arXiv subjects

Masashi Kawahira

Publications and source records attributed to Masashi Kawahira.

6 recordsLinked to original sources

arXiv2026

Anomalies and discrete torsion in Type II and Type I worldsheet theories

We provide a comprehensive study of anomalies and discrete torsion in the worldsheet theories of Type II and Type I string theories on a general ten-dimensional target space. In the modern understanding, the anomaly of a worldsheet theory is characterized by an invertible field theory in three dimensions, and invertible field theories are classified by the Anderson dual of a suitable bordism theory. To study the anomaly cancellation condition, we employ the explicit model of the Anderson dual constructed by Yamashita and Yonekura. We find that, for both Type II and Type I string theories, the anomaly of the worldsheet theory is cancelled if and only if the target space is orientable and admits a spin structure. We also determine the discrete torsion and clarify its physical meaning. It includes the distinctions between Type IIA and Type IIB string theories and between ordinary Type I and Sugimoto string theories.

hep-th↗

arXiv2026

Deconfinement-Higgs continuity in ${\rm SU(2)}$ adjoint Higgs model at finite temperature

We study the finite-temperature phase structure of the four-dimensional ${\rm SU}(2)$ adjoint Higgs model, focusing on a possible \textit{deconfinement-Higgs continuity}: the conjecture that the high-temperature deconfined phase of Yang-Mills theory and the finite-temperature Higgs phase form a single thermodynamic phase. We first perform a global-symmetry analysis, showing that the Higgs and deconfined regimes are expected to share the same symmetry pattern, which is distinct from that of the confined phase. This suggests deconfinement-Higgs continuity, but does not exclude the possibility that the deconfined phase and the Higgs phase are separated by a phase transition not associated with the global symmetries. We then perform a deformation analysis, which yields an explicit continuous path between the ``deconfined symmetric'' and ``deconfined Higgs'' regions in a reduced three-dimensional lattice model. These results indicate that the Higgs and deconfined regimes can be continuously connected, while the confined phase remains distinct.

hep-th↗

arXiv2026

7-branes and $Γ_0(2)$ Duality in Type 0B String Theory

We investigate 7-branes in type 0B string theory, motivated by the recent proposal of Baykara, Dudas, and Vafa, which connects type 0B string theory with M-theory. On the $Q$-symmetric branch, the self-duality group of type 0B string theory is $Γ_0(2)$, whose Abelianization is $\mathbb{Z}\times\mathbb{Z}_4$. This implies the existence of two independent 7-brane charges. We construct explicit charge operators in terms of modular forms and identify the corresponding charged objects in gravity solutions. One is the ordinary D7-brane, while the other is a 7-brane carrying a nontrivial $\mathbb{Z}_4$ charge. We further construct a compact background consisting of eight such $\mathbb{Z}_4$ 7-branes using a restricted Weierstrass model. Remarkably, in this background the axio-dilaton is fixed to the constant value $τ=(1+\mathsf{i})/2$, which coincides with the unstable de Sitter critical point proposed in the M-theory description of type 0B string theory. We also analyze fluctuations in the $Q$-odd sector and find that, although the corresponding equations of motion are globally well-defined in this background, the closed string tachyon remains unstable. Our results provide a concrete realization of new 7-branes in type 0B string theory and clarify their relation to its strong-coupling structure.

hep-th↗

arXiv2026

Emergent higher-form symmetry from type IIB superstring theory

We investigate a higher-form symmetry in type IIB superstring theory, which possesses an ${\rm SL}(2,\mathbb{Z})$ symmetry. From the point of view of the low-energy effective field theory, the ${\rm SL}(2,\mathbb{Z})$ symmetry is treated as a gauge symmetry. Hence, an $8$-form global symmetry $\mathbb{Z}_{12}^{[8]}$ emerges as a quantum symmetry. In this paper, we present an explicit construction of the topological operator associated with the $\mathbb{Z}_{12}^{[8]}$ symmetry. In this construction, the discriminant $Δ(τ)$ plays a central role. As a result, it becomes manifest that $\mathbb{Z}_{12}^{[8]}$ is the solitonic symmetry of $7$-branes. Furthermore, taking into account the extensions of the duality group, we also discuss what global symmetries emerge when considering not ${\rm SL}(2,\mathbb{Z})$ but ${\rm Mp}(2,\mathbb{Z})$, ${\rm GL}(2,\mathbb{Z})$, and ${\rm Pin}^+({\rm GL}(2,\mathbb{Z}))={\rm GL}^+(2,\mathbb{Z})$.

hep-th↗

arXiv2025

States and IR divergences in factorization algebras

In field theory, one can consider a variety of states. Within the framework of factorization algebras, one typically works with the natural augmentation state $\langle-\rangle_{\rm aug}$. In physics, however, other states arise naturally, such as the compactification state $\langle-\rangle_{\rm cptf}$ or the Schwartz state $\langle-\rangle_{\rm Sch}$, defined by imposing Schwartz boundary conditions. At first sight, the relation among these three states is not obvious. This paper gives a definition of the compactification state in factorization algebras and provides a method for handling infrared divergences in the massless theory. We then prove that the three states are equivalent in both the massive and massless cases.

hep-th↗

arXiv2024

A concrete construction of a topological operator in factorization algebras

Factorization algebras play a central role in the formulation of quantum field theories given by Kevin Costello and his collaborators. In this paper, we propose a concrete construction of a topological operator in their formulation. We focus on a shift symmetry of a one-dimensional massless scalar theory. And we give some discussions of $\mathbb{Z}$-gauging of it, i.e., compact scalar theory and its $θ$-vacuum.

hep-th↗