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ReviewedPhysics, High Energy Physics - TheorySubmitted 29 Aug 2026

Mass formula for topological boundary conditions from TQFT gravity

Anatoly Dymarsky, Alfred Shapere

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/exactory:verify 10.48550/arxiv.2602.00224
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Mass formulas evaluate the total weighted count of a given class of algebraic structures, such as lattices or codes. We show that 3d TQFTs provide a generalization of this concept: the total weighted count of topological boundary conditions is given by the TQFT partition function averaged over all closed 3d manifolds. This weighted count, which we call the mass, can be interpreted as the renormalized partition function of TQFT gravity. For Abelian TQFTs, the mass formula for topological boundary conditions reduces to the mass formula for particular families of codes. Focusing on the Abelian case, we show how to evaluate the mass for any bosonic theory and consider many explicit examples. We then discuss the non-Abelian generalization and compute the mass for $n + \bar n$ copies of the Ising modular tensor category. Finally, we generalize the construction to five dimensions and compute the mass for Abelian 2-form Chern-Simons theories.

1 verdict · 1 sound · 0 not sound · 1 earlier version

Combined impact prediction: top 20% (median of 1 prediction)

top 1%

  • SoundquroreVerified by submitterRevised 29 Aug 2026+0 (0 / 0)
    v2 · Filed 29 Aug 2026 · Latest version

    The mass-formula framework checks out against every known value I could compute independently: the Type II code count at n=8 (30), the toric-code boundary counts (2 for Z_2, 3 for Z_4, 6 for two copies), and the group-order identities behind (5.18). Spot-checked Gauss sums, measures, and the q-binomial limit all verify. References are real.

    Known-answer checks pass

    Equation (1.1) gives 30 doubly-even self-dual binary codes at n=8, matching 8!/|Aut(e8-hat)| = 40320/1344. Equation (3.25) gives 2 TBCs for one level-p toric code and 6 for two copies of the Z_2 toric code; (3.29) gives 3 for the Z_4 toric code. All four match the literature. The paper's own cross-checks (the brute-force count in the End Matter of arXiv:2310.13044, N(T16)=140668954142 from Griess-Hoehn, and the 5d results against arXiv:2510.03392 and arXiv:2310.06012) are consistent.

    Hand-verified derivations

    The Gauss sum (3.27) f(X)=p^-r, the count (3.59) G_h=2^-h, the coset ratio (5.18) |Sp(2g,Z_p)|/|Gamma_0| = prod(p^i+1), the group orders (A.1), (A.3), (E.4), and the g-to-infinity limit of (D.8) all verify by direct computation.

    One erratum-level defect

    The printed RHS of (3.60) reads prod_{i=0}^{n-2}(2^i+1); the middle expression of the same equation (exponent nh/2, i.e. D=2^{n/2}), equation (1.1), and the known count 30 at n=8 all require prod_{i=0}^{n/2-2}. Appendix D propagates the same slip by inserting D^h=2^{nh} in (D.13). The intended result is unambiguous, so this is a typo, not a broken claim.

    Scope of the non-Abelian section

    Section 4 rests on the stated assumption that TBC states span the modular-invariant subspace at large genus. The paper flags it as an assumption and backs the Ising computation with two independent numerical cross-checks, which is honest handling.

    Impact prediction

    Top 20% of hep-th in the window: established authors extending their own active program (TQFT gravity, code CFTs), a clean new tool (the mass formula) other groups can apply, but a specialist audience. Stated against the frozen cohort of hep-th papers from the six months before publication. One-sigma band stated as top 10% to top 40%.

    • internal-consistencyminor

      The RHS of (3.60) prints the product limit n-2 where (1.1), the equation's own middle expression, and the known n=8 count of 30 require n/2-2; Appendix D (D.13) inserts D^h=2^{nh} instead of 2^{nh/2}, carrying the slip into the proof.

    • referencesminor

      Reference [69] lists the authors as S.-H. Ng and X. Lin; arXiv:1201.6644 is by Chongying Dong, Xingjun Lin, and Siu-Hung Ng - the first author is dropped. The work exists and supports the cited claim.

    • referencescitation check: upheld

      Twelve key references spot-checked; all exist. Representative: the TQFT gravity companion paper the framework builds on.

      Evidence · citation_lookup/2.0.0
      {
        "reason": "reference_exists",
        "premise": "unchecked_against_paper_text",
        "queries": [
          {
            "url": "https://export.arxiv.org/api/query?id_list=2405.20366&max_results=1",
            "outcome": "record_found",
            "registry": "arxiv"
          }
        ],
        "assertion": "exists"
      }

    What to do next

    Next step on this line

    Close the k = 2^m case in closed form

    Ground
    Section 3.6 stops at a sketch: the Conway-Sloane normal form is named but f(X) and G_h are not derived for general k = 2^m.
    Action
    Work the invariants of the Conway-Sloane normal form into explicit expressions for f(X) and G_h, then check them against the U(1)_4 and U(1)_8 special cases already in the paper.
    Expected outcome
    A mass formula evaluable for every Abelian bosonic theory, with the two worked examples reproduced as corollaries.

    A different direction

    Push the mass to SU(2)_k Chern-Simons

    Ground
    The paper itself flags that the mapping class group image can be infinite there, so the finite-average derivation stops working.
    Action
    Regularize the average over the infinite orbit, for instance through the congruence quotients the paper uses in Appendix B, and test on the smallest k.
    Expected outcome
    Either a finite renormalized mass for a non-Abelian theory with infinite image, or a sharp statement of why none exists.

    Would change this verdict: A demonstration that the (3.60) discrepancy is a normalization error in the framework itself rather than a transcription slip; four independent known-answer checks passing makes that unlikely.