Study of the impact of unitarity bounds on analysis of Vector Boson Scattering with same-sign $W$ processes at LHC.

Effective Field Theories (EFT) are a powerful instrument for researching the effects of Beyond Standard Model (BSM) physics. The introduction of EFT contributions could lead to an unphysical growth of scattering amplitudes and then to a violation of unitarity above a particular value of the center-of-mass energy. To validate the EFT approach in this region is necessary to implement unitarity constraints. The object of this communication is a study of Vector Boson Scattering processes with same-sign $W$ bosons in the context of SM EFT. The analysis is performed at the generator level on Monte Carlo samples at a luminosity of 138 inverse fb, corresponding to the data collected during Run II of the LHC. The kinematic constraints necessary to restore the physical sense of the approach in high-energy regions are determined as a function of Wilson coefficients of relevant dimension-six and dimension-eight operators, and the impact of the unitarity constraints on the observables is quantified via a likelihood-based approach. Finally, the consequences of the obtained results are discussed.