Study on decay rates of higher derivatives for nonlinear Dirac equations.
problem Estimating decay rates of higher derivatives of solutions to nonlinear Dirac equations.
method Similar to Li and Zang's method, focusing on 'good' spin null form.
result Obtained decay rates of higher derivatives of solutions.
The paper explores Einstein warped G2 and Spin(7) manifolds.
problem Understanding Einstein warped G2 and Spin(7) manifolds.
method Warped G2 and Spin(7) structures with Einstein fiber are studied.
result Explicit descriptions of torsion forms for these structures.
Study finds holonomy algebras for Lorentzian Weyl spin manifolds with specific spinors.
problem Characterizing Lorentzian Weyl spin manifolds with weighted parallel spinors.
method Analyzing holonomy algebras and introducing special coordinates.
result Local forms and examples of Lorentzian Weyl spin manifolds with weighted parallel spinors.
Study spin-0 fields on n-dimensional Minkowski spacetimes, computing asymptotic charges.
problem Analyzing spin-0 fields on Minkowski spacetimes near infinity.
method Conformal geometry and Friedrich's cylinder at spatial infinity.
result Found infinitely many well-defined asymptotic charges in even dimensions, no charges in odd dimensions.
Notation for spin coefficients for metrics of neutral signature in four dimensions is introduced. The utility and interpretation of spin coefficients is explored through themes in null geometry familiar from (complex) general relativity. Four-dimensional Walker geometry is exploited to provide examples and the generali…
We prove that an (n+1)-dimensional spin static vacuum with negative cosmological constant whose null infinity has a boundary admitting a non-trivial Killing spinor field is the AdS spacetime. As a consequence, we generalize previous uniqueness results by X. Wang \cite{Wa2} and by Chru{ś}ciel-Herzlich \cite{CH} and in…
Study null curves and their motion in 3D flat space-time, leading to integrable hierarchies.
problem Understanding null curves and their motion in 3D flat space-time.
method Analyzing the motion of null curves and their surfaces, deriving integrability conditions and hierarchies.
result Obtained one- and two-soliton surfaces associated with the MKdV equation, showing singularities in finite time.
We determine the geometry of supersymmetric heterotic string backgrounds for which all parallel spinors with respect to the connection ∇^ with torsion H, the NS⊗NS three-form field strength, are Killing. We find that there are two classes of such backgrounds, the null and the timelike. The Killing s…
Extends spinor-horosphere correspondence to higher dimensions and new spinor types.
problem Constructing isomorphisms between spinors and horospheres in hyperbolic spaces.
method Generalizes Mathews' results to Lipschitz spinors and null multiflags in higher-dimensional hyperbolic spaces.
result Equivariant correspondence between two-component Lipschitz spinors and higher-dimensional horospheres.
We study the geometric properties of a 2m-dimensional complex manifold M admitting a holomorphic reduction of the frame bundle to the structure group P⊂Spin(2m,C), the stabiliser of the line spanned by a pure spinor at a point. Geometrically, M is endowed with a hol…
Deep networks show less disorder and more monotonic behavior.
problem Understanding the disorder and monotonicity in deep neural networks.
method Computing frustration and analyzing near-monotonicity in signed graphs of deep networks.
result Deep networks exhibit less disorder and more monotonic behavior than expected.
Frame-spun knots are constructed by spinning a knot of lower dimension about a framed submanifold of S^n. We show that all frame-spun knots are slice (null-cobordant).
In this study, we define a family of null curves in Minkowski 3-space and called null similar curves. We obtain some properties of these special curves. We show that two null curves are null similar curves if and only if these curves form a null Bertrand pair. Moreover, we obtain that the family of null geodesics and n…
We study the geometric properties of a (2m+1)-dimensional complex manifold M admitting a holomorphic reduction of the frame bundle to the structure group P⊂Spin(2m+1,C), the stabiliser of the line spanned by a pure spinor at a point. Geometrically, M is endowed with…
New types of null hypersurfaces found in Sasakian space-forms.
problem Identifying new structures in Sasakian space-forms.
method Defined and analyzed contact screen conformal and umbilic null hypersurfaces.
result Proved these hypersurfaces exist in Sasakian space forms with specific curvature.
The paper studies special null hypersurfaces in spacetimes.
problem Characterizing null screen isoparametric hypersurfaces in Lorentzian space forms.
method Developed screen isoparametric hypersurface concept for null hypersurfaces of Robertson-Walker spacetimes, derived Cartan identities, and provided local characterizations.
result Derived Cartan identities for the screen principal curvatures of null screen hypersurfaces in Lorentzian space forms and provided a local characterization.
