arXiv subjects

Chuying Wang

Publications and source records attributed to Chuying Wang.

9 recordsLinked to original sources

arXiv2026

Target-space fusion of classical topological defects

Classical fusion of sigma-model defects is commonly approached by combining their worldsheet actions and eliminating the intermediate fields. This procedure, however, does not systematically identify the resulting target-space defect or its possible branches. We address this problem by formulating fusion as a reduction of the target-space defect data. Local descent of the intrinsic two-form and global descent of the connection determine the admissible branches. For symmetry-preserving bi-branes in the $SU(2)$ WZW model and Hopf-fibre T-duality defects, the prescription reproduces the known biconjugacy-class branches and the finite family of fibre-shift defects. The appearance of several branches provides a classical manifestation of non-invertible fusion. We further use the framework to construct TsT and T-dual biconjugacy defects, including their global consistency conditions. It therefore provides a systematic method for computing classical fusion and constructing new defects from known ones.

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arXiv2026

Fibre Inflation Beyond BHP: Constraints and a BHP-Free Regime

We study a restricted fibre-dependent $\alpha'$-loop sector in Type IIB Large Volume Scenario fibre inflation beyond the conventional Berg-Haack-Pajer (BHP) parametrisation. Motivated by effective-field-theory corrections in K3-fibred Calabi--Yau orientifolds, we analyse BHP-complete, partially BHP-driven and BHP-free configurations. For BHP-driven cases, the additional corrections act as effective deformations of the standard fibre potential and are bounded at the percent level relative to the corresponding BHP structures, with logarithmic terms typically more restricted due to their effects on the slope and curvature. At the effective-field-theory level, we identify a BHP-free fibre-inflation regime, referred to as $\alpha'$-loop inflation, in which the conventional KK- and winding-type BHP channels vanish while the generalized loop sector stabilises the fibre modulus and supports slow-roll inflation. This regime exhibits a characteristic hierarchy between fibre-dependent loop structures controlled by the large-volume suppression and satisfies CMB, K\"ahler-cone, large-volume and heavy-modulus constraints. Our results show that fibre inflation is sensitive to the orientifold and brane configurations, and that corrections beyond the BHP ansatz can generate new controlled inflationary regimes.

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arXiv2026

The Art of Networking: Networks of Trivalent 10d Heterotic Junctions

We initiate the study of networks of 10d string theories connected by junctions implied by the cobordism conjecture. Focusing on the recently constructed junction of the three 10d non-tachyonic heterotic theories, we generalize its $(0, 1)$ heterotic worldsheet description to construct arbitrary networks. For one-dimensional networks, we formulate their topology in terms of graph theory and provide a simple worldsheet realization for general graphs. We then extend our analysis to higher-dimensional networks, describing e.g. nucleation in a theory of bubbles of pairs of other theories. We also discuss compact configurations, which define a novel class of compactifications in which different sectors propagate on different compact spaces, in a way reminiscent of compactifications on quantum geometries like $S^1 \vee S^1$.

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arXiv2026

Heterotic Ouroboros

M-theory on ${\mathbf{S}}^1\vee{\mathbf{S}}^1$ has recently been proposed to yield, via quotients, ten-dimensional non-supersymmetric string theories. We revisit the construction that leads to the heterotic theories, finding a consistent set of rules that reproduces the light spectra and gauge groups, including indications of their global structure. Our approach uses the gauge enhancement mechanism of type I' string theory, applied to a setting in which the type I' interval is curled onto itself, with its two boundaries separated by a branch cut. Using these tools, we reproduce the ten-dimensional heterotic theories and provide some evidence for junctions among them.

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arXiv2026

Ho\v{r}ava-Witten theory on ${\mathbf{S}}^1\vee{\mathbf{S}}^1$ as type 0 orientifold

We investigate dualities between ${\mathbf{Z}}_2$ quotients of recently proposed compactifications of M-theory on `quantum geometries' of the form ${\mathbf{S}}^1\vee{\mathbf{S}}^1$ and 10d orientifolds of type 0A and 0B string theories. In particular, we relate the Ho\v{r}ava-Witten theory on ${\mathbf{S}}^1\vee{\mathbf{S}}^1$ to a 0B orientifold with gauge group $SO(16)^4$. The resulting dictionary provides a geometric explanation for characteristic features of the 0B orientifold, such as the doubling of the gauge group, while the perturbative spectrum of the 0B orientifold indicates the emergence of novel M-theoretic degrees of freedom associated with the junction point. The 0B orientifold further reveals the existence of two variants of the theory on ${\mathbf{S}}^1\vee{\mathbf{S}}^1$, corresponding to equal vs opposite (i.e., standard vs Fabinger-Ho\v{r}ava) orientations of the $E_8$ walls. We also analyze additional 0A and 0B orientifolds whose open string sectors do not arise from higher-dimensional gauge fields in M-theory and whose microscopic interpretation remains an open problem.

