Gonzàlez-Solís, SergiRastrojo Morote, Joel2025-09-182025-09-182025-06https://hdl.handle.net/2445/223245Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2025, Tutor: Sergi Gonzàlez-Solís de la FuenteIn this work, we determine the degree of mixing of the η and η′ mesons from the exclusive semileptonic D+ (s) → η(′)ℓ+νℓ and B+ → η(′)ℓ+νℓ decays. A controlled parametrization of the participating hadronic form factor, D(s) → η(′) and B → η(′), in combination with experimental measurements, has allowed us to determine ϕ = 40.6(4.8)◦ and ϕ = 42.3(3.7)◦ from the analyses of differential decay width distributions and ratios of branching ratios, respectively. Our results are in good agreement with a recent determination from the Lattice QCD Extended Twisted Mass Collaboration, ϕ = 39.3(2.0)◦, and larger than the naive estimate we calculate from Chiral Perturbation Theory at leading order ϕ = 33.5◦.7 p.application/pdfengcc-by-nc-nd (c) Rastrojo, 2025http://creativecommons.org/licenses/by-nc-nd/3.0/es/Factors de forma hadrònicsDesintegracions semi-leptòniquesTreballs de fi de grauHadronic form factorsSemileptonic decaysBachelor's thesesinfo:eu-repo/semantics/bachelorThesisinfo:eu-repo/semantics/openAccess