Appendix D.1. Six-Dimensional Branch: Chiral Vortex, Stability, and a Nonminimal Confining No-Turn Completion
Reader checkpoint: map of the 6D branches.Four logically different six-dimensional constructions are kept separate below: the reference Einstein–Abelian–Higgs vortex; the smooth nonminimal no-turn Einstein–sigma/confining branch; the finite-radius interface fallback; and higher-curvature local-response candidates. Results proved in one branch are not silently transferred to another. The 6D analysis is prospective ultraviolet structure and is not used to prove the 4D route identity or the 5D spectral reconstruction.
Status and role of the six-dimensional analysis.The six-dimensional construction is not used to establish the principal four- and five-dimensional results. Its purpose is to test whether the four-dimensional route mechanism and the five-dimensional effective spectral representation can coexist with a smooth higher-dimensional origin of chirality and localization. Within the displayed local two-derivative nonminimal branch, the no-turn background and the complete axisymmetric scalar/radion nonnegativity theorem are established. In the regular dipole sector, the former fixed-metric value is removed as a physical tachyon because its eigenfunction lies in the scalar-clock gauge image and has exactly zero Schur curvature after stationary metric completion. Full six-dimensional stability is nevertheless not claimed. The constraint-reduced physical dipole operator , its threshold number , higher angular harmonics, interface-localized modes, microscopic confinement, admissible fermion/Yukawa representations, anomaly inflow, and route matching remain open. The 6D branch is therefore a prospective ultraviolet extension, not an input to the main 4D/5D conclusions.
Extra dimensions are not needed for the existence of the four-dimensional rank-one sign source, but six dimensions can play a different role: they may provide a literal smooth ultraviolet completion in which vectorlike higher-dimensional parents generate exactly chiral four-dimensional preons, while gravity and spectator gauge modes are localized without hard branes. The construction considered here is no longer based on a prescribed string-cigar metric. A self-consistent backreacted Einstein–Abelian–Higgs vortex satisfies the direct-product Dai–Freed consistency test; a source-free top form converts homogeneous regularity selection into the choice of an integration constant; the transverse-traceless gravitational and spectator-gauge sectors have nonnegative Rayleigh quotients; the coupled vortex-vector operator factorizes and has no tachyon; and independent graviphoton zero modes and a localized massless scalar modulus are absent. The full gauge-invariant scalar analysis further separates a stable, threshold-local transverse metric–gauge channel from a background “sausage” sector that is generically rigid under regular-core and finite-volume boundary conditions. In the natural nonminimal no-turn branch, an exact positive-square construction additionally factorizes the complete -independent coupled scalar/radion Hamiltonian and excludes normalizable . A separate finite-radius alternative closes the classical Israel–Maxwell–scalar junction but introduces an interface fluctuation problem that remains open. Thus the remaining problem is considerably narrower than the statement that an entire massive scalar Green operator is unknown, but broader than bulk stability alone.
Appendix D.13.1. Earlier Six-Dimensional Obstructions and the Smooth Alternative Branch
Several earlier no-go results remain valid within their respective assumptions:
- 1.
a chiral six-dimensional Weyl lift using only the published matter content has an irreducible local anomaly obstruction;
- 2.
an ordinary two-reflection orbifold does not simultaneously give the desired four-dimensional chirality and the required route structure;
- 3.
the tested full-mirror/free- construction has a nontrivial global torsion obstruction;
- 4.
a finite hard rectangle permits independent face and corner gauge-kinetic counterterms;
- 5.
a minimal chiral one-tensor construction does not satisfy the required irreducible quartic condition;
- 6.
a naively prescribed separable conformal warp contains geometric defects and is not a self-consistent Einstein–Abelian–Higgs solution.
The smooth branch changes precisely these assumptions. It uses one vectorlike six-dimensional Dirac parent for each published four-dimensional preon multiplet, a smooth unit-winding codimension-two defect, a consistent
charge assignment, standard bulk Yang–Mills kinetic terms, and a self-consistent gravitating vortex. String-cigar backgrounds and gauge localization provide useful precedents for smooth codimension-two localization [
19,
20], but here the geometry is determined by the coupled Einstein–Abelian–Higgs equations rather than imposed analytically.
Appendix D.13.2. Consistent Normalization of the Spin c Charges
For each published four-dimensional multiplet
, introduce a vectorlike six-dimensional Dirac field whose six-dimensional chiral components are
Let
denote the auxiliary defect connection and
the complex vortex scalar. Both are singlets under
Use the integer normalization
The chirality projectors are
and the vortex Yukawa coupling is
Under a
transformation of angle
,
At
, every fermion acquires
while the charge-two scalar is unchanged. Identifying this central element with fermion parity leads naturally to
Accordingly, is most naturally interpreted as the connection entering the structure rather than as an unconstrained additional low-energy Abelian gauge factor.
Appendix D.13.3. Local Anomaly Polynomial and the Dai–Freed Criterion for the Direct-Product Group
For a vectorlike six-dimensional Dirac parent in representation
R, the anomaly polynomial is the difference of the two six-dimensional Weyl contributions,
where
is the
Abelian curvature,
the non-Abelian curvature,
the Chern character in representation
R, and
the gravitational
genus. Terms even in
cancel between the two chiralities. For a product of special-unitary factors, the potentially relevant mixed term is proportional to
, whose coefficient is exactly the ordinary four-dimensional cubic anomaly sum. For the published preon spectrum,
while the perturbative cubic trace vanishes for
and
. Hence
For the direct-product global group
G, the corresponding global-anomaly check may be formulated through the Atiyah–Hirzebruch spectral sequence
The relevant odd
coefficient groups vanish in the required low degrees, while the integral homology of products of
is supported in even degrees. There are therefore no nonzero
entries with
, giving
Under the stated direct-product assumption, both the local anomaly polynomial and the torsion global-anomaly test therefore vanish. If the true global gauge group is later quotiented by common center elements or tied nontrivially to spin structure, the bordism calculation must be repeated for that actual global form.
Appendix D.13.4. Self-Consistent Einstein–Abelian–Higgs System
The central change relative to prescribed cigar geometries is to solve for the warp factors together with the defect fields. The analysis uses the standard six-dimensional gravitating Abelian-vortex system [
21],
Here
is the six-dimensional Planck scale,
R is the six-dimensional Ricci scalar,
is the bulk cosmological constant,
is the vortex Abelian field strength,
v is the symmetry-breaking scale, and
is the scalar self-coupling. The metric and vortex ansatz are
where
is the defect gauge coupling,
is the scalar profile, and
is the angular gauge profile.
Introduce the dimensionless radius and angular scale
where
is the Higgs mass scale, and define logarithmic warp derivatives
Introduce also the dimensionless couplings
where
is the six-dimensional gravitational coupling. The matter equations become
with primes denoting
.