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arXiv2026

What IIB looks IIA string: String Cobordisms via Non-Compact CFTs

The Swampland Cobordism Conjecture predicts the existence of end-of-the-world branes for every consistent Quantum Gravity theory, and domain walls connecting the Landscape. A perturbative string worldsheet description of these objects is only expected to exist when certain worldsheet invariants are vanishing or coincide across the domain wall. In this paper, we observe that many of these worldsheet obstructions can be evaded by allowing non-compact string worldsheets as part of the bordism. Using these ideas, we provide a worldsheet QFT (flowing to a critical CFT under RG flow) that connects the worldsheets of 0A and 0B string theory, as well as those of IIA and IIB string theories. The non-compact character of these interpolations means that the description of the actual domain walls develop strongly coupled regions described by a linear dilaton background, where the worldsheet description breaks down. As a result, the IIA/IIB domain wall requires a strongly coupled region, in agreement with effective field theory considerations. Our constructions are heavily inspired by supercritical string theory, but are logically independent from it. We also analyze the fate of IIA/IIB NS5 branes as they cross the domain wall between these two theories.

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arXiv2025

Relative Quantum Gravity: Localized Gravity and the Swampland

We perform a systematic study of the applicability of swampland constraints to theories of localized gravity. We find that these gravity theories can violate swampland constraints, but can be reconciled with them when coupled to a higher-dimensional gravity theory. They realize what we call $\textit{relative quantum gravity}$: to become consistent at the quantum level, these gravity theories must be defined as $\textit{relative}$ to a host higher-dimensional gravity theory. We show that these theories can admit global symmetries, even anomalous ones; they can violate the cobordism, completeness, weak gravity, and distance conjectures; they may admit stable non-supersymmetric AdS vacua, or dS vacua. All swampland constraints are however satisfied when these gravity theories are regarded as relative and completed by coupling them to a higher-dimensional one. We discuss these properties in $d$-dimensional gravity theories localized on Karch-Randall End of the World (ETW) boundaries of AdS$_{d+1}$ spacetime. For AdS$_d$ ETW branes we use the formalism of double holography to describe the appearance of the species scale and the emergence of gauge dynamics from the quantum backreaction of CFT$_d$ modes. We also study microscopically the swampland constraints in localized gravity in explicit string theory models. Concretely, we exploit the 10d supergravity solutions describing AdS$_4$ ETW branes for AdS$_5\times\mathbf{S}^5$, holographically dual to semi-infinite D3-branes ending on NS5- and D5-brane configurations, realizing 4d $\mathcal{N}=4$ $SU(N)$ on half-space coupled to a 3d Gaiotto-Witten superconformal boundary CFT$_3$.

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arXiv2024

End of the World Boundaries for Chiral Quantum Gravity Theories

We describe the construction of large classes of explicit string theory backgrounds corresponding to 6d and 4d chiral theories with end of the world boundaries, and describe the strong coupling phenomena involved in gapping the chiral (but non-anomalous) sets of fields, such as strongly coupled phase transitions or symmetric mass generation. One class of 6d constructions is closely related to chirality changing phase transitions, such as those turning heterotic NS5-branes into gauge instantons, in flat space or orbifold singularities. A class of 4d models exploits systems of IIB D3-branes at toric CY3 singularities with an extra $\mathbf{Z}_2$ involution related to $G_2$ holonomy manifolds in the type IIB picture and its IIA mirror, which we explicitly describe in terms of dimer diagrams.

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arXiv2023

Dynamical Cobordism Conjecture: Solutions for End-of-the-World Branes

We analyze finite size solutions for a generalized $D$-dimensional Dudas-Mourad (DM) model featuring dynamical cobordism with neutral and charged end-of-the-world (ETW) defect branes. Confirming a dynamical version of the Cobordism Conjecture, we explicitly construct non-isotropic solutions for the latter codimension one branes and show the appearance of a lower bound $δ\ge 2\sqrt{(D-1)/(D-2)}$ for the critical exponent in the scaling behavior of the distance and the curvature close to the wall. This allows us to make a connection to the (sharpened) Swampland Distance Conjecture and the (Anti-) de Sitter Distance Conjecture. Moreover, BPS orientifold planes appear as special cases in our analysis and the whole picture is consistent with dimensional reduction from ten to $D$ dimensions. An analogous analysis is performed for a generalized Blumenhagen-Font (BF) model featuring neutral codimension two ETW-branes where the same lower bound for the scaling parameter $δ$ arises.

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