Extends LOSS invariant naturality to positive contact surgeries.
problem Naturality of LOSS invariant under positive contact surgeries.
method Proves naturality of LOSS invariant for Legendrian knots under positive integer contact surgeries.
result Contact invariant of +n surgery depends only on classical invariants of S.
Study on spin-zero rest-mass fields using conformal geometric method.
problem Wellposedness of Cauchy and Goursat problems for spin-n/2 zero rest-mass equations. method Conformal geometric method, energy equalities, partial conformal compactification.
result Proves wellposedness of Cauchy and Goursat problems and establishes field decays.
New formula found for a unique invariant 8-form on Riemannian manifolds with Spin(9) structure.
problem Finding a new explicit algebraic formula for a unique invariant 8-form.
method Generalizing the standard Kähler 2-form expression, constructing the invariant 8-form from octonion-valued coordinate 1-forms.
result A new explicit algebraic formula for the Spin(9)-invariant 8-form. The paper explores connections between quaternionic and Cayley calibrations in dimensions 8 and 16.
problem Exploring connections between quaternionic and Cayley calibrations in dimensions 8 and 16.
method Starting from collections of 'Kähler 2-forms', the paper constructs canonical 4-forms and calibrated 4-planes in dimensions 8 and 16.
result Explicit formulas for canonical 4-forms ΦSpin(8) and ΦSpin(7)U(1) are derived, and their calibrated 4-planes are characterized. Paper proves rigidity for spin bands with specific conditions.
problem Proving rigidity for initial data sets on spin bands.
method Using Dirac operator techniques and lightlike imaginary W-Killing spinors. result Obtains slight generalizations of known rigidity results.
Spin(7) geometry linked to multisymplectic geometry.
problem Understanding Spin(7) structures through multisymplectic geometry.
method Utilized Spin(7) identities to prove non-degeneracy of Cayley four-form in multisymplectic context.
result Spin(7) geometry is a special case of multisymplectic geometry.
The paper characterizes spin initial data sets saturating the BPS bound in asymptotically AdS spacetimes.
problem Characterizing spin initial data sets saturating the BPS bound in asymptotically AdS spacetimes.
method The paper introduces a theorem for replacing imaginary Killing spinors with strictly timelike or null ones and uses spinors to construct a codimension-2 slicing.
result The paper establishes a sharp dimension threshold for saturating the BPS bound in gravitational waves and rotating black holes in higher dimensions.
We give a local integral formula, valid on general curved space-times, for the characteristic Cauchy problem for the Dirac equation with arbitrary spin using the method developed by Friedlander in his book "the wave equation on a curved spacetime" (1975). The results obtained by Penrose in the flat case in "Null hypers…
Constructs modular forms and proves divisibility results for odd-dimensional manifolds.
problem Constructing modular forms over specific groups and proving divisibility results.
method SL(2, Z) modular forms and Witten genus in odd dimensions.
result Obtained divisibility results of index of Toeplitz operators on spin and spin^c manifolds.
New cubic forms linked to η-invariants and mod 2 indices.
problem Anomaly cancellation and modularity in 12-manifolds.
method Combination of Witten classes and affine E8 character. result Relates cubic forms to η-invariants and mod 2 indices.
In 1986, Matveev defined the notion of Borromean surgery for closed oriented 3-manifolds and showed that the equivalence relation generated by this move is characterized by the pair (first betti number, linking form up to isomorphism). We explain how this extends for 3-manifolds with spin structure if we replace the li…
Study on instantons in G2 and Spin(7) manifolds.
problem Investigate instanton properties in G2 and Spin(7) manifolds. method Analyze the characteristic and torsion connections on G2 and Spin(7) manifolds, focusing on parallel torsion and Lee forms. result Conditions for the curvature of the characteristic connection to be a G2 instanton and for the torsion connection to be a Spin(7) instanton are established. New formulas derived from modular forms for manifold indices.
problem Calculating indices of twisted Dirac operators on manifolds.
method SL(2, Z) modular forms and Γ^0(2), Γ_0(2) forms.
result New anomaly cancellation formulas for spin and spin^c manifolds.
Functional for Spin(7) forms defined on compact manifolds.
problem Characterizing conformal Spin(7) forms on Riemannian manifolds.
method Algebraic equation of degree two for self-dual four-forms, construction of a functional.
result Construction of a functional whose critical points are conformally Ricci-flat Spin(7) structures.
New elliptic genera defined for spin manifolds.
problem Defining new elliptic genera for spin manifolds.
method Defined new two-variable elliptic genera using Jacobi forms and modular forms.
result Anomaly cancellation formulas derived from modular forms.
