Higgs Bosons in supersymmetric U(1)' models with CP Violation

We study the Higgs sector of the U(1)'-extended MSSM with CP violation. This is an extension of the MSSM Higgs sector by one singlet field, introduced to generate the \mu term dynamically. We are particularly interested in non-standard decays of Higgs particles, especially of the lightest one, in the presence of CP violating phases for \mu_{eff} and the soft parameters. We present analytical expressions for neutral and charged Higgs bosons masses at tree and one-loop levels, including contributions from top and bottom scalar quark sectors. We then study the production and decay channels of the neutral Higgs for a set of benchmark points consistent with low energy data and relic density constraints. Numerical simulations show that a Higgs boson lighter than 2m_W can decay in a quite distinctive manner, including invisible modes into two neutralinos (h->\chi^0\chi^0) up to 50% of the time, when kinematically allowed. The branching ratio into h->bb, the dominant decay in the SM, is reduced in some U(1)' models and enhanced in others, while the branching ratios for the decays h -> \tau+ \tau-, h -> WW^* and h -> Z Z^*-> 4l are always reduced with respect to their SM expectations. This possibility has important implications for testing the U(1)' model both at the LHC and later at the ILC.Comment: 35 pages, 5 tables, 4 figure

Sneutrino Dark Matter: Symmetry Protection and Cosmic Ray Anomalies

We present an R-parity conserving model of sneutrino dark matter within a Higgs-philic U(1)' extension of the minimal supersymmetric standard model. In this theory, the mu parameter and light Dirac neutrino masses are generated naturally upon the breaking of the U(1)' gauge symmetry. The leptonic and hadronic decays of sneutrinos in this model, taken to be the lightest and next-to-lightest superpartners, allow for a natural fit to the recent results reported by the PAMELA experiment.Comment: Revised to match the published version; 11 pages (2 column format), 1 table, 6 figures, to appear in PR

Trilinear Higgs couplings in the two Higgs doublet model with CP violation

We carry out a detailed analysis of the general two Higgs doublet model with CP violation. We describe two different parametrizations of this model, and then study the Higgs boson masses and the trilinear Higgs couplings for these two parametrizations. Within a rather general model, we find that the trilinear Higgs couplings have a significant dependence on the details of the model, even when the lightest Higgs boson mass is taken to be a fixed parameter. We include radiative corrections in the one-loop effective potential approximation in our analysis of the Higgs boson masses and the Higgs trilinear couplings. The one-loop corrections to the trilinear couplings of the two Higgs doublet model also depend significantly on the details of the model, and can be rather large. We study quantitatively the trilinear Higgs couplings, and show that these couplings are typically several times larger than the corresponding Standard Model trilinear Higgs coupling in some regions of the parameter space. We also briefly discuss the decoupling limit of the two Higgs doublet model.Comment: 23 pages, 15 figures. v2: References added, version to appear in PR

Model Characterization and Dark Matter in the Secluded U(1)′ Model

We consider a class of U(1)'-extended MSSM in which the U(1)' symmetry is broken by a vacuum expectation values (VEVs) of four MSSM singlet fields. While one singlet field interacts with the MSSM Higgs fields, three of them interact only with each other in forming a secluded sector. Assigning universal U(1)' charges for three families, the anomaly cancellation condition requires exotic fields which are assumed to be heavy and decoupled. We discuss a variety of U(1)' charge assignments and anomaly cancellation, Z'/Z hierarchy, neutralinos and charginos as well as the Higgs sector. We realize that the typical spectra involve two CP-odd Higgs bosons lighter than about 200 GeV and 600 GeV respectively, which are mostly formed by the MSSM singlet fields. If the relic density of dark matter is saturated only by a neutralino, compatible solutions predict LSP neutralinos formed by the MSSM singlet fields in the mass scales below about 600 GeV, while it is possible to realize MSSM neutralino LSP above these mass scales. We identify A-funnel solutions in the MSSM singlet LSP solutions. These solutions can also yield considerable scattering cross-sections through the Higgs portal such that they can be tested in the ongoing direct dark matter detection experiments