A regular unit-winding solution obeys
and approaches an exponentially warped throat,
A numerically reproduced regular control solution is
The near-core coefficients are
and the asymptotic warp exponent is
At
the independent numerical integration gives
while the independent Einstein-constraint residual remains below approximately
over the integration interval. The asymptotic Ricci scalar has magnitude
; in the sign convention used later for the
sector this is written as
The Weyl-tensor square tends numerically to zero. The control therefore verifies a regular, asymptotically conformally flat warped branch without assuming an exact analytic string-cigar profile.
Appendix D.13.5. Normalization of Gauge and Gravitational Zero Modes
For an ordinary spectator Yang–Mills factor labeled by
,
A four-dimensional gauge zero mode that is constant in the transverse coordinates has
For the reproduced solution,
The effective four-dimensional Planck normalization analogously contains
Thus both the spectator gauge zero mode and the graviton zero mode are normalizable on this background.
Appendix D.13.6. Turning-Point Theorem from Localization of a Standard Gauge Zero Mode
The regular vortex above has an angular radius
that grows away from the axis, reaches an interior maximum, and then decreases. This maximum is not merely an accident of the numerical solution. Consider the standard six-dimensional gauge action
where
is a smooth gauge-kinetic weight and
for ordinary Yang–Mills theory. For
one has
. A transverse-constant massless mode
contains two inverse four-dimensional metrics, producing
and cancelling the determinant factor exactly. Therefore
The four-dimensional warp factor does not enter this normalization.
Assume a regular axis,
and suppose that beyond some radius
. If the constant bulk gauge zero mode is normalizable, then
If
never vanished, continuity and the initial condition
would imply
for all
. Hence
would be monotonically increasing and for any fixed
,
It would follow that
contradicting gauge-mode normalizability. Therefore at least one finite radius
must satisfy
Gauge-localization turning theorem.For a smooth regular axisymmetric six-dimensional geometry with , , , and a standard asymptotically nondegenerate bulk gauge kinetic coefficient , normalizability of a transverse-constant four-dimensional gauge zero mode implies the existence of at least one interior turning point . The theorem is independent of the detailed shape of the four-dimensional warp factor because cancels exactly from the gauge kinetic norm.
The distinction between gravity and gauge localization is therefore sharp. If asymptotically
then the graviton norm contains
and may converge for
, whereas the standard constant gauge mode contains only
and requires
. Thus in the whole interval
gravity can remain localized while the ordinary bulk gauge zero mode is not.
Formally one can evade the theorem by taking
fast enough that
remains finite even for nondecaying
L. But the locally canonically normalized non-Abelian coupling then behaves as
Since
in six dimensions, the loop expansion parameter at local energy
E scales as
, and the local weak-coupling cutoff scales as
up to the usual dimensionless NDA coefficient. Hence
drives
. Such a dielectric escape is mathematically possible, but it is not a uniformly weakly coupled local bulk Yang–Mills completion.
Appendix D.13.7. Can a Four-Dimensional Vector Arise from a Tensor Field Instead?
The previous theorem concerned an ordinary six-dimensional one-form potential. In two transverse dimensions one can systematically inspect every standard two-derivative
p-form potential capable of producing a four-dimensional vector. Let
be a
p-form potential with field strength
and positive local kinetic coefficient
. Its standard action is
A four-dimensional vector
arises from
where the
are transverse indices. The two inverse four-dimensional metrics contribute
, which cancels the factor
in
. Therefore every such vector has the universal internal norm
Changing the four-dimensional warp factor cannot by itself localize an otherwise nonnormalizable internal form.
There are only three standard possibilities in two transverse dimensions.
Appendix D.13.8. Nonminimal Escape Through Confinement in the Transverse Bulk
The turning theorem is strict only while the four-dimensional gauge boson is assumed to arise from a weakly coupled local bulk zero mode with a conventional two-derivative kinetic term. A qualitatively different localization mechanism is possible if the phase outside the defect is confining while the relevant subgroup remains Coulombic or deconfined on the defect, as in the general logic of defect gauge localization by bulk confinement [
22]. In that case transverse flux penetration is controlled by the confinement gap rather than by normalizability of a constant perturbative bulk wavefunction. The assumption behind the turning theorem is changed, so there is no contradiction.
It is important first to distinguish genuine confinement from an ordinary positive local mass barrier. For an axisymmetric profile
of an exactly massless four-dimensional vector mode with
, consider
Multiplication by
and integration over
r gives, for regular boundary conditions and a vanishing surface term,
Both terms are nonnegative. A nonzero exactly massless mode is therefore possible only in the degenerate case and on its support. A positive local Proca/Higgs mass profile is not a substitute for confinement; it does not by itself generate a nontrivial exactly massless localized vector.
A genuine confining phase is different because its low-energy response is not represented by such a weakly coupled local Proca profile. For a structural test, assume that flux penetration far from the core is exponentially suppressed by a confinement scale
. If asymptotically
then gravitational localization requires
If the squared transverse gauge amplitude is suppressed as
, its internal norm behaves as
and converges if
Thus there is a nonempty no-turn window
in which gravity is normalizable, gauge response can be localized by a confining gap, and the angular radius can remain monotone without an interior maximum.
An explicit smooth kinematic witness demonstrates that this window is nonempty. Introduce a positive radial scale
and a dimensionless parameter
and take
Near the axis,
while for every finite
,
Hence there is no interior turning point and
. At large radius,
and the Planck normalization is exactly
Figure A4.
Exact no-turn witness in the representative case . The angular radius grows monotonically to a cylinder while the four-dimensional warp factor decays. The plot illustrates the established background geometry only; it does not display the still-uncomputed physical dipole operator or determine .
Figure A4.
Exact no-turn witness in the representative case . The angular radius grows monotonically to a cylinder while the four-dimensional warp factor decays. The plot illustrates the established background geometry only; it does not display the still-uncomputed physical dipole operator or determine .
As required by the earlier theorem, a constant perturbative bulk gauge mode is not normalizable because
diverges. But if the squared penetration amplitude is suppressed as
, with
the confinement-weighted gauge norm is finite and can be written in closed form,
where
is the digamma function. Numerically,
The altered asymptotics are also kinematically compatible with the previously derived one-Weyl normalizability condition. If
and the asymptotic Yukawa mass is
, the large-radius fermion norm reduces to
so convergence requires
The asymptotic behavior of cancels from this condition. A nondecaying asymptotic angular radius is therefore not, by itself, incompatible with the one-Weyl localization mechanism.
