Identifying Unconventional E$_{\bf 6}$ Models at $e^+ e^-$ Colliders

We study the neutralino mass spectra and production cross sections at an e^+e^- linear collider in superstring-inspired E_6 models. These models are characterized by the existence of new neutral gauge bosons and singlet Higgs fields which also lead to an extended neutralino sector compared to the Minimal Supersymmetric Standard Model (MSSM) or the Next-To-Minimal Supersymmetric Standard Model (NMSSM). For different E_6 models we develop scenarios with new light exotic neutral...

We examine the processes $e^+ e^-\longrightarrow W^+ W^-$ and $Z^0 Z^0$ in the context of the $SP(6)_L\otimes U(1)_Y$ model. We find that there are significant deviations in the total cross sections $\sigma (s)$ from the standard model results due to the presence of additional gauge bosons $Z^\prime$ and $W^\prime$ in the model. These deviations could be detected at LEP.

We consider a minimal renormalizable non-supersymmetric $E_6$ Grand Unified Theory using only fundamental representation $27$ for fermions and scalars. The proposed model, guided by TeV-scale vector-like fermions and scalars offer successful gauge unification even in the absence of any intermediate symmetry. Embedded with threshold corrections, it is shown to be compatible with the present experimental limit on proton decay lifetime. The unique feature of the model shows that...

The $E_6$SSM extension of the MSSM allows for the solution of many of the difficulties that are usually encountered within conventional SUSY breaking scenarios, e.g., the $\mu$ problem, the imposition of R-parity 'by hand', the generation of light neutrino masses and obtaining a light Higgs boson with a mass as large as $\sim$ 125 GeV as suggested by recent LHC measurements. In addressing these problems, such a scenario predicts the existence of additional singlet and vector-...

We present a self--consistent $E_6$ inspired supersymmetric model with an extra $U(1)_{N}$ gauge symmetry under which right-handed neutrinos have zero charge. We explore the particle spectrum within the constrained version of this exceptional supersymmetric standard model (E$_6$SSM) and discuss its possible collider signatures.

In gauge-Higgs unification (GHU), the 4D Higgs boson appears as a part of the fifth dimensional component of 5D gauge field. Recently, an $SO(11)$ GUT inspired $SO(5)\times U(1)\times SU(3)$ GHU model has been proposed. In the GHU, Kaluza-Klein (KK) excited states of neutral vector bosons, photon, $Z$ boson and $Z_R$ boson, appear as neutral massive vector bosons $Z'$s. The $Z'$ bosons in the GHU couple to quarks and leptons with large parity violation, which leads to distinc...

We present an $E_6$ Grand Unified model with a realistic pattern of fermion masses. All standard model fermions are unified in three fundamental 27-plets (i.e. supersymmetry is not invoked), which involve in addition right handed neutrinos and three families of vector like heavy quarks and leptons. The lightest of those can lie in the low TeV range, being accessible to future collider experiments. Due to the high symmetry, the masses and mixings of all fermions are closely re...

Supersymmetric (SUSY) grand unified theories based on exceptional gauge groups such as E6 have recently triggered a lot of interest. Aside from top-down motivations, they contain phenomenologically interesting states with leptoquark quantum numbers. Their SUSY partners, leptoquarkinos, will appear similar to all R-odd particles in decay cascades, but mass edges in kinematic distributions- originating from the same semiexclusive final states-will however have major differences...

We propose a solution to the recent $W$ mass measurement by embedding the Standard Model within $E_6$ models. The presence of a new $U(1)$ group shifts the $W$ boson mass at the tree level and introduces a new gauge boson $Z^{\prime}$ which has been searched for at collider experiments. In this article, we identity the parameter space that explains the new $W$ mass measurement and is consistent with current experimental $Z^{\prime}$ searches. As $U(1)$ extensions can be accom...

We discuss the prospects for setting limits on or discovering spin-1 $Z'$ bosons using early LHC data at 7 TeV. Our results are based on the narrow width approximation in which the leptonic Drell-Yan $Z'$ boson production cross-section only depends on the $Z'$ boson mass together with two parameters $c_u$ and $c_d$. We carefully discuss the experimental cuts that should be applied and tabulate the theoretical next-to-next-to-leading order corrections which must be included. U...