河備　浩司 （カワビ　ヒロシ）

Kawabi, Hiroshi

写真a

所属（所属キャンパス）

経済学部 （日吉）

職名

教授
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  • Stochastic quantization associated with the exp (Φ) <inf>2</inf> -quantum field model driven by space-time white noise on the torus in the full L<sup>1</sup> -regime

    Hoshino M., Kawabi H., Kusuoka S.

    Probability Theory and Related Fields （Probability Theory and Related Fields）  185 （ 1-2 ） 391 - 447 2023年02月

    ISSN  01788051

    　概要を見る

    The present paper is a continuation of our previous work (Hoshino et al., J Evol Equ 21:339–375, 2021) on the stochastic quantization of the exp (Φ) 2-quantum field model on the two-dimensional torus. Making use of key properties of Gaussian multiplicative chaos and refining the method for singular SPDEs introduced in the previous work, we construct a unique time-global solution to the corresponding parabolic stochastic quantization equation in the full “L1-regime” |α|<8π of the charge parameter α. We also identify the solution with an infinite-dimensional diffusion process constructed by the Dirichlet form approach.

  • Central Limit Theorems for Non-Symmetric Random Walks on Nilpotent Covering Graphs: Part II

    Ishiwata S., Kawabi H., Namba R.

    Potential Analysis （Potential Analysis）  55 （ 1 ） 127 - 166 2021年06月

    ISSN  09262601

    　概要を見る

    In the present paper, as a continuation of our preceding paper (Ishiwata et al. 2018), we study another kind of central limit theorems (CLTs) for non-symmetric random walks on nilpotent covering graphs from a view point of discrete geometric analysis developed by Kotani and Sunada. We introduce a one-parameter family of random walks which interpolates between the original non-symmetric random walk and the symmetrized one. We first prove a semigroup CLT for the family of random walks by realizing the nilpotent covering graph into a nilpotent Lie group via discrete harmonic maps. The limiting diffusion semigroup is generated by the homogenized sub-Laplacian with a constant drift of the asymptotic direction on the nilpotent Lie group, which is equipped with the Albanese metric associated with the symmetrized random walk. We next prove a functional CLT (i.e., Donsker-type invariance principle) in a Hölder space over the nilpotent Lie group by combining the semigroup CLT, standard martingale techniques, and a novel pathwise argument inspired by rough path theory. Applying the corrector method, we finally extend these CLTs to the case where the realizations are not necessarily harmonic.

  • Stochastic quantization associated with the exp (Φ) <inf>2</inf> -quantum field model driven by space-time white noise on the torus

    Hoshino M., Kawabi H., Kusuoka S.

    Journal of Evolution Equations （Journal of Evolution Equations）  21 （ 1 ） 339 - 375 2021年03月

    ISSN  14243199

    　概要を見る

    We consider a quantum field model with exponential interactions on the two-dimensional torus, which is called the exp (Φ) 2-quantum field model or Høegh-Krohn’s model. In the present paper, we study the stochastic quantization of this model by singular stochastic partial differential equations, which is recently developed. By the method, we construct a unique time-global solution and the invariant probability measure of the corresponding stochastic quantization equation and identify it with an infinite-dimensional diffusion process, which has been constructed by the Dirichlet form approach.

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競争的研究費の研究課題 【 表示 ／ 非表示 】

  • 幾何解析の視点を融合した無限次元空間上の確率解析の新展開

    2023年04月
    -
    2026年03月

    河備 浩司, 基盤研究(C), 補助金,  研究代表者

  • 幾何学的視点を融合した無限次元空間上の確率解析の研究

    2020年04月
    -
    2023年03月

    文部科学省・日本学術振興会, 科学研究費助成事業, 河備 浩司, 基盤研究(C), 補助金,  研究代表者

  • 無限次元空間上の微分作用素の確率解析的研究

    2017年04月
    -
    2020年03月

    文部科学省・日本学術振興会, 科学研究費助成事業, 河備　浩司, 基盤研究（Ｃ）, 補助金,  研究代表者

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担当授業科目 【 表示 ／ 非表示 】

  • 経済数学

    2023年度

  • 確率論入門Ⅱ

    2023年度

  • 確率論入門Ⅰ

    2023年度

  • 微分積分入門

    2023年度

  • 微分積分

    2023年度

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