Yuichiro Tada, IPMU
Stochastic-delta N formalism and massive primordial black holes in hybrid inflation
Meeting Room 1, Kenkyu Honkan 1F
As a long-studied astrophysical open question, it is known that almost all galaxies possess one or a few supermassive black holes (SMBHs) whose masses reach 10^{6—9.5} M_\odot in their centers. Such SMBHs have been found even at high redshifts as z~6–7 but their production mechanism is still unknown. One possible solution is the primordial black hole (PBH), which is theoretically suggested to be produced by a gravitational collapse of an overdense Hubble patch in the radiation dominant era. It has been proposed that sufficient massive PBHs can be the seeds of SMBHs. In our recent papers, we studied the possibility whether such massive PBHs can be produced in well-know hybrid inflation which is the inflation model ended by a second order phase transition. While that phase transition is roughly estimated to make large curvature perturbations enough to produce PBHs, there have been no quantitatively complete works yet because of the non-perturbative behavior around the critical point. Therefore, we proposed a non-perturbative algorithm to calculate the curvature perturbations at first, combining the stochastic and delta N formalism. Then we performed a wide numerical parameter search to find that PBHs are rather overproduced with the parameters which can make PBHs massive enough. In other words, we showed that massive PBHs cannot be produced with the proper abundance in hybrid inflation, without any specific assumption of the types of hybrid inflation.
Nobuhito Maru, Osaka City University
Predictions of Higgs mass and Weinberg angle in 6D gauge-Higgs unification
Meeting Room 1, Kenkyu Honkan 1F We address a question whether there exists a model of gauge-Higgs unification in 6-dimensional space-time, which successfully predicts the Weinberg angle and the mass ratios between Higgs boson and weak gauge bosons.
We address a question whether there exists a model of gauge-Higgs unification in 6-dimensional space-time, which successfully predicts the Weinberg angle and the mass ratios between Higgs boson and weak gauge bosons.
First, we give a general argument on the condition to get a realistic prediction of the Weinberg angle, and find that triplet and sextet representations of the minimal SU(3) gauge group lead to the realistic prediction.
We notice that in the models with one Higgs doublet, the predicted Higgs mass is always twice the W-boson mass at the leading order.
However, in models with two Higgs doublets, Higgs mass can be smaller than twice the W-boson mass.
Nilakash Sorokhaibam, TIFR
2D Critical Quench, Thermalization and Non-Universality
Meeting room 3, Kenkyu honkan 1F
