Phenomenology of the lhc and flavour factories
- Autores: Ana Peñuelas Martínez
- Directores de la Tesis: Antonio Pich (dir. tes.)
- Lectura: En la Universitat de València ( España ) en 2020
- Idioma: español
- Tribunal Calificador de la Tesis: Joaquim Matias Espona (presid.), Jorge Portolés Ibáñez (secret.), Svjetlana Fajfer (voc.)
- Programa de doctorado: Programa de Doctorado en Física por la Universitat de València (Estudi General)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
The forces and particle content of nature are described by the Standard Model (SM) of particle physics. This model was developed in the later half of the 20th century thanks to the progress at the theoretical aspects and the confirmation of the predicted particles at experiments and colliders. The discovery of the Higgs boson in 2012 represented a crucial confirmation of the model and initiated an age of exploration at the Large Hadron Collider (LHC). Even though the success of the SM was confirmed, some theoretical and experimental issues seem to indicate that this cannot be the ultimate theory. In this thesis, some of the paths indicating deviations from the SM will be followed.
After a general overview of the SM in Chapter 1, a set of simple extensions of the scalar sector of the SM will be presented in Chapter 2, namely the N-Higgs doublet models (NHDMs), containing N Higgs doublets with the same quantum numbers as the SM one. These models present non-diagonal Yukawa couplings, which cannot be accommodated experimentally and therefore need to be suppressed. The most general way for suppress- ing such non-diagonal interactions is tree-level alignment in flavour space, described in Chapter 2. Flavour alignment is broken at loop level, due to quantum corrections. This is studied in Chapter 6, where we show that models are phenomenologically safe after including these corrections. Then, in Chapter 7 a global fit of a CP-conserving NHDM with N = 2 doublets will be performed, including several theoretical, electroweak, flavour and Higgs observables. The fit will be performed with the code HEPfit, presented in Chapter 5.
The second path that will be explored are the charged B-anomalies. These anoma- lies are deviations with respect to the SM predictions in b → c transitions, with the ones appearing in the ratios RD and RD∗ being the most interesting. After a general overview of the transitions and relevant observables in Chapter 4, two different effective field theory (EFT) fits will be performed in Chapter 8. In the first one, the most general Hamiltonian containing dimensions-six operators is considered, working with a minimal set of assumptions: new physics is only present in the third generation of leptons, the CP-conserving limit is taken, there are no light right-handed neutrinos and electroweak symmetry breaking is linearly realized. Later, the last two assumptions are relaxed, and fits are extended to include operators appearing from non-linear symmetry breaking and operators describing right-handed neutrinos. The EFT approach, followed in the fits, is described in Chapter 3.
Finally, the electroweak top and bottom quark couplings will be studied in Chapter 9. In this chapter, we will present a global fit to the relevant effective electroweak dimension- six operators, performed using HEPfit. Bounds will be discussed for these operators using LEP/SLC and LHC data. In addition, prospects on future colliders such as the high-luminosity phase of the LHC and ILC have been set. The top-quark Yukawa coupling will be studied in detail, which leads to a percent-level determination.
