Diphoton excess from hidden U(1) gauge symmetry with large kinetic mixing

TL;DR

This paper proposes a model explaining the 750 GeV diphoton excess via a hidden U(1) gauge symmetry with large kinetic mixing, unification at high energy, and distinctive collider signatures.

Contribution

It introduces a novel hidden U(1) gauge symmetry with large kinetic mixing that explains the diphoton excess and predicts unique collider signals and unification without rapid proton decay.

Findings

Unification of gauge couplings around 10^{17} GeV.

Predicted collider signatures include photon plus missing energy events.

Model accommodates various collider and cosmological constraints.

Abstract

We show that the 750 GeV diphoton excess can be explained by introducing vector-like quarks and hidden fermions charged under a hidden U(1) gauge symmetry, which has a relatively large coupling constant as well as a significant kinetic mixing with U(1)$_Y$. With the large kinetic mixing, the standard model gauge couplings unify around $10^{17}$ GeV, suggesting the grand unified theory without too rapid proton decay. Our scenario predicts events with a photon and missing transverse momentum, and its cross section is related to that for the diphoton excess through the kinetic mixing. We also discuss other possible collider signatures and cosmology, including various ways to evade constraints on exotic stable charged particles. In some cases where the 750 GeV diphoton excess is due to diaxion decays, our scenario also predicts triphoton and tetraphoton signals.