Charged higgs boson in MSSM and beyond

We conduct a numerical study over the constrained MSSM (CMSSM), next-to-MSSM (NMSSM) and U(1) extended MSSM (UMSSM) to probe the allowed mass ranges of the charged Higgs boson and its dominant decay patterns, which might come into prominence in the near future collider experiments. We present results obtained from a limited scan for CMSSM as a basis and compare its predictions with the extended models. We observe within our data that a wide mass range is allowed as 0.5(1) less than or similar to m(H)(+/-) less than or similar to 17 TeV in UMSSM (NMSSM). We find that the dominant decay channel is mostly (H-+/- -> tb) such that BR(H-+/- -> tb) similar to 80%. While this mode remains dominant over the whole allowed parameter space of CMSSM, we realize some special domains in the NMSSM and UMSSM, in which BR(H-+/- -> tb) less than or similar to 10%. In this context, the decay patterns of the charged Higgs can play a significant role to distinguish among the SUSY models. In addition to the tb decay mode, we find that the narrow mass scale in CMSSM allows only the decay modes for the charged Higgs boson to tau nu (similar to 16%), and their supersymmetric partners (tau) over tilde(nu) over tilde (similar to 13%). On the other hand, it is possible to realize the mode in NMSSM and UMSSM in which the charged Higgs boson decays into a chargino and neutralino pair up to about 25%. This decay mode requires nonuniversal boundary conditions within the MSSM framework to be available, since CMSSM yields BR(H-+/- -> (chi) over tilde (1)(0)) less than or similar to. 1%. It can also be probed in the near future collider experiments through the missing energy and CP-violation measurements. Moreover, the chargino mass is realized as m((chi) over tilde1)(+/-) TeV in NMSSM and UMSSM, and these solutions will be likely tested soon in collider experiments through the chargino-neutralino production. Focusing on the chargino-neutralino decay patterns, we also present tables which list the possible ranges for the charged Higgs production and decay modes.Balıkesir Üniversitesi - BAP-2017/142 - BAP-2017/174Ankara Üniversitesi - 17B044300

Neutralino and chargino production in

We examine the production and decay modes of neutralinos and charginos in a softly-broken supersymmetric model with an extra Abelian symmetry U(1)′. We perform the study in 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 SU(2) singlet fields into the model. Although the chargino sector is the same as in the MSSM, the neutralino sector of the model is very rich: five new fermion fields are added to the neutral sector bring the total neutralino states to nine. We implement the model into standard packages and perform a detailed and systematic analysis of production and decay modes at the LHC, for three different scenarios, consistent with the Higgs data and relic density constraints. We concentrate on final signals (1) $1\ell+\mathit{jets}+\not\! \! E_{T}$, (2) $2\ell+\mathit{jets}+\not\! \! E_{T}$ and (3) $3\ell+0\mathit{jets}+\not\! \! E_{T}$, and comment on the case with $0\ell+\mathit{jets}+\not\! \! E_{T}$. We discuss backgrounds and indicate how these signals can be observed, and how the model can be distinguished from other supersymmetric model scenarios

Scalar neutrinos at the LHC

We study a softly broken supersymmetric model whose gauge symmetry is that of the standard model gauge group times an extra Abelian symmetry U(1)'. We call this gauge-extended model the U(1)' model, and we study a U(1)' model with a secluded sector such that neutrinos acquire Dirac masses via higher-dimensional terms allowed by the U(1)' invariance. In this model the mu term of the minimal supersymmetric model (MSSM) is dynamically induced by the vacuum expectation value of a singlet scalar. In addition, the model contains exotic particles necessary for anomaly cancellation, and extra singlet bosons for achieving correct Z'/Z mass hierarchy. The neutrinos are charged under U(1)', and thus, their production and decay channels differ from those in the MSSM in strength and topology. We implement the model into standard packages and perform a detailed analysis of sneutrino production and decay at the Large Hadron Collider, for various mass scenarios, concentrating on three types of signals: (1) 0l + MET, (2) 2l + MET, and (3) 4l + MET. We compare the results with those of the MSSM whenever possible, and analyze the standard model background for each signal. The sneutrino production and decays provide clear signatures enabling distinction of the U(1)' model from the MSSM at the LHC