What the confinement escape actually proves.The minimal smooth six-dimensional program with a standard weakly coupled bulk gauge zero mode remains limited by the turning theorem and the associated rigidity of the radial breathing sector. This is not an absolute no-go for six dimensions. If four-dimensional gauge localization is instead generated by a genuine confining gap in the transverse bulk, a nonempty smooth no-turn window exists. The stronger result derived below is that a representative geometry in this class is an exact solution of a local two-field Einstein–sigma model with positive kinetic terms and regular winding. Thus the self-consistent-background problem is closed at the effective-field-theory level. The microscopic origin of the confining phase, its scale, the allowed fermion representation, non-axisymmetric perturbations, and the full anomaly/inflow analysis remain separate dynamical criteria.
Appendix D.13.9. Exact Local Matter Support of the Nonminimal No-Turn Cylinder
The confinement-based no-turn construction can be strengthened beyond the kinematic level. Consider the six-dimensional metric
with
The symbol
R denotes the asymptotic radius of the angular circle and
is the dimensionless warp exponent. Near the regular axis,
while
for every finite
r. Thus the circle radius has no interior turning point. The four-dimensional Planck normalization, apart from the angular factor
, is exactly
A local matter source for this geometry is provided by the two-field nonlinear sigma model
where
is the six-dimensional gravitational coupling,
is a canonically normalized radial modulus, and
is a compact phase. For winding number
take
The Einstein equations reconstruct positive radial and angular kinetic energies and yield the exact modulus profile
Define the dimensionless field-space angle
The field-space angular radius and potential are then local functions of
:
Direct substitution satisfies all independent Einstein equations and both scalar equations exactly. The target-space metric is regular at the core because
so the
field space approaches an ordinary polar plane rather than a conical singularity. In particular, no negative kinetic term is required.
The geometry also implies a useful asymptotic necessity. With
and
, the Einstein tensor gives
while
Therefore a standard localized finite-energy vortex whose anisotropic gradients vanish asymptotically, together with an isotropic cosmological term, cannot by itself support the , cylinder. Persistent angular anisotropic stress is necessary.
The same radial modulus can be used as an effective confinement order parameter. If, as an infrared completion hypothesis,
then the corresponding penetration profile is
and its transverse norm is exactly
The existence and finiteness of this norm are exact once the effective gap profile is assumed; the microscopic derivation of from remains open.
Appendix D.13.10. Finite-backreaction Coexistence with a Unit-Winding Abelian–Higgs Vortex
The exact sigma-model source need not be interpreted as a replacement for the previously studied chirality-producing vortex. A separate numerical boundary-value calculation shows that a standard unit-winding Einstein–Abelian–Higgs vortex can coexist with the no-turn stabilizing sector at finite, order-one gravitational backreaction. In the one-parameter exact no-turn family used for this check, positivity of the residual stabilizer stress requires the asymptotic cylinder radius to exceed a gauge-tail threshold,
in the dimensionless normalization of that boundary-value problem. A representative radius
admits a positive coexistence interval extending to approximately
where
is the dimensionless gravitational weight assigned to the Abelian–Higgs vortex stress in the combined reconstruction. In particular, the order-one point
has nonnegative residual radial and winding kinetic terms and a positive residual potential; the reconstructed total stress agrees with the required Einstein tensor to numerical precision.
This result is a numerical existence statement for coexistence, not a derivation of the physical value of . The substantially larger gravitational weight associated with an earlier smooth-vortex control solution, approximately in the same comparison, is not supported by the scanned exact family. That failure constrains this family but is not an absolute no-go for the nonminimal six-dimensional branch, because the stabilizer changes the stress budget and other no-turn families need not have the same upper bound. The full chiral Dirac index and the absence of unwanted mirror zero modes must therefore be rechecked on the combined vortex–stabilizer background rather than inferred from kinematics alone.
Appendix D.13.11. Correction: The Compact Phase Is a Stueckelberg Coordinate, Not an Independent Scalar Zero Mode
A fixed-vector truncation appears to produce a four-dimensional shift mode. If one writes
and sets the Kaluza–Klein vector to zero before varying the action, the coefficient of
is indeed finite:
The integral and the displayed value are algebraically correct, but the interpretation as an additional physical scalar is not. The truncation has frozen the field that gauges angular reparametrizations.
To see the point directly, retain the circle connection in
Under
,
Only the combination is gauge invariant. The apparent constant phase mode can be removed by unitary gauge and is the longitudinal Stueckelberg coordinate of the Kaluza–Klein vector. It must therefore be analyzed together with the vector and Einstein constraints, not counted once more as a free scalar. The regular-axis behavior makes this gauge-invariant description smooth at the cap.
This correction does not claim that every vector or non-axisymmetric perturbation is automatically healthy. It says only that the finite frozen-vector norm does not establish an independent massless scalar. The physical -independent spin-zero sector is the coupled radion–modulus system analyzed next.
Appendix D.13.12. Exact Positive-Square Closure of the Axisymmetric Scalar/Radion Sector
For
reduce the natural no-turn solution on the circle using
and define
After the Stueckelberg coordinate has been removed, the exact five-dimensional Einstein-frame action is
The scalar target metric is the positive matrix
, and
Define the two explicit functions
Direct differentiation and coefficient matching in
give the exact identity
This is an algebraic identity for every
, not a fit to the background. Along the solution,
If
is the five-dimensional Einstein-frame proper coordinate,
the background obeys the first-order flow
where a dot denotes
.
In the conformal coordinate
, write the canonically rescaled physical scalar amplitudes as
For the normalization above, the fake-supergravity part of the coupled metric–scalar operator is generated by
The extra square
vanishes to first order on the background and contributes only
to the scalar potential block. Therefore the full
-independent coupled Hamiltonian is
This is the standard gravity–multi-scalar factorization specialized to the present conventions, with the additional positive rank-one block displayed explicitly [
29]. Its nonzero scalar-block eigenvalue is
at every finite interior point.
For a normalizable eigenmode, integration by parts yields
The five-dimensional circle chart degenerates at
, so the endpoint cannot be assigned an arbitrary self-adjoint extension. Smooth six-dimensional cap regularity requires
and hence
These powers make the cap boundary current vanish. At infinity a normalizable mode has zero flux as well. Consequently
The threshold case requires a separate check because a positive factorization alone does not generally remove multi-scalar zero modes [
30]. If
, both squares vanish. The condition
makes the matter fluctuation tangent to
; by
it can be written as
The remaining first-order equations
reduce exactly to
where
. Near the cap,
With the Frobenius ansatz
the indicial equations give
The branch is singular, while the branch violates the smooth-cap requirement . Setting forces . Thus no nontrivial smooth normalizable zero mode exists.
The asymptotic potentials fall as
, so the essential spectrum begins at
. Zero is a continuum threshold, not a normalizable scalar eigenstate. It is therefore established
for the natural
-independent scalar/radion sector. The benchmark value
gives
; this number checks the regular core limit but is not used in the proof.
