Light Sgoldstino: Precision Measurements versus Collider Searches

We study sensitivity of low-energy experiments to the scale of supersymmetry breaking $\sqrt{F}$ in models with light sgoldstinos - superpartners of goldstino. The limits on $\sqrt{F}$ may be estimated from direct and indirect measurements of sgoldstino coupling to photons, leptons, mesons and nucleons. There are three sources of constraints: (i) astrophysics and cosmology; (ii) precision laboratory experiments at low energies; (iii) rare decays. We discuss only processes with real sgoldstinos. For sgoldstino lighter than a few MeV and superpartner masses of the order of electroweak scale, astrophysical and reactor bounds on $\sqrt{F}$ are significantly stronger than limits which may be reached at future colliders. In models with heavier sgoldstino (up to 5 GeV), constraints from flavor conserving decays of mesons are complementary to ones coming from collider experiments. The most sensitive probes of sgoldstinos are flavor violating processes, provided that flavor is violated in squark and/or slepton sector. It is shown that sgoldstino contributions into FCNC and lepton flavor violation are strong enough to place a bound $\sqrt{F}\gtrsim10^7$ TeV assuming off-diagonal entries in squark (slepton) mass matrices equal to their current limits in MSSM