192 citations · 2.3k across the 49 of their papers we have counts for
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Tachyonic particle production: quantum 2PI formalism with momentum exchanging collisions
Kimmo Kainulainen, Sami Nurmi, Olli Väisänen
Oscillating spacetime curvature can drive particle production during reheating, whose accurate modeling requires the use of non-perturbative out-of-equilibrium methods. Tachyonic i…
Tachyonic production of dark relics: classical lattice vs. quantum 2PI in Hartree truncation
Kimmo Kainulainen, Sami Nurmi, Olli Väisänen
We study the out-of-equilibrium production of non-minimally coupled self-interacting scalar dark matter during reheating using classical lattice simulations. The outcomes of the cl…
Tachyonic production of dark relics: a non-perturbative quantum study
Kimmo Kainulainen, Olli Koskivaara, Sami Nurmi
We study production of dark relics during reheating after the end of inflation in a system consisting of a non-minimally coupled spectator scalar field and the inflaton. We derive…
Higgs-like spectator field as the origin of structure
Alexandros Karam, Tommi Markkanen, Luca Marzola +3
We show that the observed primordial perturbations can be entirely sourced by a light spectator scalar field with a quartic potential, akin to the Higgs boson, provided that the fi…
Radio signatures from encounters between Neutron Stars and QCD-Axion Minihalos around Primordial Black Holes
Sami Nurmi, Enrico D. Schiappacasse, Tsutomu T. Yanagida
Probing the QCD axion dark matter (DM) hypothesis is extremely challenging as the axion interacts very weakly with Standard Model particles. We propose a new avenue to test the QCD…
Shining Primordial Black Holes
Mark P. Hertzberg, Sami Nurmi, Enrico D. Schiappacasse +1
We study the well-motivated mixed dark matter (DM) scenario composed of a dominant thermal WIMP, highlighting the case of triplet fermion "winos", with a small fraction o…