton jet search in association with a photon to probe the rare decay Z → Z′γ.
Highlights
3 GeV Z' 10 GeV Z' 30 GeV Z'1/ d /d R 1/ d /d RR in figure 2.4 The shoulder in the background ∆R γ distribution is due to Zγ production, whose kinematics are more similar to our signal process than radiative Z decay
Such a Z necessarily acquires a Chern-Simons coupling to the EW gauge bosons and these couplings can drive both exotic Z decays into Z γ if the new gauge boson is sufficiently light, as well as Z decays into EW gauge bosons
While the exotic decay rate of the heavy Z into Z γ is too small to be observed at the LHC, for a light Z, we show the potential of a lepton jet search in association with a photon to probe the rare decay Z → Z γ
Summary
Consider a U(1) symmetry that has a mixed anomaly with the EW group SU(2) × U(1). Clearly this theory cannot be extended up to arbitrary high scales [15]. Unlike (2.5) this expression is suppressed by the lighter Z mass This behaviour occurs because the effects of the integrated out spectators are suppressed by the cutoff of the theory, which is proportional to the Z mass (2.1) due to the spectators being chiral under U(1). This renders the exotic width of the heavy Z into Zγ practically unobservable and we do not pursue this direction any further
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