An analysis is carried out within mSUGRA of the estimated number of events originating from upward moving ultra-high energy neutralinos passing through Earth ’ s crust that could be detected by the Extreme Universe Space Observatory ( EUSO ) .
The analysis exploits a recently proposed technique that differentiates ultra-high energy neutralinos from ultra-high energy neutrinos using their different absorption lengths in the Earth ’ s crust .
It is shown that for the part of the parameter space , where the neutralino is mostly a Bino and with squark mass \sim 1 TeV , EUSO could see ultra-high energy neutralino events within mSUGRA models with essentially no background .
In the energy range 10 ^ { 9 } ~ { } { GeV } < E _ { \tilde { \chi } } < 10 ^ { 11 } ~ { } { GeV } the unprecedented aperture of EUSO makes the telescope sensitive , after 3 yr of observation , to neutralino fluxes as low as d \Phi / dE _ { \tilde { \chi } } > 1.1 \times 10 ^ { -6 } ( E _ { \tilde { \chi } } / { GeV } ) ^ { -1.3 } GeV ^ { -1 } cm ^ { -2 } yr ^ { -1 } sr ^ { -1 } , at the 95 % CL .
Such a hard spectrum is characteristic of supermassive particles ’ N -body hadronic decay .
The case in which the flux of ultra-high energy neutralinos is produced via decay of metastable heavy ( m _ { X } = 2 \times 10 ^ { 12 } GeV ) particles with uniform distribution throughout the universe , and primary decay mode into 5 quarks + 5 squarks , is analyzed in detail .
The normalization of the ratio of the relics ’ density to their lifetime has been fixed so that the baryon flux produced in the supermassive particle decays contributes to about 1/3 of the events reported by the AGASA Collaboration below 10 ^ { 11 } GeV , and hence the associated GeV \gamma -ray flux is in complete agreement with EGRET data .
For this particular case , EUSO will collect between 4 and 5 neutralino events ( with 0.3 of background ) in \approx 3 yr of running .
NASA ’ s planned mission , the Orbiting Wide-angle Light-collectors ( OWL ) , is also briefly discussed in this context .