Null Lagrangian-preserving surgeries are a generalization of the Garoufalidis and Rozansky null-moves, that these authors introduced to study the Kricker lift of the Kontsevich integral, in the setting of pairs (M,K) composed of a rational homology sphere M and a null-homologous knot K in M. They are defined as replace…
Study of null hypersurfaces in semi-Riemannian manifolds with applications.
problem Characterize null hypersurfaces in semi-Riemannian manifolds with varying sectional curvature.
method Introduce screen quasi-conformal hypersurfaces and extend results to non-zero sectional curvature.
result Classification results for umbilical, isoparametric, and Einstein null hypersurfaces in Lorentzian space forms.
The paper studies curvature identities and solitons on Spin(7)-manifolds.
problem Curvature identities and solitons on Spin(7)-manifolds.
method Analyzes the curvature and torsion of Spin(7)-manifolds, proving identities and conditions.
result Conditions for closed torsion and implications for Ricci flatness and solitons.
Extends Penrose's method to null shells with pressure and energy flux.
problem Constructing null thin shells with arbitrary gravitational/matter content.
method Derive locally Lipschitz metric and coordinate transformation.
result Example of null shell with non-trivial energy density, flux, and pressure in Minkowski space.
Study on special null submanifolds in indefinite Sasakian manifolds.
problem Characterizing null submanifolds in indefinite Sasakian manifolds.
method Proving properties of screen conformal null submanifolds and defining a new class.
result Existence of contact screen conformal r-null submanifolds in indefinite Sasakian space forms. This paper explores 4-planes in Spin(7) manifolds with symplectic structures.
problem Characterizing 4-planes in Spin(7) manifolds with symplectic structures.
method Detailed analysis of differential forms, including the Cayley 4-form, and exploration of mirror duality.
result Enhanced understanding of the interplay between Spin(7)-structures and symplectic geometry.
Using Seiberg-Witten Floer spectrum and Pin(2)-equivariant KO-theory, we prove new Furuta-type inequalities on the intersection forms of spin cobordisms between homology 3-spheres. As an application, we give explicit constrains on the intersection forms of spin 4-manifolds bounded by Brieskorn spheres $\pmΣ(2,3,6k\…
Let X be a smooth closed oriented non-spin 4-manifold with even intersection form kE_8\oplus nH. In this article we show that n\geq |k| on X. Thus we confirm the 10/8-conjecture affirmatively. As an application, we also give an estimate of intersection forms of spin coverings of non-spin 4-manifolds with even intersect…
Proves stability of charged black holes with small charge.
problem Linear stability of Reissner-Nordström spacetime for small charge.
method Proves stability of Reissner-Nordström family of charged black holes using linearized Einstein-Maxwell equations and geodesic null foliations.
result Solutions decay to a linearized Kerr-Newman metric, proving stability.
Reviews interactions between Spin(9) and octonionic geometries.
problem Understanding the role of Spin(9) in octonionic geometry.
method Analyzes canonical 8-forms, vector fields, Hopf fibrations, and manifolds.
result Discovers new insights into the geometry of octonionic Hopf fibrations.
A new spin structure is constructed for a bundle of harmonic forms.
problem Constructing a spin structure for a bundle of harmonic forms.
method Using families Seiberg-Witten equations to construct a lifting O(1)-gerbe.
result A canonical spin structure is constructed for the bundle TBX⊕π∗H+(X). Study optimal transport on null hypersurfaces and null energy condition.
problem Optimal transport degeneracy on null hypersurfaces.
method Developed tools to characterize null energy condition using convexity properties of entropy.
result Optimal transport characterization of null energy condition.
Motivated by recent work of Choquet-Bruhat, Chrusciel, and Martin-Garcia, we prove monotonicity properties and comparison results for the area of slices of the null cone of a point in a Lorentzian manifold. We also prove volume comparison results for subsets of the null cone analogous to the Bishop-Gromov relative volu…
Proves boundedness and decay for spin 2 Teukolsky system on Reissner-Nordström spacetime.
problem Analyzing stability of Reissner-Nordström spacetime for small charge.
method Derived quantities and generalized coupled Regge-Wheeler system.
result Proves boundedness and polynomial decay for spin 2 solutions.
We describe the geometry of geodesics on a Lorentz ellipsoid: give explicit formulas for the first integrals (pseudo-confocal coordinates), curvature, geodesically equivalent Riemannian metric, the invariant area-forms on the time- and space-like geodesics and invariant 1-form on the space of null geodesics. We prove a…
Study peels tensor equations on Schwarzschild spacetime.
problem Analyzing the asymptotic behavior of tensorial wave equations on Schwarzschild spacetime.
method Combining conformal compactification and vector field techniques to estimate tensorial field energies.
result Obtains optimal initial data for peeling at all orders.
There is a class of Laplacian like conformally invariant differential operators on differential forms Lkℓ which may be considered the generalisation to differential forms of the conformally invariant powers of the Laplacian known as the Paneitz and GJMS operators. On conformally Einstein manifolds we give explic…