Scope of the axisymmetric bulk result.The natural no-turn branch has a positive physical kinetic metric and no normalizable tachyon or scalar zero mode in its full coupled -independent radion–modulus sector. This establishes the absence of an axisymmetric two-derivative effective-field-theory instability for that branch. It does not prove stability of non-axisymmetric harmonics, does not supply an allowed microscopic fermion representation or Yukawa vertex, and does not replace the full six-dimensional anomaly, inflow, confinement, or route-matching calculations.
Appendix D.13.13. Dipole Scalar Clocks and Exact Schur-null Cancellation
The first non-axisymmetric sector,
, is special because it contains the two translations of the smooth defect. A regular real perturbation of the complex sigma field can be written as
Relative to the winding background
, its modulus and phase components are
Whenever
on the open radial domain, this perturbation is a scalar clock for a transverse diffeomorphism. With the convention
,
The apparent factors and polar harmonics do not create a core singularity: the regular Frobenius domain for u and v is precisely the polar representation of a smooth Cartesian vector field. For the benchmark domain, the numerically reconstructed clock also preserves the outer normalizability condition. The negative fixed-metric dipole direction is therefore movable into the metric sector by a globally admissible gauge transformation; it is not, by itself, a gauge-invariant tachyon.
This conclusion can be made exact without assuming a particular projected completion. Let the full on-shell quadratic Hessian in matter and metric variables be
and let an admissible infinitesimal diffeomorphism generated by
X define
The exact diffeomorphism Ward identity is
Its metric component gives
Thus
is the stationary metric completion at fixed
. The full quadratic action on
vanishes exactly. Whenever the metric constraint operator admits the inverse required to define the Schur complement,
one obtains the exact clock-sector identity
The globally reconstructed negative fixed-metric eigenfunction is an admissible scalar-clock image of precisely this type. Consequently its numerical fixed-slice eigenvalue
is not a candidate physical mass. Stationary metric completion removes its fixed-metric Morse index by an exact rank-one cancellation on that direction.
The same statement can be expressed as a finite-dimensional theorem after discretization. Let
be the fixed-metric generalized matter Hessian in kinetic-whitened variables, and let
be the normalized exact translation vector. With
the unique self-adjoint operator that annihilates the translation and leaves the quadratic form on
unchanged is
Its correction has rank at most two,
and
This is an exact Ward-completion theorem; it contains no fitted stabilizing term.
For the stated benchmark discretization, the six lowest fixed-metric eigenvalues in units of
are
whereas the completed spectrum is
The normalized Ward residual is , the low-spectrum reconstruction residual is , and the correction has numerical rank two. The fixed negative mode is strongly localized in the finite core, while its norm beyond is about . These are numerical properties of the displayed benchmark, not universal spectral constants.
The canonical projection remains useful as an independent numerical illustration, but it is not the definition of the physical metric reduction. The Ward identity proves exact Schur-null curvature on the admissible clock image; it does not imply the operator identity
on the full transverse space. Constraint elimination can change the finite-core quadratic form orthogonal to the clock direction and can, in principle, generate a different metric bound state. The remaining question is therefore not whether the former fixed-metric matter mode survives: it does not. The remaining question is whether the independently derived physical metric operator contains another negative normalizable state.
Remaining smooth-branch calculation.One must retain all Kaluza–Klein vector and Einstein lapse/shift variables, solve their regular constraint equations, construct the self-adjoint physical Schur complement with its induced boundary form, and determine its spectrum without identifying it in advance with . A nonnegative operator would establish dipole stability of the smooth no-turn branch under the stated two-derivative assumptions. A negative normalizable eigenvalue would exclude that branch under the same assumptions.
Appendix D.13.14. Exact Birman–Schwinger Reduction of the Remaining Metric Problem
After quotienting the scalar-clock directions and canonically normalizing the physical amplitudes, write the
problem as
on its regular Friedrichs domain. The core regularity, asymptotic, and principal-part results already established above imply
Thus a negative continuum, a cap instability, and a remnant of the removed clock direction are excluded.
Choose a self-adjoint nonnegative reference operator
with the same principal part and asymptotic Friedrichs class as
. Decompose the finite-core form perturbation as
and define
The explicit constrained Einstein second variation must determine
; it is not fixed by the preceding symmetry argument. Under the standard condition that
is relatively form-compact with respect to
, define for
This is a positive compact operator. If
and
, then
The converse follows from the same resolvent identity. Hence
with equality of multiplicities. Moreover,
Because
decreases in the operator order as
increases,
is nonincreasing. If the threshold limit
exists, possibly as
, then
whereas
The equality is a genuine threshold case: the endpoint analysis must distinguish a normalizable zero mode, a zero-energy resonance, and a limiting continuum state. If is trace class, either or the stronger readily evaluated bound is sufficient to exclude negative modes.
There is no universal replacement for this threshold susceptibility by a statement that the gravitational correction is small. The essential spectrum of the nonnegative reference problem begins at zero. For any
, choose a normalized state with
and set
An arbitrarily small attractive operator-norm perturbation can therefore create a negative Rayleigh quotient when the continuum touches zero. The spatial structure of the zero-energy resolvent, encoded by , is indispensable.
The collapse of the first nongauge finite-box level confirms the relevance of this threshold. In units of
, its values for
are respectively
consistent with
. A positive level in a finite radial box is therefore not a uniform stability margin.
For a controlled finite-core calculation, let
be a truncated operator and establish independently
Consequently,
rigorously excludes negative modes, while
rigorously establishes at least one negative mode. If neither inequality holds, the core size, resolution, or tail estimate is insufficient to decide the spectrum. The numerical eigenvalue and its truncation bound must therefore be reported together.
If the attractive part has finite rank,
the nonzero spectrum of
equals the spectrum of the positive
matrix
For rank one,
with
,
whenever the threshold inverse exists on the support of
w. This is an exact simplification if the constrained Einstein kernel is found to be of low rank; no such rank assumption is made in the physical analysis.
The six-dimensional smooth-branch question is therefore reduced to a single well-defined spectral quantity, . Its value is presently unresolved because and require the explicit gauge-invariant Einstein second variation and exact elimination of the nondynamical variables. No fixed-metric matter eigenvalue can substitute for that calculation.
Appendix D.13.15. Finite-Radius Interface Completion and the Boundary-Microphysics Limit
The exact no-turn cylinder above is a consistent effective background when transverse gauge response is attributed directly to bulk confinement. A different question arises if its compact winding is instead gauged by an ordinary local Maxwell–Stueckelberg sector with finite positive kinetic coefficients. In that class the infinite-cylinder stress split cannot be maintained asymptotically: the radial kinetic budget vanishes while a nonzero angular budget remains. Rewriting the same system by bulk Hodge duality as a finite-coupling higher-form BF theory does not change this conclusion, because the BF term is metric independent and the propagating kinetic sectors are locally equivalent.
