Primordial non-Gaussianity from ultra slow-roll Galileon inflation
Choudhury S. Karde A. Panda S. Sami M.
1 January 2024Institute of Physics
Journal of Cosmology and Astroparticle Physics
2024#2024Issue 1
We present a detailed study of the generation of large primordial non-Gaussianities during the slow-roll (SR) to ultra-slow roll (USR) transitions in the framework of Galileon inflation. We found out that due to having sharp transitions in the USR phase, which persist with a duration of ΔNUSR ∼ 2 e-folds, we are able to generate the non-Gaussianity amplitude of the order: |f NL| ∼ o(10-2) in the SRI, -5 < f NL < 5 in the USR, and -2 < f NL < 2 in the SRII phases. As a result, we are able to achieve a cumulative average value of |f NL| ∼ o(1). This implies that our results strictly satisfy Maldacenas no-go theorem in the squeezed limit only for SRI, while they strictly violate the same condition in both the USR and SRII phases. The non-renormalization theorem in the Galileon theory helps to support our results regarding the generation of large mass primordial black holes along with large non-Gaussianities, which we show to be dependent on the specific positions of the transition wave numbers fixed at low scales.
cosmological perturbation theory , inflation , physics of the early universe , string theory and cosmology
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Centre For Cosmology and Science Popularization (CCSP), SGT University, Haryana, Gurugram, Delhi-NCR, 122505, India
Center for Theoretical Physics, Eurasian National University, Astana, 010008, Kazakhstan
Chinese Academy of Sciences, 52 Sanlihe Rd, Xicheng District, Beijing, China
Centre For Cosmology and Science Popularization (CCSP)
Center for Theoretical Physics
Chinese Academy of Sciences
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