We study an inevitable cosmological consequence in PeV-scale SUSY-breaking scenarios. We focus on the SUSY-breaking scale corresponding to the gravitino mass m3/2=100eV–1keV. We argue that the presence of an early matter-dominated era and the resulting entropy production are requisite for the Universe with this gravitino mass. We infer the model-independent minimum amount of the entropy production Δ by requiring that the number of dwarf satellite galaxies Nsat in the Milky Way exceed the currently observed value, i.e., Nsat≳63. This entropy production is inevitably imprinted on the primordial gravitational waves (PGWs) produced during the inflationary era. We study how the information on the value of Δ and the time of entropy production are encoded in the PGW spectrum ΩGW. If the future GW surveys observe a suppression feature in the PGW spectrum for the frequency range O(10−10)Hz≲fGW≲O(10−5)Hz, it works as a smoking gun for PeV SUSY-breaking scenarios. Even if they do not, our study can be used to rule out all such scenarios.

• Received 4 August 2021
• Accepted 23 October 2021

DOI:https://doi.org/10.1103/PhysRevD.104.095018

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society