A conditional classical escape is to retain the same smooth bulk geometry only on a finite interval
and let an effective five-dimensional interface carry the junction stress. Write
and use the gauge-invariant boundary action
For the background covariant winding
define
The induced stress is
and
. With the outward orientation selected by
, the Israel equations give exactly
Thus the interface data are not three freely adjustable coefficients. If
then
and hence
Positive bare tension is equivalent to
Within this window one microscopic equation-of-state ratio fixes the interface radius uniquely.
Maxwell matching also removes the integration constant left by the bulk inverse reconstruction. For
one obtains the exact value
Indeed, if
where
is the positive angular stress budget of the ungauged exact reconstruction, Maxwell matching is precisely
Since , it follows that throughout . The reconstructed Maxwell stress is proportional to and is therefore positive for the decreasing . By continuity on the compact interval, a nonempty sufficiently small range of keeps all reconstructed kinetic functions finite and positive.
This completion is also economical in its independent data. Once
and a microscopic ratio
are fixed, the inversion theorem fixes
. If the microscopic boundary stiffness
is known as well, then
determines
The scalar junction then determines . Thus the classical interface is not an arbitrary functional fit: its remaining difficulty is microscopic origin, not coefficient counting.
The interface scalar equation also closes with no second independent brane function. For outward normal
it is
The fixed-background curvature is positive in the positive-tension window. This is a local background statement, not a proof of the coupled interface fluctuation spectrum.
The exact interface is necessarily flux dominated:
In fact
throughout the positive-tension window. The boundary winding term has a five-dimensional dual description,
in which the four-form carries energy density
and the BF term carries no stress. Therefore
at every finite positive-tension radius.
This stress inequality gives a sharp microscopic no-go theorem. Consider any number of canonical wall scalars
with positive target metric
in a controlled thin-wall decoupling limit, with
and vanishing vacuum wall energy. The one-dimensional first integral gives
This contradicts the exact required inequality . Hence the finite interface cannot be the thin limit of an ordinary positive-potential canonical scalar wall. The theorem does not exclude an intrinsic topological flux brane, a strongly backreacted wall whose thickness is comparable with R, noncanonical or higher-derivative matter, or genuinely nonperturbative confining interface stress.
For the dimensionless benchmark
,
, and
, the exact values are
These numbers are unit checks of the exact formulas, not predictions of the microscopic
theory. Positive tension also truncates the cigar early: the retained Planck fraction obeys
Boundary-microphysics implication.The finite-radius background and its Israel–Maxwell–scalar junction are classically closed with finite positive couplings, and the interface equation of state is one-dimensional rather than freely tunable. However, the required stress cannot originate from an ordinary canonical positive-potential thin wall. Moreover, the smooth infinite-background factorization proved above does not automatically control new interface-localized scalar, vector, or radion modes. The remaining viable origins are a flux-dominated topological interface, a strongly backreacted thick defect, or nonperturbative confining stress. Their flux quantization, global gauge and Dai–Freed consistency, and coupled interface spectrum remain open. Without such microscopic input, further small local scalar, vector, or BF deformations do not decide the six-dimensional theory.
Appendix D.13.16. Exactly One Four-Dimensional Weyl Mode on the Backreacted Geometry
Unit winding invokes the Jackiw–Rossi/Weinberg vortex-index mechanism [
23,
24]; related higher-dimensional vortex constructions localize chiral generations and fermions [
25,
26]. Backreaction changes the radial norm but not the angular index. After the standard spin-connection redefinition, the zero-mode profile behaves asymptotically as
Combining the kinetic norm with
and
gives
At the reproduced background,
Together with the unit-winding index and regularity analysis, this leaves exactly one normalizable four-dimensional Weyl zero mode per vectorlike six-dimensional Dirac parent over a broad Yukawa-coupling range.
Appendix D.13.17. Regularity Surface and the Limit of the Ordinary BPS Mechanism
The self-consistent Einstein–Abelian–Higgs solution is not generic in the full bulk parameter space: the regular gravity-localizing branch lies on a codimension-one regularity surface. For the numerical background, the core relation
is satisfied. Using only the rounded values
and
printed above gives
, which differs from the separately quoted shooting value by
. The agreement is therefore at the level allowed by the unreported parameter digits, not at every displayed digit of
.
Could the ordinary Abelian–Higgs Bogomolnyi limit explain this selection automatically? Direct analysis gives a negative answer. At the critical coupling where the usual first-order BPS equations emerge, the warped branch simultaneously approaches
The exponential gravitational localization then disappears and the four-dimensional Planck integral diverges.
Local no-go theorem and its scope.The ordinary minimal Abelian–Higgs BPS limit does not select the required warped gravity-localizing Einstein–Abelian–Higgs branch. This is a conditional no-go theorem for that specific BPS realization, not for all possible first-order or topological completions.
Appendix D.13.18. Top Form: From a Tuned Local Parameter to an Integration Constant
Introduce a five-form potential
with six-form field strength
A top form in six dimensions has no local propagating degree of freedom; its equation of motion makes
q an integration constant. In physical normalization it shifts the effective cosmological constant according to
Equivalently, introduce dimensionless flux parameters
through
where
is the bare dimensionless cosmological parameter and
is the number of independent top-form sectors. The regular branch reproduced above requires
For the illustrative bare value
,
so one continuous top form requires
The matter and metric profiles are then exactly those already solved at . A codimension-one choice of a local Lagrangian parameter has therefore been converted into the selection of an integration-constant sector. This is a structural improvement, but not an automatic mechanism of radiative self-tuning.
Appendix D.13.19. Quantum Bifurcation: When Must the Flux Be Quantized?
The answer depends on the global higher-form structure.
Appendix D.13.13.1. Source-free noncompact effective-theory branch.
The smooth background has topology
There is no nontrivial compact six-cycle
on which to impose a period condition
Thus, if (Q1) is treated as a source-free top-form sector of the low-energy theory, (Q2) no electrically charged four-branes are introduced, and (Q3) no additional compact six-cycle is added, the constant q remains continuous. Under Q1–Q3 the top form can select the regular background at the level of the effective theory. This does not assert that an unknown quantum-gravity completion must realize precisely this noncompact branch.
Appendix D.13.20. Four Equal Fluxes Fill Arithmetic Shells but Do Not Remove the Radial Spacing
Take
equal-charge top forms with zero offsets and common spacing
,
For
only perfect squares occur. For
not every integer is a sum of two squares. For
, Legendre’s theorem excludes integers of the form
. Lagrange’s four-square theorem guarantees that every nonnegative integer is a sum of four squares. Therefore four equal-charge top forms are sufficient for universal shell coverage,
This is an exact arithmetic statement about angular degeneracy in flux space.
