Z−Z′mass hierarchy in a supersymmetric model with a secludedU(1)

Abstract

We consider the Z ′ /Z mass hierarchy in a supersymmetric model in which the U (1) ′ is broken in a secluded sector coupled to the ordinary sector only by gauge and possibly soft terms. A large mass hierarchy can be achieved while maintaining the normal sparticle spectra if there is a direction in which the tree level potential becomes flat when a particular Yukawa coupling vanishes. We describe the conditions needed for the desired breaking pattern, to avoid unwanted global symmetries, and for an acceptable effective µ parameter. The electroweak breaking is dominated by A terms rather than scalar masses, leading to tan β ≃ 1. The spectrum of the symmetry breaking sector is displayed. There is significant mixing between the MSSM particles and new standard model singlets, for both the Higgs scalars and the neutralinos. A larger Yukawa coupling for the effective µ parameter is allowed than in the NMSSM because of the U (1) ′ contribution to the running from a high scale. The upper bound on the tree-level mass of the lightest CP even Higgs doublet mass is about c×174 GeV, where c is of order unity, but the actual mass eigenvalues are generally smaller because of singlet mixing.

Heavy neutral gauge bosons at the LHC in an extended MSSM

“…θ = arccos 5/8 − π/2, leads to a neutral boson which will be referred to as Z ′ I . Furthermore, in the so-called secluded model, a U(1) ′ S model extends the MSSM with a singlet field S [24]. The connection with the E 6 groups is achieved assuming a mixing angle θ = arctan( √ 15/9) − π/2 and a gauge boson Z ′ S .…”

Collider signatures of singlet extended Higgs sectors

“…7 We assume gaugino mass unification. 8 There are cases where the indirect detection rates of neutralino dark matter can be enhanced in these models by a light CP-odd Higgs boson [24]. 9 Additionally, an analysis of the Higgs signal at LEP in a model independent way places a lower bound on the Higgs mass at 81 GeV [25].…”

“…The models we focus on include the Next-to-Minimal Supersymmetric SM (NMSSM) [2], the Nearly-Minimal Supersymmetric SM (nMSSM) [3,4,5], and the U(1) ′ -extended MSSM (UMSSM) [6], as detailed in Table I with the respective symmetries 1 . A Secluded U(1) ′ -extended MSSM (sMSSM) [8,9] contains three singlets in addition to the standard UMSSM Higgs singlet; this model is equivalent to the nMSSM in the limit that the additional singlet vevs are large, and the trilinear singlet coupling, λ s , is small [10]. The nMSSM and sMSSM will therefore be referred to together as the n/sMSSM.…”

Search for gauge extensions of the MSSM at the LHC

“…Which of these options is realized depends on the Uð1Þ 0 charge assignments and the soft-breaking masses in the Higgs sector (see [28] for a variant reducing the Z À Z 0 mixing).…”