Tokyo – Kavli Institute Pre-Print Publications

Stability of Branching Multiplicities for Orthogonal Gelfand Pairs

Posted by klaurent April 24, 2026April 27, 2026This Week: Astrophysics, Tokyo

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 […]

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Fermion Condensate Inflation, Dynamical Waterfall Mechanism and Primordial Black Holes

Posted by klaurent April 23, 2026April 27, 2026This Week: Astrophysics, Tokyo

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 […]

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Merger rate of initially clustered primordial black holes for the two-body channel

Posted by klaurent April 21, 2026April 27, 2026This Week: Astrophysics, Tokyo

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 […]

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The Atacama Cosmology Telescope: A Test of the Gravitational Force Law on Cosmological Scales Using the Kinematic Sunyaev-Zeldovich Effect

Posted by klaurent April 15, 2026April 27, 2026Tokyo

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 […]

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Fermion Multiplicities at the GUT Scale: A Statistical Study of Unification and Proton Decay

Posted by klaurent April 9, 2026April 21, 2026Tokyo

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 […]

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Detecting Chiral Gravitational Wave Background with a Dipole Pulsar Timing Array

Posted by klaurent April 9, 2026April 21, 2026Tokyo

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 […]

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Electroweak Doublet Dark Matter for a Galactic Halo Gamma-Ray Excess

Posted by klaurent April 6, 2026April 21, 2026Tokyo

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 […]

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Resolutions and deformations of cyclic quotient surface singularities

Posted by klaurent April 6, 2026Tokyo

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 […]

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A Closer Look at Constrained Instantons

Posted by klaurent April 3, 2026April 14, 2026Tokyo

Kavli Affiliate: Satoshi Shirai | Summary:Instantons play a crucial role in understanding non-perturbative dynamics in quantum field theories, including those with spontaneously broken gauge symmetries. In the broken phase, finite-size instanton-like configurations are no longer exact stationary points of the Euclidean action, in contrast to the symmetric phase. Non-perturbative effects in this setting are therefore […]

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Spectroscopic confirmation of dual and offset quasars from the Subaru HSC-SSP program

Posted by klaurent April 2, 2026Tokyo

Kavli Affiliate: John Silverman | Summary:We present a spectroscopic follow-up program targeting closely-separated dual quasar candidates selected from imaging of SDSS quasars with the Subaru Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using two-dimensional image decomposition, our selection identifies PSF-like companions within 0.6-4 arcsec separation (< 30 kpc) around the SDSS quasar. We newly confirm six […]

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