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Lucia Stockdale

Publications and source records attributed to Lucia Stockdale.

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Classification of minimal models producing b, c and tau masses at one-loop level

The Standard Model neither provides a dynamical explanation for the quark and lepton mass hierarchies, nor a rationale for why all of these masses save that of the top quark are suppressed compared to the electroweak scale. Motivated by this, we explore the alternative radiative mass generation hypothesis, specialising to the generation of the bottom, charm, and tau masses at one-loop level. A classification of all minimal models that use exotic scalars and exotic fermions only is presented, resulting in 25 possibilities featuring four exotic multiplets. As a bonus, some of the models produce a one-loop neutrino Dirac mass if a right-handed neutrino field is included, and some feature WIMP-like dark matter candidates. By way of example, we analyse the phenomenology of a benchmark model chosen from the set of 25 candidates and find that it is capable of exactly replicating the predicted Standard Model Yukawa couplings within the permitted parameter space.

hep-ph

Higgs Yukawa coupling constraints on a benchmark one-loop radiative mass model for the bottom, charm and tau

Measurements of Higgs boson Yukawa couplings to Standard Model (SM) fermions constrain radiative mass models for those species. Such models, motivated by the observed fermion mass hierarchy, act as foils for the SM tree-level mechanism: we cannot claim to have verified the standard mechanism if other possibilities also fit the data well. We construct a benchmark model which generates the top mass at tree level, and the bottom, charm, tau, and tau Dirac neutrino masses at one-loop level. Current theoretical and experimental constraints on the model, including from Higgs decays, demonstrate it possesses viable regions of parameter space. We show that future improvements to measurements will not be able to rule out the model, only increase the scale of new physics required, illustrating how difficult it will be to verify the SM fermion mass generation mechanism with great precision. As a bonus, a dark matter candidate is shown to be capable of reproducing the correct relic density within the permitted parameter space.

hep-ph