Probing split supersymmetry with cosmic rays

Abstract

A striking aspect of the recently proposed split supersymmetry is the existence of heavy gluinos which are metastable because of the very heavy squarks which mediate their decay. In this paper we correlate the expected flux of these particles with the accompanying neutrino flux produced in inelastic pp collisions in distant astrophysical sources. We show that an event rate at the Pierre Auger Observatory of approximately 1 yr −1 for gluino masses of about 500 GeV is consistent with existing limits on neutrino fluxes. Such an event rate requires powerful cosmic ray engines able to accelerate particles up to extreme energies, somewhat above 5 × 10 13 GeV. The extremely low inelasticity of the gluino-containing hadrons in their collisions with the air molecules makes possible a distinct characterization of the showers induced in the atmosphere. Should such anomalous events be observed, we show that their cosmogenic origin, in concert with the requirement that they reach the Earth before decay, leads to a lower bound on their proper lifetime of the order of 100 years, and consequently, to a lower bound on the scale of supersymmetry breaking, Λ SUSY > 2.6 × 10 11 GeV. Obtaining such a bound is not possible in collider experiments.

Large D-terms, hierarchical soft spectra and moduli stabilisation

“…(11)(12)(13)(14) give the modified expressions for the soft terms after including non-zero D-type SUSY breaking contributions in supergravity. Whereas the scalar couplings receive corrections from the D-type terms, the gaugino masses are unaffected by D-mediated effects.…”

“…Instead, it is sufficient if the fermionic superpartners stay close to the weak scale, whereas the scalar superpartners can be present at scales as high as 10 9 GeV. This way, one keeps the nice features of gauge coupling unification and the viable dark matter candidate of low energy supersymmetry, while getting rid of unwanted features associated with large flavour changing neutral current effects and CP violation problems [11]. In section IV, we address the question of attaining split supersymmetry by including D-mediation.…”

TeVγrays and neutrinos from photodisintegration of nuclei in Cygnus OB2

“…In the pp mode, the resulting γ-ray spectrum is broad, reflecting the presence of a quasi-Feynman plateau which spans the entire rapidity space. The photon spectrum will deviate from the proton spectrum if the Feynman plateau is not flat in rapidity space [4], as suggested by Tevatron data [5]. Finally, for both the pγ and pp modes, the decay of the charged pions yield a neutrino counterpart with energy and intensity similar to the photons.…”

“…Therefore, if the TeV γ-ray signal from the Cygnus OB2 region can be explained by de-excitation of daughter nuclei after photo-dissociation, the neutrino population will be, in general, dominated by pion decay. However, with a significant population of 4 He, this may not be the case: through photo-dissociation 4 He only contributes to the ν e -flux without affecting the photon signal. Photon production from 4 He p interactions are negligible, see Eq.…”

Hadronic production and decays of charginos and neutralinos in split supersymmetry

“…[1], the first unique feature is the stable or metastable gluino. It may give rise to stable charged tracks [14,15,16] or gluinonium [17] signatures. We focus on the neutralino pair, chargino pair, and neutralino-chargino pair production, and their decays at hadron colliders.…”