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

TL;DR

This paper investigates the potential of the LHC at 14 TeV to detect anomalous electroweak quartic couplings and flavor-changing neutral currents within specific models, providing constraints on new physics parameters through event analysis.

Contribution

It presents a model-independent analysis of anomalous quartic couplings at the LHC and explores flavor-changing neutral currents in a specific extended model, deriving new bounds on these phenomena.

Findings

Constraints on non-linear anomalous couplings: |_{4,5}| \u2264 0.01-0.02 at 3c

Linear parameters f_0 and f_1 constrained within _0/^4 and _1/^4 ranges at 3c

Bounds on FCNC effects in meson systems can be significantly strengthened in the extended model.

Abstract

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 $pp \rightarrow l^{\pm}\nu_{l}jjjj$ 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 ${\cal O}(\alpha_{em}^{6})$, ${\cal O(\alpha_{em}^{4}\alpha_{s}^{2})$ and ${\cal O}(\alpha_{em}^{2}\alpha_{s}^{4})$. In this way, we have obtained the following constraints for the non-linear $\alpha_{4}$ and $\alpha_{5}$ anomalous couplings: $|\alpha_{4,5}| \lesssim 0.01$ to 0.02 at 3$\sigma$. 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 $-22 \leq \dfrac{f_{0}}{\Lambda^{4}}\;({TeV}^{-4}) \leq 20, \quad {and} \quad -26 \leq \dfrac{f_{1}}{\Lambda^{4}}\;({TeV}^{-4}) \leq 24$ at 3$\sigma$. 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.