From the 1 of 7 linked papers with an AI index.
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astro-ph.CO2026
Primordial black holes through preheating instabilities in -attractor models
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar +2
The paper investigates how primordial black holes can form during the preheating phase after α‑attractor inflation, using instability criteria and comparing the Press‑Schechter and…
hep-th2026
Unitary Quadratic Quantum Gravity in 4D
K. Sravan Kumar, João Marto
In quadratic gravity, with a positive Weyl squared coefficient, the extra spin-2 sector is shown to correspond to a dual inverted harmonic oscillator, instead of a ghost. Using the…
hep-th2026
Quantum (quadratic) gravity: replacing the massive tensor ghost with an inverted harmonic oscillator-like instability
K. Sravan Kumar, João Marto
The quadratic theory of gravity is the unique renormalizable theory of quantum gravity in 4 dimensions, as proved by K. S. Stelle in 1977. Over the decades, the theory has been und…