Kyushu University · Physics and Astronomy
Professor Hajime Otsuka's research lab focuses on the interplay between string theory, algebraic geometry, and particle physics, particularly in the context of Calabi-Yau compactifications and F-theory compactifications. The lab investigates the geometrical origins of fundamental symmetries such as CP violation, flavor symmetries, and R-symmetries, exploring how these emerge from modular and symplectic structures in moduli spaces. A central theme is the dynamical stabilization of moduli fields near fixed points in the complex structure moduli space, with implications for fermion mass hierarchies and CP violation. The lab also pioneers the application of machine learning techniques to navigate the vast string landscape and identify phenomenologically viable three-generation models.
Figures are computed from collected data and may differ slightly.
We explore the geometrical origin of CP and the spontaneous CP violation in Calabi-Yau compactifications. We find that the CP symmetry is identified with an outer automorphism of the symplectic modular group in the large complex structure regime of Calabi-Yau threefolds, thereby enlarging the symplectic modular group to their semidirect product group. The spontaneous CP violation is realized by the introduction of fluxes, whose effective action is invariant under CP as well as the discrete Z2 sy
A bstract We examine a common origin of four-dimensional flavor, CP, and U(1) R symmetries in the context of heterotic string theory with standard embedding. We find that flavor and U(1) R symmetries are unified into the Sp(2 h + 2 , ℂ) modular symmetries of Calabi-Yau threefolds with h being the number of moduli fields. Together with the $$ {\mathbb{Z}}_2^{\mathrm{CP}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>ℤ</mml:mi> <mml:mn>2</mml:mn> <mml:mi>CP</mm
A bstract We study a symmetry breaking of residual flavor symmetries realized at fixed points of the moduli space. In the supersymmetric modular invariant theories, a small departure of the modulus from fixed points is required to realize fermion mass hierarchies and sizable CP-breaking effects. We investigate whether one can dynamically fix the moduli values in the vicinity of the fixed points in the context of Type IIB string theory. It is found that the string landscape prefers | δτ | ≃ 10 −
The syndrome of combined pulmonary fibrosis and emphysema (CPFE) has been characterized by severely impaired gas exchange and poor survival. However, the clinical features of patients with lung cancer plus CPFE have remained elusive. The present study performed a retrospective analysis to examine the clinical characteristics and outcome of surgically resected patients with lung cancer plus CPFE. Among 831 patients with primary lung cancer who underwent surgical resection, 23 patients (2.8%) were
A bstract We apply deep-learning techniques to the string landscape, in particular, SO(32) heterotic string theory on simply-connected Calabi-Yau threefolds with line bundles. It turns out that three-generation models cluster in particular islands specified by deep autoencoder networks and k-means++ clustering. Especially, we explore mutual relations between model parameters and the cluster with densest three-generation models (called “3-generation island”). We find that the 3-generation island
We study moduli stabilization of the F-theory compactified on an elliptically fibered Calabi–Yau fourfold. Our setup is based on the mirror symmetry framework including brane deformations. The complex structure moduli dependence of the resulting 4D N=1 effective theory is determined by the associated fourfold period integrals. By turning on appropriate G-fluxes, we explicitly demonstrate that all the complex structure moduli fields can be stabilized around the large complex structure point of th
A bstract We discuss non-invertible symmetries in toroidal compactifications of higher dimensional Yang-Mills theory with magnetic fluxes, which can be regarded as an effective action of type IIB string theory with magnetized D-branes. Specifically, we derive fusion rules of discrete isometry operators, which are invariant under the ℤ N orbifold twist. It turns out that degenerate chiral zero-modes non-trivially transform under the non-invertible symmetries in the context of quantum mechanics. H
Stenting for airway stenosis/obstruction may improve prognosis in patients with lung or thyroid cancer, especially if patients with lung cancer undergo additional treatments after stenting, although airway stenting for patients with esophageal cancer was palliative. New treatment strategies may be necessary for patients with esophageal cancer after stenting to improve prognosis.
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