Supersymmetric Analysis and Predictions Based on the Collider Detector at Fermilabeeγγ+MissingEnergyEvent

Abstract

We have analyzed the single eeγγ + / E T event at CDF and found that the expected rate and kinematics are consistent with selectron pair production. We consider two classes of general low-energy supersymmetric theories, where either the lightest neutralino ("neutralino LSP" scenario) or the gravitino ("light gravitino" scenario) is the lightest supersymmetric particle. The parameter space of the supersymmetric Lagrangian is tightly constrained by the kinematics of the event and the branching ratios for the necessary decay chain of the selectron. We identify a region of the parameter space satisfying all low-energy constraints, and consistent with the selectron interpretation of the eeγγ + / E T event. We discuss other supersymmetric processes at Fermilab Tevatron and at CERN LEP in both scenarios that could confirm or exclude a supersymmetric explanation of the event, and that could distinguish between the neutralino LSP and the light gravitino scenarios. * Supported by a INFN postdoctoral fellowship, Italy.

Status of Precision Tests of the Standard Model

“…But it is a single event and even an extremely unlikely possibility can occur once. Several papers have already been devoted to this event [93] . In SUSY models two main possibilities have been investigated.…”

Search for stable heavy charged particles in e+e− collisions at , 161 and 172 GeV

“…I n a n umber of these models sleptons, in particular staus, may h a v e su ciently long lifetimes i n a v ery natural way, so that they should be visible as stable charged particles in the detector [3]. For selectrons, the contribution via t-channel neutralino exchange has to be taken into account.…”

“…In models where the neutralino is the LSP, this situation can occur for charginos if the light c hargino and the LSP are almost degenerate. In models where the gravitino is the LSP [3], sleptons can obtain long lifetimes in a very natural way [4], especially the staus, the superpartners of the tau lepton.…”

Disrupting the one-loop renormalization group invariant M/α in supersymmetry

“…Although the simplest supergravity models and gauge-mediated models suggest such a relation should hold near the weak scale, it is nevertheless prudent to study other alternatives (four quite different examples of models with that are not expected to have "unified" gaugino masses can be found in Refs. [31,32,28,33]). Consider a model with gaugino masses M ′ a ≡ k a M a , such that…”