However, the allowed radial values are still
Adding more equal-charge forms increases shell degeneracy but does not reduce the radial spacing . Thus many equal-charge fluxes do not generically solve exact regularity unless the charge scale itself is appropriately aligned. Incommensurate charges can generate a much denser discretuum, but density alone is not a theorem of exact intersection with the required regularity surface.
Appendix D.13.21. Linear Stability Theorem: Transverse-Traceless Gravitational Mode
Consider a four-dimensional transverse-traceless perturbation
Multiplying by
, integrating, and using regular and normalizable boundary conditions gives
Thus the transverse-traceless tensor channel has no tachyons. For , the constant profile is an exact zero mode and is normalizable because .
For completeness, define the asymptotic conformal coordinate
by
and write
. Then
which gives a second proof of nonnegativity. Because
asymptotically,
and the numerical reconstruction gives
. Since
, the tensor continuum begins at
: the localized graviton is a normalizable threshold zero mode rather than a state separated from the continuum by a positive tensor gap.
Appendix D.13.22. Linear Stability Theorem: Spectator non-Abelian Gauge Fields
For a radial mode
of a spectator gauge factor,
The same integration-by-parts argument yields
Hence the spectator gauge sector contains no tachyonic modes. For the constant gauge mode is normalizable because .
Appendix D.13.23. Exact Positivity of the Coupled vortex-U(1) V Vector Channel
The gauge perturbation of the vortex-forming Abelian field is more subtle because it mixes with spin-one metric perturbations. The physical variables must therefore be gauge invariant. The analysis uses the standard gauge-invariant reduction of vector perturbations of a six-dimensional Abelian vortex [
27].
Introduce a conformal radial coordinate
w by
where
x is the dimensionless radial coordinate introduced above. To avoid confusion with the logarithmic warp derivative
, denote the angular Fourier number by
. A gauge-invariant vector master mode
satisfies
where primes in this subsection denote
. Define
Then
and the one-dimensional operator factorizes exactly,
For every regular mode in the operator domain,
where
denotes the factorized vector operator. Therefore
This is an exact no-tachyon theorem for the coupled vortex-vector channel.
For
, the regular zero-mode solution is proportional to the background gauge profile,
Its norm on the regular self-consistent background is
Thus the perturbation problem contains a localized massless vector associated with the vortex . Higgsing the defect field does not, by itself, prove the absence of a four-dimensional massless vector mode. Whether this mode is phenomenologically acceptable, can be identified with an allowed low-energy field, or is lifted by additional ultraviolet structure is a separate model-building question. The theorem establishes only its existence and normalizability within the stated system.
Appendix D.13.24. Independent Graviphoton Zero Modes Are Not Localized
Spin-one metric perturbations contain two independent gauge-invariant combinations, which denote by
and
. Their homogeneous zero-mode solutions behave as
The Einstein–Hilbert norm of
contains
Since
at large
x,
so
diverges. For the homogeneous
solution the norm contains
Near the regular core, and , hence and the integral diverges logarithmically. A separate contribution is algebraically tied to the localized vortex gauge mode, but it is not an additional independent graviphoton degree of freedom. Therefore there are no independent localized graviphoton vector zero modes.
Appendix D.13.25. Absence of a Localized Massless Scalar Modulus
The scalar sector mixes scalar metric perturbations, the real and imaginary Higgs perturbations, and scalar components of the vortex gauge field. A zero-mode analysis alone does not establish positivity of the entire massive scalar spectrum, but the gauge-invariant asymptotics exclude a localized massless modulus [
27]. The full scalar problem must also distinguish this statement from the separate stable transverse metric–gauge channel and from the background radial-breathing, or “sausage”, sector whose boundary-value problem is generically rigid [
28].
One gauge-invariant scalar combination contains an off-diagonal metric perturbation
with
The corresponding canonically weighted field grows and is not normalizable. A diagonal scalar variable
behaves as
so its canonical combination tends to a nonzero constant and its norm diverges linearly in the conformal coordinate. A second metric scalar
has an acceptable constant asymptotic tail but a nonnormalizable core behavior. The remaining scalar variables are algebraically related to these combinations and do not produce an independent normalizable zero state. Hence no localized massless radion, dilaton, or breathing scalar zero mode exists under the stated regularity and asymptotic assumptions.
This is a theorem about zero modes. It does not imply that every massive scalar eigenvalue is nonnegative; that requires the gauge-invariant channel-by-channel analysis discussed below.
Appendix D.13.26. Numerical Nondegeneracy of the Static Boundary-Value Problem
An independent diagnostic asks whether the regular background lies on an obvious continuous family of static solutions. Fix
and
and vary the regular-core parameters
At a finite matching radius
, define the residual vector
The finite-dimensional shooting Jacobian is
After dimensionless row and column scaling, the numerical singular values are
and at fixed
the
block gives
All displayed singular values are nonzero. Within this finite-dimensional shooting subspace there is therefore no infinitesimal static direction that leaves all asymptotic residuals unchanged. This is a strong numerical nondegeneracy check, but it is not a spectral positivity theorem for the full infinite-dimensional scalar Hessian.
Appendix D.13.27. Local Continuation of the Regular Vortex and Top-Form Tracking of the Regular Branch
The absence of a normalizable massless scalar modulus does not imply that the regular vortex is isolated under changes of microscopic parameters. A different question is whether a neighboring regular solution exists when the homogeneous parameters of the Einstein–Abelian–Higgs system are varied slightly.
Together with the effective cosmological parameter
, the coefficients
and
define three shooting variables,
The two dimensionless microscopic parameters controlling the matter and gravitational sectors are
At a large but finite matching radius
, define the independent residual map
The third residual is sufficient because once
,
, and
, the Einstein constraint fixes the common AdS slope,
Thus the regular finite-radius boundary-value problem is locally represented by .
At the refined numerical solution
the finite-difference Jacobian
has
where
is the matrix condition number in the stated dimensionless scaling. The determinant is emphatically nonzero in the reproduced finite-radius problem, so no infinitesimal direction in
leaves all three residuals unchanged.
The implicit-function theorem then has a direct physical interpretation. If the exact infinite-radius boundary map is continuously differentiable and its Jacobian remains nonsingular in the continuum limit, a unique smooth local regularity surface exists,
The theorem is exact; the persistence of the nonsingularity hypothesis in the physical infinite-radius problem is supported numerically rather than proved analytically.
This branch was tested by reintegrating the full nonlinear equations under independent variations of
and
by up to approximately
. The regular solution persists throughout the tested window, with local slopes
The exact core identity
provides an independent derivative check,
and the numerical continuation reproduces these derivatives within the stated integration accuracy.
