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Abbas, G. (2016). Right-right-left extension of the Standard Model. Mod. Phys. Lett. A, 31(19), 1650117–10pp.
Abstract: A right-right-left extension of the Standard Model is proposed. In this model, SM gauge group SU(2)(L) circle times U(1)(Y) is extended to SU(2)(L) circle times SU(2)(R) circle times SU(2)'(R) circle times SU(2)'(L) circle times U(1)(Y). The gauge symmetries SU(2)'(R), SU(2)'(L) are the mirror counterparts of the SU(2)(L) and SU(2)(R), respectively. Parity is spontaneously broken when the scalar Higgs fields acquire vacuum expectation values (VEVs) in a certain pattern. Parity is restored at the scale of SU(2)'(L). The gauge sector has a unique pattern. The scalar sector of the model is optimum, elegant and unique.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2013). Evidence for the spin-0 nature of the Higgs boson using ATLAS data. Phys. Lett. B, 726(1-3), 120–144.
Abstract: Studies of the spin and parity quantum numbers of the Higgs boson are presented, based on protonproton collision data collected by the ATLAS experiment at the LHC. The Standard Model spin-parity J(P) = 0(+) hypothesis is compared with alternative hypotheses using the Higgs boson decays H -> gamma gamma, H -> ZZ* -> 4l and H -> WW* -> l nu l nu, as well as the combination of these channels. The analysed dataset corresponds to an integrated luminosity of 20.7 fb(-1) collected at a centre-of-mass energy of root s = 8 TeV. For the H -> ZZ* -> 4l decay mode the dataset corresponding to an integrated luminosity of 4.6 fb(-1) collected at root s = 7 TeV is included. The data are compatible with the Standard Model J(P) = 0+ quantum numbers for the Higgs boson, whereas all alternative hypotheses studied in this Letter, namely some specific J(P) = 0(-), 1(+), 1(-), 2(+) models, are excluded at confidence levels above 97.8%. This exclusion holds independently of the assumptions on the coupling strengths to the Standard Model particles and in the case of the J(P) = 2(+) model, of the relative fractions of gluon-fusion and quark-antiquark production of the spin-2 particle. The data thus provide evidence for the spin-0 nature of the Higgs boson, with positive parity being strongly preferred.
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