Abstract
We study a simple model in which the recently reported 750 GeV diphoton excess arises from a composite pseudo Nambu-Goldstone boson---hidden pion---produced by gluon fusion and decaying into two photons. The model only introduces an extra hidden gauge group at the TeV scale with a vectorlike quark in the bifundamental representation of the hidden and standard model gauge groups. We calculate the masses of all the hidden pions and analyze their experimental signatures and constraints. We find that two colored hidden pions must be near the current experimental limits, and hence are probed in the near future. We study physics of would-be stable particles---the composite states that do not decay purely by the hidden and standard model gauge dynamics---in detail, including constraints from cosmology. We discuss possible theoretical structures above the TeV scale, e.g. conformal dynamics and supersymmetry, and their phenomenological implications. We also discuss an extension of the minimal model in which there is an extra hidden quark that is singlet under the standard model and has a mass smaller than the hidden dynamical scale. This provides two standard model singlet hidden pions that can both be viewed as diphoton/diboson resonances produced by gluon fusion. We discuss several scenarios in which these (and other) resonances can be used to explain various excesses seen in the LHC data.
Highlights
Simple mnemonic; it does not mean that the three factors of GSM are unified at the TeV scale
We study a simple model in which the recently reported 750 GeV diphoton excess arises from a composite pseudo Nambu-Goldstone boson — hidden pion — produced by gluon fusion and decaying into two photons
We discuss an extension of the minimal model in which there is an extra hidden quark that is singlet under the standard model and has a mass smaller than the hidden dynamical scale
Summary
Where we take mD,L > 0, which does not lead to a loss of generality if we keep all the phases in the other part of the theory. These masses are assumed to be sufficiently smaller than the dynamical scale, mD,L Λ, so that ΨD,L and Ψ D,L can be regarded as light quarks from the point of view of the GH dynamics. The model preserves gauge coupling unification at the level of the standard model; this is significant especially given the possible threshold corrections around the TeV and unification scales (see, e.g., [22]). The unification of the couplings becomes even better if we introduce supersymmetry near the TeV scale (see section 3)
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