Hamiltonian gauge theory with corners: constraint reduction and flux superselection
Bibliographic record
Abstract
We study gauge theories on spacetime manifolds with a codimension-$1$ submanifold with boundary. We characterise the reduced phase space of the theory whenever it is described by a local momentum map for the action of the gauge group $\mathcal{G}$, by means of Fréchet reduction by stages. The momentum map decomposes into a bulk term called constraint map, defining a coisotropic constraint set, and a boundary term called flux map. In the first stage, constraint reduction, the constraint set is the zero of a momentum map for a normal subgroup $\mathcal{G}_\circ\subset\mathcal{G}$, called constraint gauge group. In the second stage, flux superselection, the flux map is the momentum map for the residual action of the flux gauge group $\underline{\mathcal{G}}\doteq\mathcal{G}/\mathcal{G}_\circ$, which also controls equivariance. The reduced phase space of the theory, when smooth, is then only a partial Poisson manifold $\underline{\underline{\mathcal{C}}}\simeq \underline{\mathcal{C}}/\underline{\mathcal{G}}$. Its symplectic leaves are called \emph{flux superselection sectors}, for they provide a classical analogue of, and a road map to, the phenomenon of quantum superselection. To corners, we further assign a symplectic Lie algebroid over a Poisson manifold, $\mathsf{A}_{\partial} \to \mathcal{P}_{\partial}$, and show how on-shell configurations $\mathcal{C}_{\partial}\subset\mathcal{P}_{\partial}$ are also Poisson. Both $\mathcal{C}_{\partial}$ and $\underline{\underline{\mathcal{C}}}$ fibrate over a common space of superselections, labeling the Casimirs of both Poisson structures. We showcase the formalism by explicitly working out the first and second stage reductions for a broad class of Yang--Mills theories, where $\underline{\underline{\mathcal{C}}}$ is found to be a Weinstein space, and discuss further applications to topological theories.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.004 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.012 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".