LHC 750 GeV diphoton excess and muon (g − 2)

We consider implications of the diphoton excess recently observed at the LHC on the anomalous magnetic dipole moment of the muon (g−2)μ=2aμ(g−2)μ=2aμ, hypothesizing that the possible 750 GeV resonance is a (pseudo)scalar particle ϕ(∼). The ϕ(∼)-γ-γ   interaction implied by the diphoton events might generically contribute to aμaμ via 2-loop Barr-Zee type diagrams in a broad class of models. If ϕ(∼) is an SU(2)LSU(2)L singlet, the new contribution to aμaμ is much smaller than the current anomaly, Δaμ≡aμexp−aμSM≈(30±10)×10−10, since the scalar can complete the Barr-Zee diagrams only through its mixing with the Standard Model Higgs boson. If ϕ(∼) belongs to an SU(2)LSU(2)L doublet in an extended Higgs sector, then by contrast, ΔaμΔaμ can be easily accommodated with the aid of an enhanced Yukawa coupling of ϕ(∼) to the muon such as in the Type-II or -X two Higgs doublet model.