149 citations · 671 across the 50 of their papers we have counts for
8 papers · 1 filter
PBH formation from overdensities in delayed vacuum transitions
Kiyoharu Kawana, TaeHun Kim, Philip Lu
Primordial black hole (PBH) formation from first-order phase transitions (FOPTs) combines two prevalent elements of beyond the Standard Model physics with wide-ranging consequences…
Late-Forming PBH: Beyond the CMB era
Philip Lu, Kiyoharu Kawana, Alexander Kusenko
The intermediate mass black hole range, , has long offered enticing possibilities for primordial black holes (PBH), with popula…
Baby universes in 2d and 4d theories of quantum gravity
Yuta Hamada, Hikaru Kawai, Kiyoharu Kawana
The validity of the Coleman mechanism, which automatically tunes the fundamental constants, is examined in two-dimensional and four-dimensional quantum gravity theories. First, we…
Entropy and its conservation in expanding Universe
Sinya Aoki, Kiyoharu Kawana
We investigate properties of the conserved charge in general relativity, recently proposed by one of the present authors with his collaborators, in the inflation era, the matter do…
First-order phase transition and fate of false vacuum remnants
Kiyoharu Kawana, Philip Lu, Ke-Pan Xie
False vacuum remnants in first-order phase transitions in the early Universe can form compact objects which may constitute dark matter. Such remnants form because particles develop…
Gravitational waves in models with multicritical-point principle
Yuta Hamada, Hikaru Kawai, Kiyoharu Kawana +2
The multicritical-point principle (MPP) provides a natural explanation of the large hierarchy between the Planck and electroweak scales. We consider a scenario in which MPP is appl…
Old Phase Remnants in First Order Phase Transitions
Philip Lu, Kiyoharu Kawana, Ke-Pan Xie
First order phase transitions (FOPTs) are usually described by the nucleation and expansion of new phase bubbles in the old phase background. While the dynamics of new phase bubble…
Cosmology of Supercooled Universe
Kiyoharu Kawana
First-order phase transitions (FOPTs) are ubiquitous in physics beyond the Standard Model (SM). Recently, models with no dimensionful parameters in the tree-level action have been…