Abstract: Loss of unitarity in an effective field theory is often cured by the appearance of dynamical resonances, revealing the presence of new degrees of freedom. These resonances may manifest themselves when suitable unitarization techniques are implemented in the effective theory, which in the scalar-isoscalar channel require making use of the coupled-channel formalism. Conversely, experimental detection of a resonance may provide interesting information on the couplings and constants of the relevant effective theory. By applying a systematical procedure we shall try to confront the effective theory with the absence or presence of resonances at the LHC in the vector boson fusion channel, our main goal being the Higgs trilinear and quartic self-couplings, that in the coupled-channel formalism are accesible at leading order. This is especially interesting as the experimental measurement of the Higgs potential remains a challenging task. In the final part of this thesis, we apply the previously studied unitarization techniques to the case of the Einstein-Hilbert action describing gravitational interactions. Treating it as the leading term of an effective theory, the possible scalar resonances appearing in graviton-graviton scattering, that need to be described in the coupled-channel formalism, provide insight of higher-order corrections of the effective gravitational action. 

Tribunal:

President: Dr. Antonio Pich Zardoya

Secretary: Dr. Lluis Garrido Beltran

Vocal: Dr. María José Herrero Solans

Suplents:

Dr. Alexandre Pomarol

Dr. Carla Marin

Director: Drs. Domènec Espriu Climent and Federico Mescia

Tutor: Dr. Joan Soto Riera