Abstract
We review numerical results for models with gauge group Sp(2N), discussing the glueball spectrum in the large-N limit, the quenched meson spectrum of Sp(4) with Dirac fermions in the fundamental and in the antisymmetric representation and the Sp(4) gauge model with two dynamical Dirac flavours. We also present preliminary results for the meson spectrum in the Sp(4) gauge theory with two fundamental and three antisymmetric Dirac flavours. The main motivation of our programme is to test whether this latter model is viable as a realisation of Higgs compositeness via the pseudo Nambu Goldstone mechanism and at the same time can provide partial top compositeness. In this respect, we report and briefly discuss preliminary results for the mass of the composite baryon made with two fundamental and one antisymmetric fermion (chimera baryon), whose physical properties are highly constrained if partial top compositeness is at work. Our investigation shows that a fully non-perturbative study of Higgs compositeness and partial top compositeness in Sp(4) is within reach with our current lattice methodology.
Highlights
Sp(4) gauge theory with two fundamental and three antisymmetric Dirac fermion flavours has been suggested as a possible template [1,2,3] for beyond the standard model strong interactions that can give rise to a composite Higgs boson through the breaking of the global fundamental flavour symmetry [4] and at the same time to a partial composite top quark state
Partial top compositeness results from the mixing of the standard model top quark with a chimera baryon, i.e. a baryonic state formed with two fermions in the fundamental and one fermion in the antisymmetric representation
Following the programme we started in [18], we have performed a set of extensive simulations aimed to assess the viability of Sp(4) gauge theory with two fundamental and three antisymmetric fermions as a realisation of the composite Higgs and of the partial top compositeness mechanism
Summary
Sp(4) gauge theory with two fundamental and three antisymmetric Dirac fermion flavours has been suggested as a possible template [1,2,3] for beyond the standard model strong interactions that can give rise to a composite Higgs boson through the breaking of the global fundamental flavour symmetry [4] and at the same time to a partial composite top quark state. Partial top compositeness results from the mixing of the standard model top quark with a chimera baryon, i.e. a baryonic state formed with two fermions in the fundamental and one fermion in the antisymmetric representation. We shall discuss our previous and current lattice investigations of the composite Higgs mechanism and of partial top compositeness using Sp(4) gauge theory as a concrete realisation (for studies involving SU(4), see, e.g., [6,7,8]), starting from special cases of the target action and approaching the latter in a crescendo of complexity.
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