The idea of left-right symmetry with mirror fermions is very appealing from the symmetry point of view. In this picture, unlike the Standard Model, the symmetry is not only left-right symmetric, but each left handed fermion multiplet is accompanied by new right handed fermion multiplet of opposite chirality. In this work, we consider a gauge symmetry, SU (3) c ⊗ SU (2) L ⊗ SU (2) R ⊗ U (1) Y ′ supplemented by a discrete Z 2 symmetry. Instead of having right handed multiplets for each left handed multiplets of the same fermions as in the usual left-right model, the mirror model include right handed doublets involving new fermions (called mirrors), and similarly for each right handed singlet, there are corresponding mirror singlets. Thus the gauge anomaly is naturally absent in this model, and the model also provide a solution for the strong CP problem because of parity conservation. The first stage of symmetry breaking is achieved by a doublet mirror Higgs with a vacuum expectation value ≃ 10 7 GeV, needed to explain the neutrino mass ≃ 10 −11 GeV. The mirror fermions can mix with the ordinary fermions via a scalar which is singlet under the gauge symmetry. In this model, only light mirror particles, having masses in the few hundred GeV range areê,û,d with well-defined spectrum.û andd can be pair produced at the LHC, and can be detected as (u Z) and (d Z) resonances. We discuss the signals of these mirror fermions at the LHC, and find that the reach at the LHC can be as large as mq ≃ 800 GeV.
Observation of non-zero neutrino masses at a scale ∼ 10 −1 − 10 −2 eV is a major problem in the otherwise highly successful Standard Model. The most elegant mechanism to explain such tiny neutrino masses is the seesaw mechanism with right handed neutrinos. However, the required seesaw scale is so high, ∼ 10 14 GeV, it will not have any collider implications. Recently, an explicit model has been constructed to realize the seesaw mechanism with the right handed neutrinos at the electroweak scale. The model has a mirror symmetry having both the left and right lepton and quark doublets and singlets for the same SU (2) W gauge symmetry. Additional Higgs multiplets have been introduced to realize this scenario. It turns out that these extra Higgs fields also help to satisfy the precision electroweak tests, and other observables. Because the scale of the symmetry breaking is electroweak, both the mirror quark and mirror leptons have masses in the electroweak scale in the range ∼ 150 − 800 GeV. The mirror quarks / leptons decay to ordinary quarks /leptons plus very light neutral scalars. In this work, we calculate the final state signals arising from the pair productions of these mirror quarks and their subsequent decays. We find that these signals are well observable over the Standard Model background for 13 TeV LHC. Depending on the associated Yukawa couplings, these decays can also give rise displaced vertices with long decay length, very different from the usual displaced vertices associated with b decays.
We propose a non-supersymmetric SU(5) model in which only the third family of fermions are unified. The model remedies the non-unification of the three Standard Model couplings in non-supersymmetric SU(5). It also provides a mechanism for baryon number violation which is needed for the baryon asymmetry of the Universe and is not present in the Standard Model. Current experimental constraints on the leptoquark gauge bosons, mediating such baryon and lepton violating interactions in our model, allow their masses to be at the TeV scale. These can be searched for as a (b\tau) or (tt) resonance at the Large Hadron Collider as predicted in our model.Comment: Title changed, some changes in text and figures. Published in Phys. Lett.
The existence of tiny neutrino masses at a scale more than a million times smaller than the lightest charged fermion mass, namely the electron, and their mixings can not be explained within the framework of the exceptionally successful Standard Model(SM).Several mechanisms were proposed to explain the tiny neutrino masses, most prominent among which is the so-called seesaw mechanism. Many models were built around this Additional signals will be the presence of displaced vertices depending on the smallness of the Yukawa couplings of the mirror leptons with the ordinary leptons and the singlet Higgs present in the model. Of particular importance to the EW-scale ν R model is the production of ν R which will be a direct test of the seesaw mechanism at collider energies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.