Scrutinizing the lightest supersymmetric particle dark matter at the CERN LHC

We show that CERN LHC experiments might well be able to determine ail the parameters required for a prediction of the present density of thermal LSP relies from the big bang era. If the LSP is an almost pure B-ino we usually only need to determine its mass and the mass of the SU(2) singlet sleptons. This information can be obtained by reconstructing the cascade (q) over tilde (L)-->(chi )over tilde>(0)(2)q-->(l) over tilde (R)lq--><()over tilde>(0)(1)l(+l-)q. The only requirement is that m (l) over tildeR<(chi )over bar>(0)(2), which is true for most of the cosmologically interesting parameter space. If the LSP has a significant Higgsino component, its predicted thermal relic density is smaller than for an equal-mass B-ino, We show that in this case squark decays also produce significant numbers of <()over tilde>(0)(4) and <()over tilde>(+/-)(2). Reconstructing the corresponding decay cascades then allows us to determine the Higgsino component of the LSP.