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Résumé |
Composite Higgs models remain an appealing possibility to avoid the presence of a light fundamental scalar boson in
the EWSB sector. In these models, the Brout-Englert-Higgs boson is a composite Nambu-Goldstone boson, arising
from the spontaneous breaking, towards a subgroup H, of a global symmetry group G of a hyper-colour gauge theory
that confines at the multi-TeV scale. The EW symmetry group is contained in H, and is thus preserved. EWSB arises
through vacuum misalignment, triggered by explicit symmetry-breaking effects, thus allowing to decouple the EW
breaking scale from the dynamical scale of the hyper-colour interactions.
The seminar is devoted to an in-depth study of a model based on a Sp(2N) hyper-colour gauge group, consisting of two sectors.
The EW sector, described by four Weyl fermions in the (pseudo-real) fundamental representation of
the Sp(2N) gauge group, is based on the SU(4)/Sp(4) symmetry-breaking pattern. In order to eventually endow the
SM fermions with masses via partial compositeness, a second sector, with six Weyl fermions in the (real) anti-symmetric
representation of Sp(2N), is introduced. The corresponding symmetry-breaking pattern corresponds to the SU(6)/SO(6)
coset. The mass spectrum of this theory and the couplings of the various mesonic states to the currents of the
global SU(4)xSU(6) symmetry group are computed within an approximate dynamical framework based on a generalization
of the NJL description of the QCD gauge dynamics. The non-trivial features arising from the interplay between the two sectors,
linked through an effective operator which incorporates the effects of the gauge anomalies of the axial singlet
currents, are analyzed in detail. |
