The paper constructs arbitrary networks of 10d non-tachyonic heterotic string theories via cobordism-implied junctions and gives worldsheet realizations for graphs, higher-dimensional networks, and compact configurations with sectors on different spaces.
Mixed citations
The Art of Branching: Cobordism Junctions of 10d String Theories
Mixed citation behavior. Most common role is background (60%).
7
Pith papers citing it
Background
60% of classified citations
abstract
We describe the explicit construction of configurations of several 10d string theories joining at a 9d junction, providing a dynamical realization of cobordisms between multiple 10d string theories, predicted by the Cobordism Conjecture. We provide the microscopic worldsheet description of the configuration in a generalization of the `going up and down the RG flow' interpolations recently used in the description of IIA/IIB domain wall. The interpolations involve additional degrees of freedom, which are gapped except at the branch point, at which the gap closes and triggers the branching transition. The extra degrees of freedom admit an interpretation in terms of additional dimensions in a supercritical string theory, which reduces to the 10d junction configuration upon closed tachyon condensation. Quantum corrections of the 2d worldsheet theory turn the junction into a strongly coupled lightlike core whose UV resolution lies beyond worldsheet techniques. We construct explicit examples of junctions of 10d heterotic string theories, type 0, and type II theories and orientifolds thereof. Our explicit examples include junctions of 10d chiral theories whose chiral fields flow between different branches. One particularly nice configuration is a 4-branch junction of the IIB theory, with type I, the non-supersymmetric $USp(32)$ theory and the $U(32)$ orientifold of 0B theory, thus assembling the four non-tachyonic descendants of type 0B theory.
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hep-th 7years
2026 7verdicts
UNVERDICTED 7representative citing papers
Sharpened Dynamical Cobordism ties the allowed range of critical exponent δ to theory structure ξ, flagging obstructions from non-trivial cobordism charges that require new degrees of freedom.
Hořava-Witten theory on S¹∨S¹ is dual to a type 0B orientifold with SO(16)^4 gauge group, explaining gauge group doubling via the geometry's junction and revealing two variants from E8 wall orientations.
Proposes a refinement of the Swampland Cobordism Conjecture for duality groups, arguing that diverging commutator widths necessitate infinitely many duality defects to realize monodromies in 9d supergravity bordisms.
A duality web is proposed in which Z2 quotients of M-theory on S1 vee S1 and F-theory on (S1 vee S1) x S1 map to 0A/0B orientifolds and non-supersymmetric E-type and D-type heterotic strings, providing evidence for existing dualities.
Worldsheet effects from wedge singularities plus D0-brane emergence reproduce the tree-level tachyon mass in type 0A strings within a specific scaling limit.
A consistent set of rules from M-theory on S¹ ∨ S¹ combined with type I' enhancements reproduces the light spectra, gauge groups, and global structure of ten-dimensional heterotic string theories, with indications of junctions between them.
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Bordisms between 9d type IIB supergravities and commutator widths of duality groups
Proposes a refinement of the Swampland Cobordism Conjecture for duality groups, arguing that diverging commutator widths necessitate infinitely many duality defects to realize monodromies in 9d supergravity bordisms.