First steps towards the search for evidence of split-SUSY at Auger.

P. HANSEN; S. J. SCIUTTO; J. ALVAREZ-MUÑIZ; T. PAUL; L. A. ANCHORDOQUI

2011-04-01/2012-02-15

1-23

Informática (software)

Prom.Gral.del Conoc.-Cs.Exactas y Naturales

There exist a number of new-physics scenerios which predict strongly interacting massiveparticles. If such particles constitute some fraction of the cosmic ray flux, they could induceunique shower morphologies which could be searched for in the data. Here, we consider oneparticular class of theories, namely split-SUSY, in order to eventually arrive at an estimate ofthe potential for a discovery or a bound in the context of this theory. Split-SUSY predicts longlived,massive supersymmetric particles called R-hadrons . The extremely low inelasticity ofthe R-hadrons in their collisions with air molecules results in a distinct shower characteristics.The leading particle retains most of its energy all the way to the ground, while the secondaryparticles promptly cascade to low energies as for any other air shower. This results in an ensembleof mini-showers strung along the trajectory of the leading particle. Since the typical distancebetween mini-showers is about 10 times smaller than the extent of a single longitudinal profile,it is not possible to resolve the individual showers experimentally. Instead one observesan envelope encompassing all the mini-showers with a significant electromagnetic componentat the ground. By selecting inclined showers the sensitivity to R-hadrons is enhanced. In thisGAP note we explore the characteristics of inclined showers induced by R-hadrons at the SurfaceDetector (SD) of the Pierre Auger Observatory and compare them to inclined proton andneutrino-induced showers (the background). This is a first preliminary work with the aim ofexploring observables capable of separating R-hadrons from background showers. We showthat R-hadron induced showers can be discriminated from proton-induced showers using aFisher Discriminant Method to establish cuts to maximize the identification efficiency. ThoughR-hadron and neutrino-induced showers are harder to separate, this is not an obstacle to placea limit on R-hadron production if no candidates are found. Though the study presented herewas conducted in the context of a specific theoretical model (split-SUSY), we emphasize thatthe techniques apply in general to any theory involving stable, long-lived strongly interactingparticles.