Generic and Chiral Extensions of the Supersymmetric Standard Model

TL;DR

The paper addresses how Planck-scale physics could induce dangerous operators in the MSSM and proposes extending the gauge sector with an anomaly-free $U(1)_\mu$ that both forbids such operators and communicates SUSY breaking to the MSSM via gauge mediation. A three-sector, anomaly-consistent framework is developed, comprising the MSSM, a messenger sector, and a dynamical SUSY-breaking (DSB) sector, with four viable messenger patterns characterized by $(\Delta\beta_3, \Delta\beta_2, \Delta\beta_1)$ that fix gaugino mass relationships and ensure ultraviolet consistency. The resulting phenomenology features a calculable sparticle spectrum with distinctive NLSP possibilities, including an $SU(2)_W$-neutralino NLSP and a singletino NLSP, leading to novel collider signatures such as $WW\not\!E_T$, $Wγ\not\!E_T$, and $WZ\not\!E_T$ that could be probed at hadron colliders. While providing a self-contained alternative to conventional gauge-mediated models with automatic $R$-parity conservation and neutrino masses, the work also leaves open questions about fermion mass textures, the strong CP problem, unification, and vacuum stability.

Abstract

We construct extensions of the Standard Model in which the gauge symmetries and supersymmetry prevent the dangerously large effects that may potentially be induced in a supersymmetric standard model by Planck scale physics. These include baryon number violation, flavor changing neutral currents, the $μ$ term, and masses for singlet or vector-like fields under the Standard Model gauge group. For this purpose we introduce an extra non-anomalous $U(1)_μ$ gauge group. Dynamical supersymmetry breaking in a secluded sector triggers the breaking of the $U(1)_μ$ and generates soft masses for the superpartners via gauge mediation, with the scalars possibly receiving sizable contributions from the $U(1)_μ$ D-term. We find several classes of complete and calculable models, in which the messengers do not present cosmological problems and neutrino masses can also be accomodated. We derive the sparticle spectrum in these models and study the phenomenological consequences. We give an exhaustive list of the potential experimental signatures and discuss their observability in the upcoming Tevatron runs. One class of models exhibits interesting new discovery channels, namely $WW \not E_T$, $Wγ\not E_T$ and $WZ \not E_T$, which arise when the next-to-lightest supersymmetric particle is a short-lived $SU(2)_W$ neutralino.

Figures (1)

• Figure 2: Sample diagrams for the possible decay modes of $\tilde{\chi}^0_3$ to the singletino NLSP $\tilde{\chi}^0_1$.