Heavy Vectors: Bounds and Hopes

Tuesday, 6 October 2015 at 11:15 in Y36 J33

Electroweak-charged massive spin one resonances are common predictions of a wide set of new physics scenarios, among which all the constructions, motivated by Naturalness, where a new strongly-interacting composite sector is the ultimate responsible (most likely through a composite Nambu—Goldstone Higgs) of the breaking of the Electroweak symmetry. Focusing for definiteness on resonances in the triplet of the Electroweak group, I will show how the phenomenology of this kind of particles can be characterised in terms of a simple and general phenomenological Lagrangian that is suited to describe heavy vectors of radically different physical origin. This characterisation provides the starting point for a comprehensive LHC search program. The relative importance of the different experimental search channels, and the LHC run-1 constraints, crucially depend on the physical origin of the heavy vector, namely on whether it emerges as an “elementary” gauge field of a renormalizable theory or as a “composite” object. The case of a composite vector turns out to be rather poorly explored by the run-1 data and a significant improvement is expected at run-2. To conclude, I will show that a vector triplet of this sort, definitely of composite nature, might account for the ATLAS excess in the hadronic di-boson final state without being excluded by other searches and possibly accounting for less significant excesses observed in other channels.