The candidate spectrum
The wave field \(\Psi_\infty\) on the infinite-dimensional manifold \(M_\infty\) admits candidate resonances at every pair \((n, d)\) where \(d\) is one of the six sector dimensions \(\{2, 3, 4, 5, 6, 10\}\) and \(n\) is any positive integer. Each such pair carries an associated frequency, sector mode function, and mass given by \(S(n,d) \times m_{\text{scale},d}\). The full lattice of candidates is essentially infinite.
Yet we observe exactly fifteen particles. A single geometric condition narrows the lattice down: the mode-sector pair \((n, d)\) must be a member of \(\Sigma_{\text{pairs}}\) — the closed set produced by the generation tower from the two seeds. Membership requires both the correct mode index and the correct sector; stability is a property of the pair, not of the mode index alone.
The co-fixed-point condition
A mode index n is a co-fixed-point of the sector comb filtration generated by seeds \(n_d=1\), \(n_u=3\), and composite \(n_s=4\) if the hockey-stick recursion \(S(n+1, d) = S(n, d) + S(n, d{-}1)\) closes at n — meaning n participates in one of the generation laws or is a simplex image of the seed. The sector d is fixed independently by the Hopf-chain structure that assigns each particle family to its sector. The pair \((n, d)\) is a stable particle exactly when it is a tower output.
This is a purely algebraic condition applied uniformly across every sector from the same composite \(n_s = 4\) and seed pair \(\{n_d=1,\, n_u=3\}\). The same filtration that selects the electron — a \(d=6\) \(\mathbb{CP}^3\) sector excitation of \(\Psi_\infty\), a genuine 6D object inhabiting six macroscopic spatial dimensions, whose 3D appearance is what a \(d=3\) observer measures — in \(d=6\) also selects the strange quark mode in \(d=3\) and the second neutrino mode in \(d=5\). Cross-sector uniformity is a consequence of coordinate nesting: all sectors share the same underlying \(M_\infty\), so the same algebraic filter applies throughout.
Modes for which the recursion does not close are not stable resonances of \(M_\infty\). They exist as eigenvalues of the Dirac operator, but two mechanisms make them unstable: modes at odd levels are l-parity disconnected from the seeds — no power of the sector kernel can reach them — and modes at even levels dephase permanently in the infinite-dimensional coupled system. Either way, they do not persist as particles.
The co-fixed-point condition is a structural postulate of IDWT, supported by the fact that it selects exactly the observed spectrum. Its full derivation from the IDWT equations of motion — why non-co-fixed-point modes are dynamically unstable — is an open item.
The selected spectrum: exactly 15
The members of \(\Sigma_{\text{pairs}}\) constitute the entire stable particle spectrum. The exhaustive result (verified computationally for \(n \leq 200\) across all six sectors) is:
| Particle | Sector | n | Co-fixed-point |
|---|---|---|---|
| \(\gamma\), W, Z, H | \(d=2\) | 0, 76, 81, 95 | ✓ |
| d quark, s quark | \(d=3\) | 1, 4 | ✓ |
| b quark | \(d=3\) | beat \(k_0=16\) | ✓ (quartic bifurcation) |
| u, c, t quarks | \(d=4\) | 3, 20, 72 | ✓ |
| \(\nu_1, \nu_2, \nu_3\) | \(d=5\) | 10, 15, 22 | ✓ |
| e, \(\mu\) | \(d=6\) | 13, 35 | ✓ |
| \(\tau\) | \(d=10\) | 23 | ✓ |
No mode-sector pair beyond these is a co-fixed-point. The spectrum is closed. There are no additional stable particles waiting to be discovered — not because the spectrum is truncated by an assumption, but because no further (n,d) pair is a tower output. Any new particle would require either a new sector (excluded by the sector set theorem T3) or a new co-fixed-point (exhaustively excluded).
What the unselected modes are
The vast majority of (n, d) pairs are not co-fixed-points. This does not mean they are absent from nature: every such pair exists as a resonance of \(\Psi_\infty\). It simply does not persist as a stable particle. The \(d=3\) modes at \(n=2\) and \(n=3\), for example, sit between the down and strange quarks (≈18.8 and 47 MeV); they are not co-fixed-points, so they appear at most as broad short-lived colour-triplet excitations, never as stable states.
The unselected modes include: all mode indices between the observed ones that fail to be tower outputs; and all modes in sectors \(d \geq 11\), which fall below the Jacobi coupling threshold and cannot form stable particles (Gegenbauer threshold theorem T5). What we call "the particle spectrum" is the stable subset of a far larger mathematical structure — fixed entirely by the three integer seeds \(\{n_d=1,\, n_u=3,\, n_{\rm top}=72\}\) (composite \(n_s = 4\)) and the geometry of \(M_\infty\).
See also: The Simplex Number · Three Generations · Why \(n_s = 4\) · The Six Sectors