New astrophysical constraints on the mass of the superlight gravitino

In some supergravity models, the superlight gravitino is accompanied by a light weakly coupled scalar (S) and pseudoscalar particle (P). The couplings of these particles to matter (e.g. electrons and photons) is inversely proportional to the product (mgMPl) where mg and MPl are respectively the gravitino mass and the Planck mass. As a result, their emission from supernovae and stars via the reaction γ + e− → SP + e− for certain ranges of the gravitino mass can become the dominant energy loss mechanism in contradiction with observations thereby ruling out those mass values for the gravitino. For 10 MeV ≥ mSP ≥ keV, the SN1987A observations can be used to exclude the gravitino masses in the range (10−1.5 ≤ mg ≤ 30) eV, whereas if mSP ≤ keV, constraints of stellar energy loss can exclude the range (3 × 10−6 ≤ mg ≤ 50) eV for the photino mass equal to 100 GeV. We also find that if mSP ≤ MeV, present understanding of big bang nucleosynthesis imply that mg ≥ eV. These are the most severe bounds to date on mg in this class of models.