Rational Analytic Syntomification in p-adic Cohomology
- Rational analytic syntomification is a p-adic geometric construction that replaces traditional analytic objects with stacks encoding prismatic, Nygaard-filtered, and syntomic data.
- It employs pushouts and coequalizers to glue de Rham and Hodge–Tate realizations, enabling the recovery of syntomic complexes and related cohomological structures.
- The framework bridges p-adic geometry with crystalline local systems and admissible filtered F‑isocrystals, providing insights into duality, Chern class formalism, and vector bundle correspondences.
Rational analytic syntomification is a -adic geometric construction in which a rigid-analytic or formal object is replaced by a stack whose quasicoherent or perfect complexes encode syntomic, de Rham, Hodge–Tate, Hyodo–Kato, and étale data in a single framework. For a partially proper rigid-analytic variety over , the rational analytic syntomification is built from the rational analytic prismatisation $X^\Prism$ and its Nygaard-filtered refinement , and rational analytic syntomic cohomology is defined by
For a smooth -adic formal scheme , a closely related syntomic stack 0 is defined as a pushout of the Nygaard-filtered prismatization along de Rham and Hodge–Tate comparison maps (Hauck, 16 Apr 2026, Pentland, 19 Oct 2025).
1. Definition and terminological scope
Two explicit constructions underlie the current meaning of syntomification. In the formal 1-adic setting, the syntomic stack 2 is defined as the pushout of 3 along two copies of 4, via the maps 5 and 6; equivalently,
7
In the rigid-analytic setting, the rational analytic syntomification is defined as the coequalizer
8
where the two arrows are the embeddings 9 (Pentland, 19 Oct 2025, Hauck, 16 Apr 2026).
| Setting | Basic construction | Structural role |
|---|---|---|
| Smooth 0-adic formal scheme 1 | Pushout defining 2 from 3 and 4 | Geometrizes syntomic cohomology and 5-gauges |
| Partially proper rigid-analytic 6 | Coequalizer 7 | Produces rational analytic syntomic cohomology |
In the rigid-analytic theory, “rational” refers to working after inverting 8, with coefficients in 9, and “analytic” refers to rigid-analytic, Berkovich, and Gelfand-stack geometry. In the formal theory, syntomification is the stack-theoretic operation that adds syntomic structure to prismatic and Nygaard-filtered data, so that derived global sections recover syntomic complexes (Hauck, 16 Apr 2026, Pentland, 19 Oct 2025).
2. Prismatisation, Nygaardification, and the gluing mechanism
The rigid-analytic construction begins from the rational analytic prismatisation 0. For a totally disconnected nilperfectoid Gelfand ring 1, one has a derived Berkovich space 2 with Frobenius
3
a map 4, and a radius map
5
A degree-6 Cartier divisor 7 determines the prismatisation of the base, and 8 is obtained by taking morphisms 9. The de Rham stack satisfies
0
and 1 inherits both a radius map 2 and a Frobenius 3 with 4 (Hauck, 16 Apr 2026).
Nygaardification introduces filtered structure. The base 5 is defined by a pullback involving 6, the overconvergent closed unit disk, and its de Rham stack. For 7, the Nygaardification 8 is defined using a 9-nilpotent thickening $X^\Prism$0 of the degree-$X^\Prism$1 divisor $X^\Prism$2, and
$X^\Prism$3
There is a natural projection
$X^\Prism$4
and two distinguished embeddings of $X^\Prism$5 into $X^\Prism$6.
The first embedding is the de Rham copy: $X^\Prism$7 arising from the locus $X^\Prism$8, where $X^\Prism$9. The second embedding is the Hodge–Tate copy: 0 arising from the locus 1, and it satisfies
2
Away from the de Rham and Hodge–Tate loci, the Nygaardification is explicitly a cylinder: 3 This identifies 4 with the endpoint 5 and 6 with the Frobenius-twisted endpoint 7. The syntomification 8 is then the stack obtained by identifying these two copies of 9 inside 0 (Hauck, 16 Apr 2026).
The formal-stack construction exhibits the same pattern in a different language. There, 1 is the pushout of 2 along two maps from 3, and the resulting exact triangle
4
recovers syntomic complexes such as 5 (Pentland, 19 Oct 2025).
3. Cohomology, duality, and Chern classes
The basic coefficient object on 6 is the Breuil–Kisin twist 7. On 8 it refines the pullback of the corresponding line bundle from 9, and its pullbacks along 0 and 1 agree, so 2 descends to 3. This yields rational analytic syntomic cohomology in weight 4: 5 More generally, for 6,
7
defines syntomic cohomology with coefficients in perfect analytic 8-gauges (Hauck, 16 Apr 2026).
A central structural theorem is the fiber-square description
9
valid for 0 a Berkovich smooth derived Berkovich space over 1. For the unit object 2, this recovers the usual syntomic comparison pattern between Hyodo–Kato and filtered de Rham realizations. A second fiber-square description relates syntomic, divisor, and Hodge–Tate stacks: 3 This underlies the truncated comparison
4
for the unit coefficient and, more generally, for vector bundle analytic 5-gauges with Hodge–Tate weights 6 (Hauck, 16 Apr 2026).
