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Register a new userCopositivity criteria, scalar mass eigenstates, and custodial symmetry parameter $Delta rho$ for the $S_3 otimes mathbb{Z}_2$ model
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We present the copositivity criteria for the scalar sector of our $S_3 otimes mathbb{Z}_2$ model, which ensures that it is bounded from below. We also show the scalar mass eigenstates, and identify the Standard Model Higgs boson among these by imposing that its Yukawa couplings are the same in our model and the Standard Model. The $Delta rho$ parameter, related to the custodial symmetry, is calculated as well.
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We present a model with $S_3 otimes mathbb{Z}_2$ model plus a sterile neutrino and its phenomenological expectations for the production of charged scalars at the Compact Linear Collider. At tree level, our model predicts a total cross section in between 0.1 and $10^{-5}$ pb for the $e^- e^+ to H^+ H^-$ process, considering all possible mass values for the charged scalar in the CLIC experiment. We also show that this prediction holds regardless of the masses of the other exotic particles and their couplings.
We consider an analogue of Wittens $SL(2,mathbb{Z})$ action on three-dimensional QFTs with $U(1)$ symmetry for $2k$-dimensional QFTs with $mathbb{Z}_2$ $(k-1)$-form symmetry. We show that the $SL(2,mathbb{Z})$ action only closes up to a multiplication by an invertible topological phase whose partition function is the Brown-Kervaire invariant of the spacetime manifold. We interpret it as part of the $SL(2,mathbb{Z})$ anomaly of the bulk $(2k+1)$-dimensional $mathbb{Z}_2$ gauge theory.
We discuss the recent results on the muon anomalous magnetic moment in the context of new physics models with light scalars. We propose a model in which the one-loop contributions to g-2 of a scalar and a pseudoscalar naturally cancel in the massless limit due to the symmetry structure of the model. This model allows to interpolate between two possible interpretations. In the first interpretation, the results provide a strong evidence of the existence of new physics, dominated by the positive contribution of a CP-even scalar. In the second one, supported by the recent lattice result, the data provides a strong upper bound on new physics, specifically in the case of (negative) pseudoscalar contributions. We emphasize that tree-level signatures of the new degrees of freedom of the model are enhanced relative to conventional explanations of the discrepancy. As a result, this model can be tested in the near future with accelerator-based experiments and possibly also at the precision frontier.
We investigate precision observables sensitive to custodial symmetric/violating UV physics beyond the Standard Model. We use the SMEFT framework which in general includes non-oblique corrections that requires a generalization of the Peskin-Takeuchi $T$ parameter to unambiguously detect custodial symmetry/violation. We take a first step towards constructing a SMEFT reparameterization-invariant replacement, that we call $mathscr{T}$, valid at least for tree-level custodial violating contributions. We utilize a new custodial basis of $ u$SMEFT (SMEFT augmented by right-handed neutrinos) which explicitly identifies the global $SU(2)_R$ symmetries of the Higgs and fermion sectors, that in turn permits easy identification of higher-dimensional operators that are custodial preserving or violating. We carefully consider equation-of-motion redundancies that cause custodial symmetric operators in one basis to be equivalent to a set of custodial symmetric and/or violating operators in another basis. Utilizing known results about tree/loop operator generation, we demonstrate that the basis-dependent appearance of custodial-violating operators does not invalidate our $mathscr{T}$ parameter at tree-level. We illustrate our results with several UV theory examples, demonstrating that $mathscr{T}$ faithfully identifies custodial symmetry violation, while $T$ can fail.
We propose a 2-Higgs doublet model where the symmetry is extended by $S_{3}otimes Z_{3}otimes Z_{3}^{prime }otimes Z_{14}$ and the field content is enlarged by extra $SU(2)_{L}$ singlet scalar fields. $S_3$ makes the model predictive and leads to viable fermion masses and mixing. The observed hierarchy of the quark masses arises from the $Z_{3}^{prime }$ and $Z_{14}$ symmetries. The light neutrino masses are generated through a type I seesaw mechanism with two heavy Majorana neutrinos. In the lepton sector we obtain mixing angles that are nearly tri-bi-maximal, in an excellent agreement with the observed lepton parameters. The vacuum expectation values required for the model are naturally obtained from the scalar potential, and we analyze the scalar sector properties further constraining the model through the $gamma gamma$ decay channel and the $T$ and $S$ parameters.
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