https://doi.org/10.1140/epjc/s10052-025-14176-z
Regular Article - Theoretical Physics
Negative non-Gaussianity as a salvager for PBHs with PTAs in bounce
1
Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
2
Centre for Cosmology and Science Popularization (CCSP), SGT University, Gurugram, 122505, Delhi-NCR, Haryana, India
3
Indian Institute of Science Education and Research, 140306, Mohali, India
a sayanphysicsisi@gmail.com, schoudhury@fuw.edu.pl, sayantan.choudhury@nanograv.org
Received:
28
December
2024
Accepted:
10
April
2025
Published online:
30
April
2025
Non-Gaussianity in the primordial curvature perturbation is a crucial element of the early universe due to its significant impact on the primordial black hole (PBH) production. In this work, we focus on the effects of negative non-Gaussianity on PBH abundance through the lens of the compaction function criterion for PBH formation. Our setup utilizes an effective field theory of non-singular bounce, including the standard slow-roll inflation with an ultra-slow roll phase for amplifying the curvature perturbations to form PBHs. We investigate with two separate values of the non-Gaussianity parameter, 
, found within the ekpyrotic contraction and the matter bounce scenarios, respectively, and show that a negatively large amount of 
can provide sizeable abundance, 
, and completely mitigates the PBH overproduction issue. We also highlight that the case with the effective sound speed 
, coupled with 
, provides an agreement under 
for the scalar-induced gravitational wave explanation of the latest PTA (NANOGrav15 and EPTA) signal. Lastly, we extract an upper bound on the most negative value of, 
, below which we show breaching of the underlying perturbativity constraints on the power spectrum amplitude.
© The Author(s) 2025
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Funded by SCOAP3.
