Neutralino pair production at CERN LHC

We consider the production of neutralino pairs χ-tildei0χ-tildej0 at a high energy hadron collider, putting a special emphasis on the case where one of them is the lightest neutralino χ-tilde10, possibly constituting the main dark matter component. At tree level, the only relevant subprocess is qq-bar→χ-tildei0χ-tildej0, while the subprocess gg→χ-tildei0χ-tildej0 first appears at the one loop level. Explicit expressions for the qq-bar-helicity amplitudes are presented, including the tree level contributions and the leading-log one loop radiative corrections. For the one-loop gg→χ-tildei0χ-tildej0 process, a numerical code named PLATONggnn is released, allowing the computation of dσ/dt in any MSSM model with real soft breaking parameters. It turns out that acceptable MSSM benchmark models exist for which the qq-bar and the gluonic contributions may give comparable effects at LHC, due to the enhanced gluonic structure functions at low fractional momenta. Depending on the values of the MSSM parameters, we find that the LHC neutralino pair production may provide sensitive tests of SUSY models generating neutralino dark matter