Sparticle Spectroscopy and Electroweak Symmetry Breaking with Gauge-Mediated Supersymmetry Breaking

TL;DR

This work analyzes gauge-mediated supersymmetry breaking (GMSB) with the minimal messenger sector, deriving a highly predictive sparticle spectrum from radiative electroweak symmetry breaking and gauge-mediated boundary conditions. The authors perform a two-loop RG analysis, detailing how the spectrum at the weak scale depends primarily on Λ = F/S and tanβ, with A-terms suppressed and Higgs-sector parameters fixed by EWSB minimization. They identify mass relations and sum rules that distinguish MGM from other SUSY-breaking schemes, and show how the messenger scale M induces logarithmic sensitivities in certain mass ratios. Phenomenologically, MGM predicts a lightest SM superpartner that is either Bino-like χ⁰₁ or a right-handed slepton, with potential decays to the Goldstino inside detectors, and distinctive collider signatures including missing energy or heavy charged tracks; non-minimal messenger sectors can yield alternative spectra, such as a slepton NLSP or Higgsino-like states, while precision flavor constraints remain modest.

Abstract

The phenomenology associated with gauge-mediated supersymmetry breaking is presented. A renormalization group analysis of the minimal model is performed in which the constraints of radiative electroweak symmetry breaking are imposed. The resulting superpartner and Higgs boson spectra are highly correlated and depend on only a few parameters. Superpartner mass ratios and sum rules are identified which can be tested at future colliders. Some of these relations are logarithmically sensitive to the messenger scale, while others allow gauge-mediation to be distinguished from other schemes for tansmitting supersymmetry breaking. Deviations from the minimal model, such as larger messenger representations and additional contributions to Higgs sector masses, can in some circumstances dramatically modify the low energy spectrum. These modifications include a slepton or Higgsino as the lightest standard model superpartner, or exotic mass relations among the scalars and gauginos. The contribution to $b \to s γ$ and resulting bound on superpartner masses are also presented for the minimal model. Finally, the unique collider signatures of heavy charged particle production, or decay to the Goldstino within a detector are discussed.

Figures (21)

• Figure 1: One-loop messenger sector supergraph which gives rise to visible sector gaugino masses.
• Figure 2: Two-loop messenger sector supergraph which gives rise to visible sector scalar masses. The one-loop subgraph gives rise to visible sector gaugino wave function renormalization. Other graphs related by gauge invariance are not shown.
• Figure 3: One-loop visible sector supergraph which contains both logarithmic and finite contributions to visible sector $A$-terms. The cross on the visible sector gaugino line represents the gaugino mass insertion shown in Fig. 1.
• Figure 4: Renormalization group evolution of the $\overline{\rm DR}$ mass parameters with MGM boundary conditions. The messenger scale is $M=76\hbox{\rm,TeV}$, $m_{\tilde{B}}(M)=115\hbox{\rm,GeV}$, $\tan\beta =3$, ${\rm sgn}(\mu) = +1$, and $m_t^{\rm pole} = 175$ GeV. The masses are plotted as $m \equiv {\rm sgn}(m) (|m|)^{1/2}$.
• Figure 5: The relation between $m_2$ and $|\mu|$ imposed by electroweak symmetry breaking with MGM boundary conditions for $\tan\beta =2,3,5,10,30$, and $\Lambda=M$.