Searches for New Physics in the Standard Model's Electroweak Sector: Quartic Anomalous Couplings with Vector Boson Fusion and Flavor Changed Neutral Current in the $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ model

In this thesis we investigated, at partonic level and leading order, the LHC potencial operating with $\sqrt{s}=14$ TeV and integrated luminosity of $L=100\;{fb}^{-1}$ to probe "pure" (without triple vertex contributions) anomalous electroweak quartic couplings, $WWWW$ and $WWZZ$, in the semileptonic $pp \rightarrow l^{\pm}ν_{l}jjjj$ channel, enhanced by the Vector Boson Fusion collider signatures. Deviations on SM quartic couplings were parameterized in a model independent approach, realized linearly ($L_{S0}$ and $L_{S1}$ operators) or not ($L_{4}$ and $L_{5}$ operators), on the basis of effective lagrangians. Being our analysis essentially events counting-and-cut based, we took into account all possible backgrounds (irreducible, QCD and top quarks processes) considered at ${\cal O}(α_{em}^{6})$, ${\cal O(α_{em}^{4}α_{s}^{2})$ and ${\cal O}(α_{em}^{2}α_{s}^{4})$. In this way, we have obtained the following constraints for the non-linear $α_{4}$ and $α_{5}$ anomalous couplings: $|α_{4,5}| \lesssim 0.01$ to 0.02 at 3$σ$. Based on non-linear results, we have estimated, for a specific choice of factorization and renormalization scale, the linear parameters $f_{0}$ and $f_{1}$ constraints as $-22 \leq \dfrac{f_{0}}{Λ^{4}}\;({TeV}^{-4}) \leq 20, \quad {and} \quad -26 \leq \dfrac{f_{1}}{Λ^{4}}\;({TeV}^{-4}) \leq 24$ at 3$σ$. On a different approach, manipulating one extension of the SM named $331_{RHN}$, we have evaluated the contribution of new sources of FCNC for the difference of mass of neutral meson systems, $K_{0}-\bar{K_{0}}$, $D^{0}-\bar{D^0}$ and $B^0_d-\bar{B^0_d}$. Bounds related to these systems may be significantly strengthened in the presence of these new interactions allowing stronger constraints on the parameter space of the model.

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