LHC 750 GeV diphoton excess and muon $(g-2)$

TL;DR

This paper explores how a 750 GeV diphoton excess at the LHC could relate to the muon g-2 anomaly, analyzing scalar or pseudoscalar particles' contributions within extended Higgs models.

Contribution

It investigates the potential link between the LHC diphoton excess and muon g-2, highlighting the role of scalar representations and their Yukawa couplings in explaining the anomaly.

Findings

Scalar singlet contribution to muon g-2 is small.

Doublet scalars can explain muon g-2 with enhanced Yukawa couplings.

Implications for extended Higgs sectors are discussed.

Abstract

We consider implications of the diphoton excess recently observed at the LHC on the anomalous magnetic dipole moment of the muon $(g-2)_\mu = 2 a_\mu$, hypothesizing that the possible 750 GeV resonance is a (pseudo)scalar particle. The (pseudo)scalar-$\gamma$-$\gamma$ interaction implied by the diphoton events might generically contribute to $a_\mu$ via 2-loop Barr-Zee type diagrams in a broad class of models. If the scalar is an $SU(2)_L$ singlet, the new contribution to $a_\mu$ is much smaller than the current anomaly, $\Delta a_\mu \equiv a_\mu^{\rm exp}-a_\mu^{\rm SM} \approx (30 \pm 10) \times 10^{-10}$, since the scalar can complete the Barr-Zee diagrams only through its mixing with the Standard Model Higgs boson. If the (pseudo)scalar belongs to an $SU(2)_L$ doublet in an extended Higgs sector, then by contrast, $\Delta a_\mu$ can be easily accommodated with the aid of an enhanced Yukawa coupling of the (pseudo)scalar to the muon such as in the Type-II or -X two Higgs doublet model.