6 papers
New Bounds on Heavy QCD Axions from Big Bang Nucleosynthesis
Tae Hyun Jung, Takemichi Okui, Kohsaku Tobioka +1
We study Big Bang Nucleosynthesis (BBN) constraints on heavy QCD axions. BBN offers a powerful probe of new physics that modifies the neutron-to-proton ratio during the process, th…
Dynamics of the Fermion-Rotor System
Vazha Loladze, Takemichi Okui, David Tong
We explore the dynamics of the fermion-rotor system, a simple impurity model in d=1+1 dimensions that consists of a collection of purely right-moving fermions interacting with a qu…
Irreducible Bhabha background in the detection of muonium-antimuonium conversion
Mitrajyoti Ghosh, Kevin Liguori, Takemichi Okui +1
Experiments such as MACS and the proposed MACE study muonium-antimuonium conversion by the energies of the final-state . The and from an antimuonium decay tend t…
Neutrino properties from muonium-antimuonium mixing
Mitrajyoti Ghosh, Kevin Liguori, Takemichi Okui +1
The nature of neutrino mass -- whether neutrinos are Dirac or Majorana particles -- remains one of the central open questions in particle physics. While observation of neutrinoless…
Monopole-Fermion Scattering and the Solution to the Semiton/Unitarity Puzzle
Vazha Loladze, Takemichi Okui
We study Polchinski's "fermion-rotor system" as an accurate description of charged Weyl fermions scattering on a magnetic monopole core in the limit of zero gauge coupling. Traditi…
Primordial black holes from bubble collisions during a first-order phase transition
Tae Hyun Jung, Takemichi Okui
We study the possibility of production of primordial black holes (PBHs) from bubble collisions during a first-order phase transition. While typical colliding bubbles are small and…