We perform a consistent analysis of the alternative left-right symmetric model emerging from E 6 grand unification. We include a large set of theoretical and experimental constraints, with a particular emphasis on dark matter observables and collider signals. We show that the exotic neutrino inherent to this class of models, the scotino, is a viable candidate for dark matter satisfying relic density and direct detection constraints. This has strong implications on the scotino mass restricting it to lie in a narrow window, as well as on the spectrum of Higgs bosons, rendering it predictable, with a few light scalar, pseudoscalar and charged states. Moreover, we also show that the extra charged W gauge boson can be light, and investigate the most promising signals at the future high-luminosity upgrade of the LHC. Our findings show that the most optimistic cosmologically-favoured scenarios should be observable at 5σ, whilst others could leave visible hints provided the background is under good control at the systematical level. SU (2) L × SU (2) H × U (1) X group that embeds the SU (2) L × U (1) Y electroweak symmetry. In the so-called left-right symmetric model (LRSM), that naturally accounts for non-vanishing neutrino masses [20][21][22][23], SU (2) H is identified with SU (2) R and U (1) X with U (1) B−L . In such a configuration, the right-handed SM fermions and the right-handed neutrino ν R are collected into SU (2) R doublets. The structure of the Higgs sector could however lead to non-acceptable tree-level flavour-violating interactions that would conflict with the observed properties of kaon and B-meson systems. Consequently, the SU (2) R × U (1) B−L symmetry has to be broken at a very high energy scale to mass-suppress any potential flavour-violating effect. This additionally pushes the masses of the extra Higgs and gauge bosons of the model to the high scale, making them unlikely to detect at the LHC. Furthermore, in its minimal incarnation, the LRSM lacks any viable DM candidate [24].It is nevertheless possible to associate the SU (2) H symmetry with a different SU (2) R group in which the assignments of the SM fermions into doublets are different [25,26]. This model is called the alternative left-right symmetric model (ALRSM) [27,28]. In this case, the SU (2) R partner of the right-handed up-quark u R is an exotic down-type quark d R (instead of the SM right-handed down-type quark d R ), and the SU (2) R partner of the right-handed charged lepton e R is a new neutral lepton, the scotino n R (instead of the more standard right-handed neutrino ν R ). The righthanded neutrino ν R and down-type quark d R therefore remain singlets under both the SU (2) L and SU (2) R groups. In addition, the model field content also includes SU (2) L singlet counterparts to the new states, i.e. an n L scotino and a d L down-type quark. Consequently, one generation of quarks is described by one SU (2) Similarly, one generation of leptons is described by one SU (2) L doublet L L = (ν L , e L ), one SU (2) R doublet L R = (n R ,...

We explore the low-scale implications of the Pati-Salam Model including the TeV scale right-handed neutrinos interacting and mixing with the MSSM fields through the inverse seesaw (IS) mechanism in light of the muon anomalous magnetic moment (muon g − 2) resolution and highlight the solutions which are compatible with the quasi-Yukawa unification condition (QYU). We find that the presence of the righthanded neutrinos causes heavy smuons as mμ ≳ 800 GeV in order to avoid tachyonic staus at the low scale. On the other hand, the sneutrinos can be as light as about 100 GeV, and along with the light charginos of mass ≲400 GeV, they can yield such large contributions to muon g − 2 that the discrepancy between the experiment and the theory can be resolved. These solutions also require m˜χAE We also discuss such light chargino and neutralino along with the light stau (mτ ≳ 200 GeV) in the light of current LHC results. Besides, the gluino mass lies in a range ∼½2.5-3.5 TeV, which is tested in near future experiments. In addition, the model predicts relatively light Higgsinos (μ ≲ 700 GeV); hence, the second chargino mass is also light enough (≲700 GeV) to contribute to muon g − 2. Light Higgsinos also yield less fine-tuning at the electroweak scale, and the regions compatible with muon g − 2 restrict Δ EW ≲ 100 strictly, and this region also satisfies the QYU condition. In addition, the ratios among the Yukawa couplings should be 1.8 ≲ y t /y b ≲ 2.6, y τ /y b ∼ 1.3 to yield correct fermion masses. Even though the righthanded neutrino Yukawa coupling can be varied freely, the solutions bound its range to 0.8 ≲ y ν /y b ≲ 1.7.

We investigate the predictions on the mass spectrum and Higgs boson decays in the supersymmetric standard model extended by U (1) B−L symmetry (BLSSM). The model requires two singlet Higgs fields, which are responsible for the radiative breaking of U (1) B−L symmetry. It predicts degenerate right-handed neutrino masses (1.7 − 2.2 TeV) as well as the right-handed sneutrinos of mass 4 TeV. The presence of right-handed neutrinos and sneutrinos trigger the baryon and lepton number violation processes, until they decouple from the Standard model particles. Besides, the model predicts rather heavy colored particles; mt, mb 1.5 TeV, while mτ 100 GeV and mχ± 1 600 GeV. Even though, the implications are similar to minimal supersymmetric standard model, BLSSM can predict another Higgs boson lighter than 150 GeV. We find that the second Higgs boson can be degenerate with the lightest CP-even Higgs boson of mass about 125 GeV and contribute to the Higgs decay into two photons. In addition, it can provide an explanation for the excess in h → 4l at the mass scale ∼ 145 GeV.

We test E 6 realisations of a generic U(1) extended Minimal Supersymmetric Standard Model (UMSSM), parametrised in terms of the mixing angle pertaining to the new U(1) sector, θ E 6 , against all currently available data, from space to ground experiments, from low to high energies. We find that experimental constraints are very restrictive and indicate that large gauge kinetic mixing and θ E 6 ≈ −π/3 are required within this theoretical construct to achieve compliance with current data. The consequences are twofold. On the one hand, large gauge kinetic mixing implies that the Z boson emerging from the breaking of the additional U(1) symmetry is rather wide since it decays mainly into W W pairs. On the other hand, the preferred θ E 6 value calls for a rather specific E 6 breaking pattern different from those commonly studied. We finally delineate potential signatures of the emerging UMSSM scenario in both Large Hadron Collider (LHC) and in Dark Matter (DM) experiments.

We study mass bounds of the WR gauge boson in generic left-right symmetric models. Assuming that the gauge bosons couple universally to quarks and leptons, we allow different gauge couplings gR = gL and mass mixing, V L CKM = V R CKM in the left and right sectors. Imposing constraints from collider experiments and K 0 , B d , Bs physics, we investigate scenarios where WR is lighter, or heavier than the right handed neutrino νR. In these scenarios, WR mass bounds can be considerably relaxed, while ZR mass bounds are much more stringent. In the case where MW R ≤ Mν R , the experimental constraints come from WR → tb and WR → jj channels, while if MW R ≥ Mν R , the dominant constraints come from WR → jj. The observed (expected) limits in the two-dimensional (MW R , Mν R ) mass plane excluded at 95% confidence level extend to approximately MW R = 3.1 (3.3) TeV in the ee channel and 3.3 (3.4) TeV in the (µµ) channel, for a large range of right-handed neutrino masses up to Mν R = 2.1 (2.1) TeV in the ee channel and 2.6 (2.5) in the (µµ) channel, representing a significant relaxation of the mass bounds. a