Seminars IFIC

Unitarized EFT for a strongly interacting BSM Electroweak Sector

by Rafael Delgado López (Universidad Complutense)

Monday, 19 June 2017 from to (Europe/Brussels)
at Universe ( 1001-Primera-1-1-1 - Paterna. Seminario )
I use the nonlinear electroweak chiral Lagrangian (EChL) and the mathematical properties of the S-matrix (encoded into unitarization methods) for sampling the collider phenomenology of a (hypothetical) strongly interacting electroweak symmetry breaking sector (EWSBS). The EChL Lagrangian is used as an intermediate energy approximation (E~500 GeV), where the Equivalence Theorem is valid but the EFT does not violate unitarity. EChL is used by the LHC experimentalists as a useful parameterization of slight deviations from the SM, as exposed in the last CERN Yellow Report of the LHC Higgs Cross Section Working Group.

Of highest interest is the EWSBS and the description of the scattering processes between longitudinally polarized gauge bosons and the Higgs-like particle discovered at the LHC. Hence, the A[W_L,Z_L,h-->W_L,Z_L,h] scattering amplitudes are computed at NLO. Unitarization procedures are used to extend the validity range of the EFT up to the first resonance, where the EFT perturbative expansion breaks down. Several unitarization procedures are tested, and their validity regions checked.

As an extension of this work, we couple a (hypothetical) strongly interacting EWSBS with t\bar t and gamma-gamma states, since they are more easily accessible for the LHC. We assume a weakly interacting coupling to t\bar t and gamma-gamma, while keeping a strongly interacting EWSBS. For this project, we develop a modified version of several unitarization procedures. 
Organised by LHCPHENO