Banca de DEFESA: DIEGO DOMINGUES LOPES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : DIEGO DOMINGUES LOPES
DATA : 03/05/2021
HORA: 14:00
LOCAL: Por participação remota.
TÍTULO:

Models and Phenomenological Studies of Áxions and Áxion Particles at the LHC

PÁGINAS: 140
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física das Partículas Elementares e Campos
ESPECIALIDADE: Teorias Específicas e Modelos de Interação; Sistemática de Partículas; Raios Cósmicos
RESUMO:

In this thesis we study models and phenomenology of axions and axion-like particles (ALPs). Particularly, we discuss a Standard Model extension based on the $SU(3)_C\otimes SU(3)_L\otimes U(1)_X$ gauge symmetry that relates the mass hierarchy of the fermions with the strong CP problem solution through the $U(1)_{PQ}$ Peccei-Quinn symmetry. This last symmetry arises accidentally with the imposition of a discrete $\ZZ_9$ symmetry, which also secludes the different scales in the double seesaw mechanism taking place in the neutrino sector. The symmetry breakdown is performed by three scalar triplets plus a scalar singlet hosting an axion field, whose particle excitation can be a component of dark matter. Combining the different energy scales, we obtain a natural hierarchy to the fermions. The model may be tested by looking for the possible production of the new particles at the LHC.

Following, we present prospects to probe the ALP couplings to sterile neutrinos. We found that mono-photon searches have the potential to constrain ALP couplings to sterile neutrinos when a new heavy scalar boosts the ALP decay yields. Working within an effective field theory approach, we scan the parameters space to establish the reach of the 13 TeV LHC to probe such couplings. We also present an UV-complete model for ALPs and sterile neutrinos whose parameters are spanned by our EFT approach. We found regions of the parameters space evading several experimental constraints that can be probed at the LHC, including a region yet not excluded in the $m_a \times g_{a \gamma \gamma}$ diagram.

Finally we study the Higgs-ALP interaction at the LHC, searching for a resonance at the Higgs pole given by the $h \to aa \to \gamma \gamma + jj$ process. This final state allows us to constrain the parameters in the effective Lagrangian considered, and it is promising in regions where the search for ALP decays only in photons is not effective, specially for ALP masses between 0.4 and 10 GeV.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1544374 - ALEX GOMES DIAS
Membro Titular - Examinador(a) Interno ao Programa - 1676343 - PEDRO GALLI MERCADANTE
Membro Titular - Examinador(a) Externo ao Programa - 2211564 - ANDRE PANIAGO LESSA
Membro Titular - Examinador(a) Externo à Instituição - PAULO SÉRGIO RODRIGUES DA SILVA
Membro Titular - Examinador(a) Externo à Instituição - MARCO ANDRÉ FERREIRA DIAS - UNIFESP
Membro Suplente - Examinador(a) Interno ao Programa - 1770888 - CELIO ADREGA DE MOURA JUNIOR
Membro Suplente - Examinador(a) Externo ao Programa - 3057567 - CHEE SHENG FONG
Membro Suplente - Examinador(a) Externo à Instituição - BRUCE LEHMANN SANCHEZ VEGA - UFMG
Membro Suplente - Examinador(a) Externo à Instituição - YARA DO AMARAL COUTINHO - UFRJ