Kavli Affiliate: Toshiyuki Kobayashi | Summary:This expository paper explains, in the case of $mathfraksl_2$, the ideas introduced in the preprints (arXiv:2509.17007, 2604.22262), which develop a new framework for the study of multiplicities in branching laws of representations, with particular emphasis on their dependence on representation parameters. Taking the Lie algebra $mathfraksl_2$ as a guiding example, […]
Kavli Affiliate: Toshiyuki Kobayashi | Summary:We propose a structural framework for branching multiplicities in representation theory, emphasizing their behavior under variation of infinitesimal characters. For the orthogonal reductive pairs $(G,G’)$ with complexified Lie algebras $(mathfrako(n+1,mathbbC), mathfrako(n,mathbbC))$, we show that branching multiplicities are governed by universal systems of linear inequalities on the parameter space of reduced […]
Kavli Affiliate: Misao Sasaki | Summary:Fermion condensate inflation, where inflation emerges from four-fermion interactions induced by spacetime torsion, removes the need for additional scalar fields beyond the Standard Model. In this framework, the fermion field can be decomposed into two distinguished sectors, each giving rise to bound states. After integrating out fermions, the bound fields […]
Kavli Affiliate: Masahiro Kawasaki | Summary:Primordial black holes (PBHs) may form an initially clustered population depending on their production mechanism. Motivated by binary black-hole merger events observed by gravitational-wave interferometers, we revisit the evaluation of the merger rate of PBH binaries and extend the formalism to include the effects of clustering. We show that, in […]
Kavli Affiliate: David Spergel | Summary:The mean pairwise velocity of massive halos reflects the gravitational force law on cosmic scales. We combine cosmic microwave background intensity maps from the Atacama Cosmology Telescope and a galaxy catalog from the Sloan Digital Sky Survey to estimate the mean pairwise velocity using the kinematic Sunyaev-Zeldovich (kSZ) effect. On […]
Kavli Affiliate: Satoshi Shirai | Summary:We study the impact of multiple vector-like fermions in SU(5) grand unified theory (GUT). Threshold effects from extra fermions allow the observed gauge couplings to be consistently matched to a single unified gauge coupling, and typically raise the unification scale to $M_mathrmGUTsimeq 10^15.5,mathrmGeV$. Because the Standard Model fermions arise as […]
Kavli Affiliate: Misao Sasaki | Summary:The pulsar timing array (PTA) is a powerful technique for detecting nanohertz gravitational wave backgrounds (GWBs). However, conventional PTAs lack sensitivity to parity violation in the GWB. In this work, we propose a dipole pulsar timing array system (dPTA). By deriving the overlap reduction functions (ORFs) from the cross-correlation of […]
Kavli Affiliate: Yasunori Nomura | Summary:Weakly interacting massive particles provide a well-motivated framework for dark matter, naturally reproducing the observed relic abundance through thermal freeze-out. A recent claim of an indirect-detection signal from the Galactic halo, consistent with dark matter annihilation in the mass range 400–800 GeV, motivates a reexamination of minimal models that can […]
Kavli Affiliate: Yukari Ito | Summary:In this paper, we investigate the relations among various results concerning the minimal resolution of cyclic quotient singularities of the form $mathbbC^2/G$. We refer to these as "bamboo-type" singularities, since the dual graphs of the exceptional curves in their resolutions resemble the shape of bamboo. We present classical results on […]
Kavli Affiliate: Yukari Ito | Summary:In this paper, we investigate the relations among various results concerning the minimal resolution of cyclic quotient singularities of the form $mathbbC^2/G$. We refer to these as "bamboo-type" singularities, since the dual graphs of the exceptional curves in their resolutions resemble the shape of bamboo. We present classical results on […]