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Register a new userFamily Non-Universal U(1)$^prime$ Model with Minimal Number of Exotics
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We have studied phenomenological implications of several family non-universal U(1)$^prime$ sub-models in the U(1)$^prime$-extended Minimal Supersysmmetric Standard Model (UMSSM) possesing an extra down quark type exotic field. In doing this, we have started by enforcing anomaly cancellation criteria to generate a number of solutions in which the extra U(1)$^prime$ charges of the particles are treated as free parameters. We have then imposed existing bounds coming from colliders and astrophysical observations on the assumed sub-models and observed that current limits dictate certain charge orientations, for instance, $Q_{H_u}sim Q_{H_d}$ is preferred in general and the charge of the singlet $Q_S$ cannot be very small ($|Q_S|>$ 0.4) even if any of the charges is allowed to take any value within the $[-1, 1]$ range. We have finally studied the potential impact of such non-universal charges on $Z$ mediated processes and made predictions for existing and future experiments. It has turned out that UMSSMs with or without the presence of light exotic quarks can yield distinguisable signatures if non-universal charges are realised in the leptonic sector of such models.
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We analyse supersymmetric models augmented by an extra $U(1)$ gauge group. To avoid anomalies in these models without introducing exotics, we allow for family-dependent $U(1)^prime$ charges, and choose a simple form for these, dependent on one $U(1)^prime$ charge parameter only. With this choice, $Z^prime$ decays into di-taus but not di-leptons, weakening considerably the constraints on its mass. In the supersymmetric sector, the effect is to lower the singlino mass, allowing it to be the dark matter candidate. We investigate the dark matter constraints and collider implications of such models, with mostly singlino, or mostly higgsinos, or a mixture of the two as lightest supersymmetric particles. In these scenarios, $Z^prime$ decays significantly into chargino or neutralino pairs, and thus indirectly into final state leptons. We devise benchmarks which, with adequate cuts, can yield signals visible at the high-luminosity LHC.
Using newly available form factors obtained from light cone QCD sum rules in full theory, we study the flavor changing neutral current transition of $Sigma_b rar Sigma mu^+ mu^-$ decay in the family non-universal $Z^prime$ model. In particular, we evaluate the differential branching ratio, forward-backward asymmetry as well as some related asymmetry parameters and polarizations. We compare the obtained results with the predictions of the standard model and discuss the sensitivity of the observables under consideration to family non-universal $Z^prime$ gauge boson. The order of differential branching ratio shows that this decay mode can be checked at LHC in near future.
We study $Z$ phenomenology at hadron colliders in an $U(1)$ extended MSSM. We choose a $U(1)$ model with a secluded sector, where the tension between the electroweak scale and developing a large enough mass for $Z$ is resolved by incorporating three additional singlet superfields into the model. We perform a detailed analysis of the production, followed by decays, including into supersymmetric particles, of a $Z$ boson with mass between 4 and 5.2 TeV, with particular emphasis on its possible discovery. We select three different scenarios consistent with the latest available experimental data and relic density constraints, and concentrate on final signals with two leptons, four leptons and six leptons. Including the SM background from processes with two, three or four vector bosons, we show the likelihood of observing a $Z^prime$ boson is not promising for the HL-LHC at 14 TeV. While at 27 and 100 TeV, the situation is more optimistic, and we devise specific benchmark scenarios which could be observed.
So far the most sophisticated experiments have shown no trace of new physics at the TeV scale. Consequently, new models with unexplored parameter regions are necessary to explain current results, re-examine the existing data, and propose new experiments. In this Letter, we present a modified version of the $mu u$SSM supersymmetric model where a non-Universal extra U(1) gauge symmetry is added in order to restore an effective R-parity that ensures proton stability. We show that anomalies equations cancel without having to add emph{any} exotic matter, restricting the charges of the fields under the extra symmetry to a discrete set of values. We find that it is the viability of the model through anomalies cancellation what defines the conditions in which fermions interact with dark matter candidates via the exchange of $Z$ bosons. The strict condition of universality violation means that LHC constraints for a $Z$ mass do not apply directly to our model, allowing for a yet undiscovered relatively light $Z$, as we discuss both in the phenomenological context and in its implications for possible flavour changing neutral currents. Moreover, we explore the possibility of isospin violating dark matter interactions; we observe that this interaction depends, surprisingly, on the Higgs charges under the new symmetry, both limiting the number of possible models and allowing to analyse indirect dark matter searches in the light of well defined, particular scenarios.
We present semi-analytical solutions of the supersymmetric non-universal masses models for low $tanbeta$ regime. In addition to this, scale and $tanbeta$ dependencies of the soft (mass)$^2$ terms are given in the form of numerical solutions. By using the constrained form of the semi-analtic results, particular attention is paid on the non-universality assumption of the Higgs mass values and their potential measurable effects on the mass spectra of the minimal supersymmetric standard model. It is observed that, certain measurables are almost insensitive to the initial mass choices of the Higgs fields, like the mass of the light $mathcal{CP}$-even Higgs boson. On the other hand, large deviations exist on the mass of the remaining physical Higgs bosons signal that the allowed parameter space of the model can be probed successfully. For this aim, in addition to the other physical Higgs bosons, imprints originating from the heavier chargino ($tilde chi^pm_2$), heavy neutralinos ($tilde chi^0_3$, $tilde chi^0_4$) and the light scalar tau ($tilde tau_1$) are necessary and found to be promising.
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