No Arabic abstract
If the Higgs boson is a pseudo Nambu-Goldstone boson (PNGB), the $hZgamma$ contact interaction induced by the $mathcal{O}(p^4)$ invariants of the non-linear sigma model is free from its nonlinearity effects. The process $hrightarrow Zgamma$ can be used to eliminate the universal effects of heavy particles, which can fake the nonlinearity effects of the PNGB Higgs boson in the process $hrightarrow V^*V$ ($V=W^pm$, $Z$). We demonstrate that the ratio of the signal strength of $hrightarrow Zgamma$ and $hrightarrow V^*V$ is good to distinguish the signature of the PNGB Higgs boson from Higgs coupling deviations.
Motivated by recent constructions of TeV-scale strongly-coupled dynamics, either associated with the Higgs sector itself as in pseudo-Nambu-Goldstone boson (pNGB) Higgs models or in theories of asymmetric dark matter, we show that stable solitonic Q- balls can be formed from light pion-like pNGB fields carrying a conserved global quantum number in the presence of the Higgs field. We focus on the case of thick-wall Q-balls, where solutions satisfying all constraints are shown to exist over a range of parameter values. In the limit that our approximations hold, the Q-balls are weakly bound and parametrically large, and the form of the interactions of the light physical Higgs with the Q-ball is determined by the breaking of scale symmetry.
The idea to have Higgs doublets as pseudo Nambu-Goldstone (PsNG) multiplet is examined in the framework of supersymmetric E_6 unified theory. We show that extra PsNG multiplets other than the expected Higgs doublets necessarily appear in the E_6 case. If we demand that the extra PsNG multiplets neither disturb the gauge coupling unification nor make the color gauge coupling diverge before unification occurs, only possibility for the extra PsNG is 10+bar{10} of SU(5). This is realized when the symmetry breaking E_6 to SO(10) occurs in the phi(27)+phi(bar{27}) sector while E_6 to SU(4)_Ctimes SU(2)_Ltimes U(1)times U(1) in the Sigma(78) sector. The existence of 10+bar{10} multiplets with mass around 1 TeV is therefore a prediction of this E_6 PsNG scenario. Implication of their existence on the proton decay is also discussed.
We present a lattice calculation of $L_{10}$, one of the low energy constants in Chiral Perturbation Theory, and the charged-neutral pion squared mass splitting, using dynamical overlap fermion. Exact chiral symmetry of the overlap fermion allows us to reliably extract these quantities from the difference of the vacuum polarization functions for vector and axial-vector currents. In the context of the technicolor models, these two quantities are read as the $S$-parameter and the pseudo-Nambu-Goldstone boson mass respectively, and play an important role in discriminating the models from others. This calculation can serve as a feasibility study of the lattice techniques for more general technicolor gauge theories.
The notion that the scalar listed as $f_0 (500)$ in the particle data booklet is a pseudo-Nambu-Goldstone (NG) boson of spontaneously broken scale symmetry, explicitly broken by a small departure from an infrared fixed point, is explored in nuclear dynamics. That notion which puts the scalar -- that we shall identify as a dilaton -- on the same footing as the pseudo-scalar pseudo-NG bosons, i.e., octet $pi$, while providing a simple explanation for the $Delta I=1/2$ rule for kaon decay, generalizes the standard chiral perturbation theory (S$chi$PT) to scale chiral perturbation theory, denoted $chi$PT$_sigma$, with {it one infrared mass scale for both symmetries}, with the $sigma$ figuring as a chiral singlet NG mode in non-strange sector. Applied to nuclear dynamics, it is seen to provide possible answers to various hitherto unclarified nuclear phenomena such as the success of one-boson-exchange potentials (OBEP), the large cancellation of strongly attractive scalar potential by strongly repulsive vector potential in relativistic mean field theory of nuclear systems and in-medium QCD sum rules, the interplay of the dilaton and the vector meson $omega$ in dense skyrmion matter, the BPS skyrmion structure of nuclei accounting for small binding energies of medium-heavy nuclei, and the suppression of hyperon degrees of freedom in compact-star matter.
Within the supersymmetric SO(10) grand unified theory (GUT), a new mechanism, giving the light Higgs doublet as a pseudo-Goldstone mode, is suggested. Realizing this mechanism, we present an explicit model with fully realistic phenomenology. In particular, desirable symmetry breaking and natural all-order hierarchy are achieved. The constructed model allows one to have a realistic fermion pattern, nucleon stability, and successful gauge coupling unification. The suggested mechanism opens prospects in the field for a novel $SO(10)$ GUT model building and for further investigations.