arXiv subjects

Ulises J. Saldana-Salazar

Publications and source records attributed to Ulises J. Saldana-Salazar.

3 recordsLinked to original sources

arXiv2019

The mass ratios parametrization

The observed hierarchy in the fermion masses, which imply a set of small mass ratios, is not naturally small regarding 't Hooft's criteria. In this work, in a model independent approach, we introduce a set of conditions by which fermion mass ratios become natural. Interestingly, these conditions demand that fermion mixing should be described by the four independent mass ratios of each fermion sector. Application of this set of conditions to the standard theory enables one to understand the mains aspects in quark and lepton mixing. This feature can be taken as a strong evidence for the existence in Nature of a flavour symmetry. Also, for this analysis to work in the lepton sector, neutrino masses should have normal ordering with the lightest neutrino mass satisfying the lower bound, $m_{ν1} \geqslant (5.0\pm 0.1) \text{ meV}$, making the approach testable.

hep-ph↗

arXiv2018

Texture zeros and hierarchical masses from flavour (mis)alignment

We introduce an unconventional interpretation of the fermion mass matrix elements. As the full rotational freedom of the gauge-kinetic terms renders a set of infinite bases called weak bases, basis-dependent structures as mass matrices are unphysical. Matrix invariants, on the other hand, provide a set of basis-independent objects which are of more relevance. We employ one of these invariants to give a new parametrization of the mass matrices. By virtue of it, one gains control over its implicit implications on several mass matrix structures. The key element is the trace invariant which resembles the equation of a hypersphere with a radius equal to the Frobenius norm of the mass matrix. With the concepts of alignment or misalignment we can identify texture zeros with certain alignments whereas Froggatt-Nielsen structures in the matrix elements are governed by misalignment. This method allows further insights of traditional approaches to the underlying flavour geometry.

hep-ph↗

arXiv2017

Higgs couplings and new signals from Flavon-Higgs mixing effects within multi-scalar models

Testing the properties of the Higgs particle discovered at the LHC and searching for new physics signals, are some of the most important tasks of Particle Physics today. Current measurements of the Higgs couplings to fermions and gauge bosons, seem consistent with the Standard Model, and when taken as a function of the particle mass, should lay on a single line. However, in models with an extended Higgs sector the diagonal Higgs couplings to up-quarks, down-quarks and charged leptons, could lay on different lines, while non-diagonal flavor-violating Higgs couplings could appear too. We describe these possibilities within the context of multi-Higgs doublet models that employ the Froggatt-Nielsen (FN) mechanism to generate the Yukawa hierarchies. Furthermore, one of the doublets can be chosen to be of the inert type, which provides a viable dark matter candidate. The mixing of the Higgs doublets with the flavon field, can provide plenty of interesting signals, including: i) small corrections to the couplings of the SM-like Higgs, ii) exotic signals from the flavon fields, iii) new signatures from the heavy Higgs bosons. These aspects are studied within a specific model with 3+1 Higgs doublets and a singlet FN field. Constraints on the model are derived from the study of K and D mixing and the Higgs search at the LHC. For last, the implications from the latter aforementioned constraints to the FCNC top decay $t\to ch$ are presented too.

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