arXiv subjects

Mario W. Barela

Publications and source records attributed to Mario W. Barela.

8 recordsLinked to original sources

arXiv2024

Phenomenology of the doubly-charged vector bilepton

The Standard Model stands as the first established, complete (gravity aside), fundamental theory of nature. In the other hand, it is unable to account for some universal observations -- besides possessing a number of undesirable characteristics. Thus, there is a pressing need for new physics, which, in the high energy realm, usually imply new particles. In this thesis, we delve into one such particle: the doubly-charged vector bilepton. This particle is a singular feature of Beyond the Standard Model theories and its phenomenology is still incipient. We focus, in particular, on its power as a mediator of Charged Lepton Flavour Mediation, a type of process which, in turn, may represent a smoking gun with respect to its discovery or constraining of its parameters. Such processes have not been skeptically explored, and the lepton mixing in their interaction with the $U^{\pm \pm}$ not been properly focused on. The first step we take is investigating what bounds an LHC trimuon process may impose on the parameter space of this particle. The results motivate us to look for alternative experimental sources of limits. The seven 3-body lepton decay channels delivered a great prospect, and we perform a detailed, model independent analysis of what they can imply for the $U^{\pm \pm}$ and other two exotic species. Special attention is paid to occurring interferences between new contributions. Finally, we proceed to construct a thorough analysis of the evolution of couplings in the Minimal 3-3-1 Model, the main theory incorporating a vector bilepton, examining how it is threatened by Landau poles in its abelian coupling. We explicitly obtain the 1-loop contributions of exotic particles to the runnings, finding that the perturbative regime of the model is in fact considerably larger than conventionally assumed.

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arXiv2024

Effects of new physics on the Standard Model parameters and vice versa

This note discusses the matter of probing Beyond the Standard Model physics and how, to succeed in this quest, the interpretations of the Standard Model regarding observed phenomena must be utilized with caution. We give several specific examples of why this is necessary and assess general scenarios in which it is specially important. In particular, we call attention to the fact that once the Standard Model (SM) is finally replaced, the parameters of the new theory which embed those of the SM must be rederived directly from data instead of inherited through their expected relations with those of the SM.

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arXiv2024

On the 3-3-1 Landau pole

The Minimal 3-3-1 Model (m331) offers a compelling extension of the Standard Model, with a rich particle content that allows for exciting phenomenological possibilities. The parameter space of the theory, however, remains relatively unconstrained. Regarding its effective range of validity, it is understood in the literature that the $U(1)_X$ coupling diverges at around $\SI{4}{TeV}$, which threatens the character of the theory as fundamental. In this work, we rederive the running of the electroweak gauge couplings through a more precise, effective approach, in which the complete parametrization of the full 3-3-1 symmetry is considered at all energies. We show that this more rigorous description guarantees a larger perturbative range for the m331, with a most conservative upper limit going up to around $\SI{8.5}{TeV}$. We also reconsider the usefulness of a relation which eliminates a free parameter of the model in favour of known quantities, regularly invoked within the m331 context.

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arXiv2024

Di-Higgs Signatures in Neutral Naturalness

The Higgs boson was the last fundamental piece of the Standard Model to be experimentally confirmed. LHC is embarked in a quest to probe the possibility that this particle provides a portal to new physics. One front of this quest consists in measuring the interactions of the Higgs with itself and with other SM particles to a high precision. In a more exotic front, the LHC is searching for the possibility that a pair of Higgses (HH) is the evidence of a new resonance. Such resonances are predicted in models with extended Higgs sectors, extra dimensions, and in models with exotic bound states. In this paper we show how scalar quirks in Folded Supersymmetry can give rise to HH resonances. We point out a viable sector of the parameter space in which HH is the dominant decay channel for these {\it squirkonium} bound states. We found that future runs of the LHC could discover HH resonances in the range of 0.5 - 1.6 TeV under reasonable assumptions. Furthermore, for a given mass and width of the HH signal, the model predicts the branching ratio of the subsequent decay modes of the heavy resonance. Finding the extra decay modes in the predicted pattern can serve as a smoking gun to confirm the model.

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arXiv2022

Constraints on exotic particle masses from flavor violating charged lepton decays and the role of interference

Together with any Beyond the Standard Model ultraviolet complete, renormalizable model, one or several exotic particles are usually hypothesized. $C\!P$-even neutral and doubly-charged scalars are common, well known examples which can contribute to the seven 3-body Charged Lepton Flavor Violating decays. The experimental bounds on each Branching Ratio within this set of processes provide a good test for new physics that can induce powerful constraints on relevant parameter spaces. This is specially true for a third species of particle which, unlike the previous two, is a rare feature of renormalizable models: a doubly charged vector bilepton. We show how these purely leptonic bounds can indeed induce relevant exclusion regions for the corresponding particles masses, stronger than what have been considered in the literature for the alternative flavor conserving case, and examine how interference effects can influence these regions in a non-trivial way.

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arXiv2021

An exact lower bound within a 331 model closing solution

On this note we show how one specific proposal of solution to the problem of `closing' the well motivated 331 model to the Standard Model actually implies a lower bound for the otherwise theoretically free vacuum expectation value $v_χ$.

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arXiv2021

Can scalars matter? A vector bilepton phenomenologic example

Expecting scalar contributions to be less important to a given observable signal than vector ones, in usual scenarios, is a natural intuition. Such assertion should hold for a great part of physically relevant parameter space within most models of interest. In this work, besides stressing that the proposition is not general, we show how the alternative possibility may give light to interesting phenomena.

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arXiv2020

Trimuon production at the LHC

No process without a standard model (SM) background has been observed so far. As a tool in the study of a class of models containing doubly charged vector bileptons, we propose one such process that, violating lepton flavor number conservation, has no contribution from the SM: $pp\to μ^+μ^+μ^- e^-$. By carefully isolating the parameters to keep them free, we are able to acquire a notion of how a possible PMNS-like matrix present in the relevant charged current parametrization could affect the observables. We find that an interesting section of the space of parameters can be explored at the current LHC in the specified conditions.

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