Now add a source-free six-form with
where
is a spacetime-independent integration constant in each source-free sector. It shifts
For the illustrative value
, the reference regular solution requires
Along the regularity surface, with
fixed,
so
A single continuous nonpropagating integration constant therefore has exactly the local codimension required to follow the regularity surface under sufficiently small homogeneous changes of the vortex parameters.
What the regularity servo solves.Provided the boundary map remains nondegenerate in the continuum and infinite-radius limit, the regular vortex is not an isolated tuned point but lies on a locally smooth regularity surface. A continuous source-free top-form integration constant can track that surface and compensate homogeneous shifts of and without introducing a new local propagating degree of freedom.
Exact limitation.The quantity is a global integration constant, not a field . It therefore cannot provide a Green function for an arbitrary spacetime-dependent perturbation . Homogeneous regularity tracking and local dynamical scalar response are different problems. The gauge-invariant scalar analysis below makes this distinction explicit.
Appendix D.13.28. Full Gauge-Invariant Scalar Decomposition: Transverse Stability, Threshold Locality, and Radial-Breathing Rigidity
Restoring the Einstein scalar constraints changes the interpretation of fixed-geometry matter fluctuations. Two gauge-invariant sectors must be distinguished because they have different physical behavior.
Appendix D.13.13.1. Transverse metric–gauge scalar channel.
For one transverse gauge-invariant combination, all constraint variables can be eliminated exactly. Its master equation reduces to a second-order operator with the factorized positive form
on the physical bounded domain. This excludes a tachyonic branch, and the stated regularity conditions also exclude a normalizable zero mode.
In an asymptotic conformal coordinate
, the operator behaves as
For a compact-core probe, a regular delta-normalized continuum mode therefore behaves at
as
so the threshold spectral measure is
The static susceptibility
has an infrared integrand
and converges. The inverse moments
have threshold integrand
, so
are guaranteed finite. Consequently, the low-momentum core response has the local expansion
where
Q is the magnitude of the four-dimensional Euclidean momentum and the first generic continuum nonanalyticity enters at order
.
Strict result for the transverse scalar channel.Under the stated regular-core assumptions, the full gauge-invariant transverse metric–gauge scalar channel is non-tachyonic, has no normalizable zero mode, has exact asymptotic index , possesses a finite static compact-core response, and admits a local derivative expansion through . This is a result for the full metric-coupled channel, not a Cowling approximation.
Appendix D.13.13.2. Why the fixed-geometry scalar continua are not the full sausage spectrum.
If one artificially imposes , the Higgs-amplitude and gauge-profile fluctuations form a useful matter/Cowling Hessian. Their large inverse-square indices and strong threshold suppression are mathematically meaningful diagnostics. Once the Einstein constraints are restored, however, these matter variables are not an independent physical pair in the background-field sector. The fixed-geometry spectra must therefore not be identified with the complete gauge-invariant scalar spectrum.
Appendix D.13.13.3. Background “sausage” sector.
Gauge-invariant perturbations of fields already nonzero in the background – the Higgs amplitude, the angular vortex gauge profile, and diagonal warp factors – form the system conventionally called the sausage sector in the six-dimensional hyperstring literature [
28]. The local first-order solution space has dimension
Core regularity and finiteness leave
Acceptable asymptotics at infinity remove three growing or divergent branches, so before imposing the internal turning-point regularity condition,
For a regular finite-volume vortex there is an interior point
at which the relevant logarithmic angular derivative satisfies
Regularity of derivative perturbations imposes one further independent linear relation, leaving
The generic intersection in the six-dimensional local solution space is therefore
Generically, only the zero homogeneous sausage perturbation satisfies all core, asymptotic, and turning-point conditions. Published gauge-invariant hyperstring matching likewise found no exceptional acceptable nonzero mode over a broad scanned mass range [
28]. This is not a theorem that a positive massive sausage spectrum exists; it is a stronger statement of generic rigidity or nonpropagation of the homogeneous sausage boundary-value problem under the stated assumptions.
Appendix D.13.13.4. Exact limitation of the top-form repair.
For a source-free top form
Since
is a zero-form in six dimensions,
After Fourier decomposition along the four-dimensional coordinates,
The top-form integration constant can move the background/flux sector and follow the homogeneous regularity surface, but it does not add a local propagating scalar degree of freedom at nonzero four-dimensional momentum. This is an exact limitation: the top form is a background selector, not a sausage Green function.
Correction of the scalar-sector interpretation.The fixed-geometry Higgs–gauge continuum remains mathematically useful, but only as a matter-subsector diagnostic. The full transverse scalar channel has an independent structural stability result. The minimal Einstein–Abelian–Higgs background sausage sector, by contrast, is generically rigid, and the top form cannot repair this rigidity for . The remaining question is therefore specific: does phenomenology require a nonzero local radial-breathing response, and if so, what minimal local structural modification supplies it without reintroducing arbitrary brane coefficients, anomalies, unwanted zero modes, or route-odd spurions?
Appendix D.13.29. Minimal Local Scalar Response from Quadratic Curvature
The rigidity of the background sausage sector motivates a sharply defined question: can one add a single local scalar response channel without introducing an arbitrary brane field or spoiling the fermion and gauge properties already obtained?
The first purely geometric possibility is the Gauss–Bonnet combination
Here
is the six-dimensional Riemann tensor,
the Ricci tensor, and
R the Ricci scalar. In six dimensions this term is dynamical but belongs to the Lovelock class [
31]; its field equations remain second order and, on a nondegenerate background, it does not introduce a new local scalar degree of freedom. It can deform the background, but it does not by itself supply the missing local radial-breathing response.
The minimal curvature modification that does introduce exactly one additional local scalar degree of freedom without an independent massive spin-two ghost is metric
gravity [
32,
33],
Here
has dimensions of inverse curvature. Define
The metric field equations are
where
is the six-dimensional energy–momentum tensor and
. With
the trace equation in
D dimensions is
so in six dimensions
The term is precisely the new local scalar dynamics absent in Einstein gravity and in the nondegenerate Gauss–Bonnet modification.
Let
and
be constant background values and write
In the asymptotic vacuum region
, and
Linearizing the trace equation gives
where
Dividing by
yields the scalaron Klein–Gordon equation
Unlike the top form, this scalar responds locally to and therefore remains dynamical at nonzero four-dimensional momentum.
For the asymptotic
throat, use
and define
The correct sign of the massless graviton kinetic term requires
, and stability of the
sector requires
. Together,
Throughout this interval,
so the scalaron is neither a massless modulus nor a tachyon. As
,
, continuously recovering Einstein gravity at low energy.
