Neutralino and chargino production in U(1)′ at the LHC

Abstract

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) 1ℓ + jets+ E T , (2) 2ℓ + jets+ E T and (3) 3ℓ + 0 jets+ E T , and comment on the case with 0ℓ + jets+ 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.

Heavy $$Z^\prime $$ bosons in the secluded $$U(1)^\prime $$ model at hadron colliders

“…This occurs across all 2 + E T , 4 + E T and 6 + E T signals and for all benchmarks. This confirms past analyses for 2 + E T [60,74], which indicated that, unless Z is leptophobic, and thus much lighter, the signal significance is small. However, that is not necessarily so at 27 or 100 TeV and across all signals.…”

“…The symmetry-breaking sector of the model is very complex, and finding an acceptable minimum of the Higgs potential, even at the tree level, is non-trivial [60]. Once a minimum is found, the mass of the lightest Higgs boson can be fine tuned to 125 GeV by small variations in the parameterh s .…”

“…The mass of the Z boson is, as usual, proportional to the VEV of the singlet Higgs boson S. But this parameter also determines the scale of the chargino/neutralino sector, thus a heavy Z implies a heavy electroweakino sector, reducing further the interest in such models at the LHC. To avoid this link, we work in a secluded scenario [59,60], where the scalar sector of the U (1) model is augmented by three additional singlet superfields 1 , whose role is to decouple the mass of the Z from the scale of chargino and neutralino masses. The disadvantage is extending the particle spectrum of the SM more than the conventional U (1) model, while the gain is being able to preserve a large Z mass while allowing light charginos/neutralinos, and in particular, a light dark matter candidate, which is the lightest supersymmetric particle (LSP).…”

Light neutralino dark matter inU(1)′models

“…In U(1) ′ models, the allowed Higgs mass ranges have to be reconsidered due to the additional quartic Higgs self-couplings from the D-terms. The masses obtained are generally larger, LEP bounds on Higgs bosons with SM-like couplings to the Z boson are easier to satisfy, and radiative corrections from top-stop loops as well as constraints from gauge coupling unification in different configurations for the Higgs spectrum can exist, and can satisfy the LHC bounds on the SM-like Higgs boson [34]. In what follows, we are concerned with the Higgs and neutralino sectors.…”

Testing the higgsino-singlino sector of the NMSSM with trileptons at the LHC

“…There, the absence of significant excesses of events is interpreted in simplified models, motivated by the SUSY particle content of the Minimal SUSY extension of the Standard Model (MSSM) and assuming simple branching ratios and relations among masses. Interpretations of the present constraints from the trilepton channel in realistic versions of the MSSM have been performed in [18][19][20][21] (see [22][23][24] for the rôle of trilepton final states in some beyond-the-MSSM models).…”