Rational analytic syntomic cohomology satisfies Poincaré duality. For the structural map
7
the dualizing complex is
8
If 9 is smooth proper of pure relative dimension 00, then
01
and for 02 smooth proper of dimension 03,
04
The shift 05 at the base is attributed to the extra topological dimension of the Nygaard interval direction (Hauck, 16 Apr 2026).
The theory also carries a strong first Chern class formalism: 06 compatible with functoriality, additivity, pullback, and tensor product. The projective bundle formula is realized by the isomorphism built from powers of 07 for 08 (Hauck, 16 Apr 2026).
4. Vector bundles, de Rham coefficients, and the Fargues–Fontaine curve
The coefficient theory of syntomification is controlled by the relative Fargues–Fontaine curve. If 09 is smooth partially proper over 10, then
11
where the right-hand side is the full subcategory of vector bundles on the relative Fargues–Fontaine curve 12 that are de Rham. Under this equivalence, de Rham 13-local systems on the pro-étale site embed fully faithfully into 14 (Hauck, 16 Apr 2026).
This description specializes cleanly at a point. For 15,
16
the category of 17-equivariant de Rham vector bundles on the Fargues–Fontaine curve. For de Rham representations 18,
19
and in particular
20
Thus vector bundles on 21 are not auxiliary coefficients but a geometric model for classical de Rham 22-adic Hodge-theoretic objects (Hauck, 16 Apr 2026).
The same perspective explains the role of the Hyodo–Kato stack
23
An object of 24 is simultaneously a Hyodo–Kato object on 25, a filtered de Rham object on 26, and a compatible object on 27. This places syntomification at the intersection of Frobenius, monodromy, filtration, and de Rham comparison data (Hauck, 16 Apr 2026).
5. Formal-scheme syntomification, crystalline local systems, and rationalization
For a smooth 28-adic formal scheme 29, syntomification is formulated in the language of 30-gauges. The heart 31 contains a reflexive subcategory 32, defined by the condition that the natural map
33
is an isomorphism. The étale realization functor is symmetric monoidal, respects duals, and induces an equivalence
34
where 35 is the rigid generic fiber and the target is the category of pro-étale crystalline 36-local systems. More generally, if 37, then every
38
is a crystalline 39-local system on 40 (Pentland, 19 Oct 2025).
Rationalization removes integral syntomic torsion. The kernel of
41
consists precisely of coherent 42-gauges killed by a power of 43. After inverting 44, one obtains
45
and the essential image of
46
is the full subcategory whose cohomology sheaves are crystalline 47-local systems. When 48 is smooth proper, there is a 49-exact symmetric monoidal equivalence
50
where the target consists of perfect complexes whose cohomology sheaves are admissible filtered 51-isocrystals (Pentland, 19 Oct 2025).
These results identify syntomification as a rational bridge between integral 52-gauge geometry and analytic crystalline local systems. The role of rationalization is explicit: it passes from lattices and syntomic torsion to isogeny categories and admissible filtered 53-isocrystals (Pentland, 19 Oct 2025).
6. Broader rational–analytic motifs and adjacent frameworks
Two adjacent literatures isolate structural themes that illuminate the phrase “rational analytic syntomification,” even though they are not themselves 54-adic syntomic theories.
For relative semi-abelian schemes over an affine complex curve 55, the study of analytic and rational sections develops a direct comparison between algebraic and analytic height formalisms. The same differential 56-form 57 gives the Néron–Tate height of a rational section,
58
and an analytic growth functional for a holomorphic section,
59
The theory proves, among other statements, that if 60, then 61 must be rational, and that transcendental holomorphic sections have Zariski closures with positive-dimensional stabilizer; for strictly transcendental sections, after finite base change, the closure is a translate of an abelian subscheme by a rational section (Corvaja et al., 2020).
For discrete analytic functions on the lattice 62, rationality is redefined because pointwise multiplication does not preserve discrete analyticity. The relevant product is the convolution product 63, rational discrete analytic functions are realized by
64
and discrete analytic Schur multipliers admit co-isometric realizations on de Branges–Rovnyak spaces. Rationality is equivalent to several finite-dimensional conditions, including the existence of a polynomial 65 such that 66 is polynomial and the finite-dimensionality of
67
These frameworks suggest a recurrent structural pattern. Analytic data are encoded by auxiliary geometric or operator-theoretic objects—cohomological stacks, kernels, or colligations—and rationality is detected by finite-dimensionality, bounded growth, or compatibility with a distinguished product. A plausible implication is that syntomification, in the narrow 68-adic sense of 69, belongs to a wider class of constructions in which one replaces a naive analytic object by a more structured carrier that simultaneously records analytic, algebraic, and realization-theoretic information (Corvaja et al., 2020, Alpay et al., 2021).
Within the 70-adic setting, that carrier is the syntomic stack itself. Its defining gluing identifies de Rham and Hodge–Tate incarnations of prismatised geometry; its line bundles produce rational analytic syntomic cohomology; its vector bundles recover de Rham bundles on the Fargues–Fontaine curve; and its rationalized perfect complexes recover crystalline local systems and admissible filtered 71-isocrystals (Hauck, 16 Apr 2026, Pentland, 19 Oct 2025).