As an interior illustrative point, not a fit, take
Define the asymptotic scalaron index
The first generic continuum nonanalyticity therefore scales as ; the low-momentum expansion is analytic through the ordinary even powers below that threshold. More generally, implies , so the compact-core scalaron response is strongly threshold suppressed and infrared finite through several derivative orders.
What is proved for .Within linearization about the asymptotic background, metric gravity adds exactly one local scalar channel and no independent massive spin-two ghost. For , the massless graviton has the correct kinetic sign, the scalaron satisfies , and it couples locally to the trace perturbation . This is the first minimal purely gravitational mechanism considered here that can, in principle, provide a nonzero local scalar response at .
What is not yet proved.This is a linear statement about the asymptotic background. A complete six-dimensional completion would require a self-consistent nonlinear vortex solution in gravity, a reanalysis of its fermion zero modes and gauge localization, and the full gauge-invariant scalar boundary-value problem. The healthy scalaron removes the previous absence of any local scalar candidate; it does not by itself solve the full sausage problem.
Current structural results in the minimal smooth six-dimensional branch.Under the stated assumptions – the charge assignment, direct-product non-Abelian global group, a self-consistent regular Einstein–Abelian–Higgs vortex, and, where invoked, a source-free noncompact top form – local anomalies cancel and the corresponding direct-product bordism obstruction is absent. A backreacted regular vortex is reproduced numerically; exactly one normalizable Weyl zero mode is obtained per vectorlike Dirac parent under the stated Yukawa bound; the graviton and spectator gauge zero modes are normalizable; the tensor, spectator-gauge, and coupled vortex-vector channels are non-tachyonic; independent graviphoton zero modes and a localized massless scalar modulus are absent; and the full transverse scalar channel is stable and threshold-local. The homogeneous background radial-breathing sector remains generically rigid, and a source-free top form changes only the sector.
What remains open in six dimensions.If the ultraviolet completion requires a compact higher-form gauge field and charged four-branes, its charge lattice and exact intersection with the regularity surface must be derived; a dense discretuum is not by itself sufficient. The minimal Einstein–Abelian–Higgs system plus a source-free top form does not provide a general nonzero-Q local response of the background breathing sector. The scalaron is a healthy local candidate, but its sufficiency must be tested in a complete nonlinear vortex. If the non-Abelian global group is quotiented by centers, the bordism analysis must be repeated. The microscopic origin of the defect , the top-form ultraviolet choice, and the orbital involution are not derived from unchanged confining . Finally, the physical route correlator, GEVP poles, and matching residues remain part of the same low-energy nonperturbative test as in four dimensions.
Appendix D.13.30. Why a Healthy Scalaron Does Not Remove the Geometric Turning Condition
The term does create a healthy local scalar degree of freedom in the interval . This does not imply that it removes the extra regularity condition in the background radial-breathing sector.
On the healthy branch of metric
gravity,
so one may perform a regular conformal transformation to the Einstein frame. In six dimensions,
The proper radial element and angular radius become
Because
, a stationary point of the Einstein-frame circle radius obeys
The old Jordan-frame condition is therefore not conformally invariant: the scalaron can move the turning point. But if , away from the regular axis, and at infinity in a finite-volume localizing geometry, continuity forces at least one interior maximum. The turning point is displaced, not eliminated.
In the Einstein frame, healthy gravity is Einstein gravity plus one ordinary scalaron obeying second-order equations. Adding an ordinary second-order scalar increases both the number of local integration constants and the number of regular/asymptotic boundary data. If the independent compatibility condition at the interior turning point remains, the boundary-value deficiency does not change. A healthy scalaron is therefore a genuine local response channel but not automatically a generic completion of the sausage sector.
Appendix D.13.31. Exact Limit of a Finite Local Hamilton–Jacobi Completion
A stronger possibility is to ask whether a finite local Hamilton–Jacobi function can encode the anisotropic angular radius and reduce the radial system to first order. Define
Let
f and
P be the scalar and angular gauge profiles. Consider the most general finite local ansatz involving nonnegative powers of the inverse circle radius,
where
is the highest power and the
are real local functions.
For
, the highest power
in the Hamilton–Jacobi equation has coefficient
For and , every term is nonnegative and the coefficient multiplying is strictly positive. Hence . Iterating the argument reduces every finite ansatz to .
The case
is a scalar-factorized pseudo-superpotential and forces
, which is incompatible with a regular codimension-two axis. The only remaining nontrivial case is
. Core regularity then fixes the functional form almost completely, while the
vacuum condition reduces to
where
is a real integration constant of the one-power ansatz. On the physical branch
,
, and
, the first term is nonnegative, the second strictly positive, and
. The left-hand side cannot vanish.
Local no-go theorem for the tested finite Hamilton–Jacobi class.For the displayed Einstein–Abelian–Higgs potential, including finitely many positive-metric scalar extensions whose highest-power Hamilton–Jacobi contributions enter only through the nonnegative squares shown above, no finite real local ansatz polynomial in nonnegative integer powers of is simultaneously compatible with a regular codimension-two axis and a localizing vacuum. The statement is not a no-go theorem for arbitrary scalar potentials or for noninteger, nonpolynomial, or infinite Hamilton–Jacobi functionals.
This theorem does not exclude nonpolynomial or genuinely infinite Hamilton–Jacobi functionals, new tensor or topological sectors, a new symmetry that changes the constraint algebra, or qualitatively different transverse geometry. It shows only that adding another ordinary scalar or another finite local term has no established mathematical reason to cure the minimal sausage obstruction.
Current physical meaning of the six-dimensional branch.The minimal smooth six-dimensional construction remains strong as a completion of chirality and several zero-mode localization and stability requirements, but its generic local radial-breathing response to an arbitrary four-dimensional source reaches a structural limit. The nonminimal bulk-confinement mechanism changes the assumption responsible for the gauge-localization turning theorem and goes substantially further: the no-turn geometry has an exact positive-kinetic local Einstein–sigma realization, finite-backreaction coexistence with a unit-winding Abelian–Higgs vortex occurs in a nonempty numerical window, and the complete coupled -independent radion–modulus operator is nonnegative with no normalizable zero mode. The earlier frozen-KK-vector phase mode is not an independent scalar. In the regular dipole sector the former fixed-metric negative eigenfunction is an admissible scalar-clock image, and the exact Ward identity makes its stationary metric completion Schur-null; hence is not a physical mass. The remaining gauge-invariant metric problem has been reduced exactly to the threshold Birman–Schwinger number , but the explicit constraint-reduced potential and the value of have not yet been computed. The six-dimensional branch is therefore prospective rather than complete: the physical dipole and higher harmonics, interface-localized modes, microscopic confining sector, admissible fermion representation and Yukawa coupling, full anomaly/inflow analysis, and route matching remain open.