Search for new particles in the context of SUSY (Q2735026)

Despite very intensive research work at the high energy accelerators LEP, Tevatron and HERA, no sign of supersymmetry showed up so far. If the Higgs is supersymmetric and if the MSSM is realised in nature, its lightest Higgs, the \(h^0\), is expected to have a mass below about 125 GeV. From the data collected until 1998, the LEP experiment have excluded the existence of the \(h^0\) with a mass less than 95 GeV if its couplings are like a Standard Model Higgs and about 81 GeV in the more general MSSM case. From the very preliminary results of the 1999 run, the limit set by individual experiments increases to approximately 106 GeV for the SM-like \(h^0\). If the final analyses still do not show evidence for a discovery, the limit expected after combining the experiments should increase to 109 GeV. With the existing limitations to the energy of LEP, the maximum achievable in 2000 will be around \(\sqrt s=204-206\) GeV. It should then be possible, provided a sufficient luminosity can be delivered to the experiments, to explore the mass range up to about 114-115 GeV. This leaves a gap of only 10 GeV to prove or invalidate the MSSM in its current form. In the near future, this region may be probed at the Tevatron, if they manage to accumulate 20-30 \(fb^{-1}\) of luminosity. Else, the discovery of the Higgs will have to await the running of the LHC. As for the discovery of the superpartners predicted by supersymmetry, there exists no strong theoretical mass bound, like for the \(h^0\). Their mass could be anywhere below a few TeV. The LEP experiments will allow to explore the region up to about 100 GeV for most of them, be it in the framework of the MSSM with a stable neutralino as LSP, of Gauge Mediated Supersymmetry breaking, or of \(R\)-parity violation. A somewhat larger mass range can be probed, for limited values of the MSSM parameters, for squarks and gluons at the Tevetron and for leptoquarks at HERA. A huge virgin forest will most likely be left here for exploration at the LHC.NEWLINENEWLINEFor the entire collection see [Zbl 0944.00082].