相关论文: A custodial symmetry for Zbb

Integrating out a heavy scalar can cause the Higgs trilinear coupling to deviate from its Standard Model value: a good example is provided by an $SU(2)$ quadruplet. Constraints on the full theory, however, can limit the size of the…

We present a version of the twin Higgs mechanism with minimal symmetry structure and particle content. The model is built upon a composite Higgs theory with global $SO(6)/SO(5)$ symmetry breaking. The leading contribution to the Higgs…

The $SU(2){-}$gauged custodial two-Higgs-doublet model, which shares the same global-symmetry properties with the standard model, is studied non-perturbatively on the lattice. The additional Higgs doublet enlarges the scalar spectrum and…

We study how the custodial symmetry in the Higgs sector of the Georgi-Machacek (GM) model can be tested at the LHC. As the minimal extension of the Higgs triplet model, in which tiny neutrino masses are generated via the Type-II Seesaw…

We consider non-supersymmetric quiver theories obtained by orbifolding the N=4 supersymmetric U(K) gauge theory by a discrete Z_\Gamma group embedded in the SU(4) R-symmetry group. We explicitly find that in such theories there are no…

We show that the extension of the approximate custodial $SU(2)_{L+R}$ global symmetry to all the Yukawa interactions of the standard model Lagrangian implies the introduction of sterile right-handed neutrinos and the seesaw mechanism in…

We consider composite Higgs models where the Higgs is a pseudo-Nambu Goldstone boson arising from the spontaneous breaking of an approximate global symmetry by some underlying strong dynamics. We focus on the SO(5) -> SO(4) symmetry…

We propose an alternative to the introduction of an extra gauge (custodial) symmetry to suppress the contribution of KK modes to the T parameter in warped theories of electroweak breaking. The mechanism is based on a general class of warped…

Original Georgi-Machacek model can preserve the custodial symmetry at tree level after the electroweak symmetry breaking. Unless additional $SU(2)_c$ custodial symmetry breaking effects are significant, the new physics contributions to…

We discuss the results of a search for anomaly free Abelian Z_N discrete symmetries that lead to automatic R-parity conservation and prevents dangerous higher-dimensional proton decay operators in simple extensions of the minimal…

In theories with extra dimensions the Standard Model Higgs field can be identified with the internal components of higher-dimensional gauge fields (Higgs-gauge unification). The higher-dimensional gauge symmetry prevents the Higgs mass from…

A complete analysis of the electroweak precision observables is performed within a recently proposed minimal composite Higgs model, realized as a 5-dimensional warped compactification. In particular, we compute Z->bb and the one-loop…

The strongly interacting sector in the E6 inspired composite Higgs model (E6CHM) with baryon number violation possesses SU(6)\times U(1)_L global symmetry. In the weakly-coupled sector of this model the U(1)_L symmetry associated with…

We construct a little Higgs model with the most minimal extension of the standard model gauge group by an extra U(1) gauge symmetry. For specific charge assignments of scalars, an approximate U(3) global symmetry appears in the…

We argue that the consistent implementation of the multiple point principle (MPP) in the general non-supersymmetric two Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in…

Among the $Z$-pole observables, $A_{FB}^{(0,b)}$ and $A_e$ suffer moderately-large standard deviations from the Standard Model predictions. Fine-tuning of the unknown Higgs mass only reduces the deviation of one of them at the expense of…

It is shown that a gauged SO(3) family symmetry can suppress flavor-changing processes from squark-mass non-degeneracy to an acceptable level. The potentially dangerous SO(3) D-terms can be rendered harmless if the CP-violating phases…

The new measurement of the $W$-boson mass from the CDF collaboration shows a significant tension with the Standard Model prediction. We quantify this discrepancy within a state-of-the-art analysis of electroweak precision data and…

It has been observed that an automatic alignment without decoupling is predicted at tree-level in a Two-Higgs Doublet Model (2HDM) with extended supersymmetry in the gauge and Higgs sectors. Moreover, it was found that radiative corrections…

We introduce and systematically study an expansive class of "orbifold Higgs" theories in which the weak scale is protected by accidental symmetries arising from the orbifold reduction of continuous symmetries. The protection mechanism…