The model studied is a SUSY model with the lightest bosinos being higgsinos. Xi^0_2 and Xi^+-_1 are mass-degenerate, and very close ( ~ 1 GeV) in mass to Xi^0_1, which is the LSP. No other SUSY particles are assumed to be produced at ILC energies. The very low mass differences impies that the signal events resembles gammagamma events. Therefore, it is required that the signal events are acompagned by a detected ISR photon
This benchmark in particular can probe four features:
- Detection of very low pt tracks.
- Identifying these particles.
- Detecting, identifying and measuring ISR photons.
- Identifying and rejecting tracks for gammagamma→low pt hadrons and beam-strahlung.
In addition, as for any missing pt-signal, hermeticty is also important.
The main direct observables for the signal are the momentum and identity of the visible decay-products of bosino decays, and the properties of the ISR-photon. With these observations, the masses of the SUSY particles can be reconstructed. The physics observables are the masses of the three SUSY particles and the production cross-sections.
As a main background, also the properties of the gammagamma→low pt hadrons is a main output: Cross-sections, branching-ratios to different vector-mesons, production vertex position.
Previous study (partly based on SGV, no low-pt hadron and beam-strahlung overlay): 'Tackling light higgsinos at the ILC', EPJC (2013) 73:2660, arXiv:1307.3566