arXiv subjects

Yuri Ximenes Martins

Publications and source records attributed to Yuri Ximenes Martins.

10 recordsLinked to original sources

arXiv2021

Existence of $B^k_{α,β}$-Structures on $C^k$-Manifolds

In this paper we introduce $B_{α,β}^{k}$-manifolds as generalizations of the notion of smooth manifolds with $G$-structure or with $k$-bounded geometry. These are $C^{k}$-manifolds whose transition functions $φ_{ji}=φ_{j}\circφ_{i}^{-1}$ are such that $\partial^μφ_{ji}\in B_{α(r)}\cap C^{k-β(r)}$ for every $\vertμ\vert=r$, where $B=(B_{r})_{r\inΓ}$ is some sequence of presheaves of Fréchet spaces endowed with further structures, $Γ\subset\mathbb{Z}_{\geq0}$ is some parameter set and $α,β$ are functions. We present embedding theorems for the presheaf category of those structural presheaves $B$. The existence problem of $B_{α,β}^{k}$-structures on $C^{k}$-manifolds is studied and it is proved that under certain conditions on $B$, $α$ and $β$, the forgetful functor from $C^{k}$-manifolds to $B_{α,β}^{k}$-manifolds has adjoints.

math.DG↗

arXiv2021

Geometric Regularity Results on $B_{α,β}^{k}$-Manifolds, I: Affine Connections

In this paper we consider existence and multiplicity results concerning affine connections on $C^{k}$-manifolds $M$ whose coefficients are as regular as one needs, following the regularity theory introduced in arXiv:1908.04442. We show that if $M$ admits a $B_{α,β}^{k}$-structure, then the existence of such regular connections can be established in terms of properties of the structural presheaf $B$. In other words, we propose a solution to the existence problem in this setting. With regard to the multiplicity problem, we show that the space of regular affine connections is an affine space of the space of regular $\operatorname{End}(TM)$-valued 1-forms, and that if two regular connections are locally additively different, then they are actually locally different. The existence of a topology in which the space of regular connections is a nonempty open dense subset of the space of all regular $\operatorname{End}(TM)$-valued 1-forms is suggested.

math.DG↗

arXiv2020

An Axiomatization Proposal and a Global Existence Theorem for Strong Emergence Between Parameterized Lagrangian Field Theories

In this paper we propose an axiomatization for the notion of strong emergence phenomenon between field theories depending on additional parameters, which we call parameterized field theories. We present sufficient conditions ensuring the existence of such phenomena between two given Lagrangian theories. More precisely, we prove that a Lagrangian field theory depending linearly on an additional parameter emerges from every multivariate polynomial theory evaluated at differential operators which have well-defined Green functions (or, more generally, that has a right-inverse in some extended sense). As a motivating example, we show that the phenomenon of gravity emerging from noncommutativy, in the context of a real or complex scalar field theory, can be recovered from our emergence theorem. We also show that, in the same context, we could also expect the reciprocal, i.e., that noncommutativity could emerge from gravity. Some other particular cases are analyzed.

math-ph↗

arXiv2020

On Maximal, Universal and Complete Extensions of Yang-Mills-Type Theories

In this paper we continue the program on the classification of extensions of the Standard Model of Particle Physics started in arXiv:2007.01660. We propose four complementary questions to be considered when trying to classify any class of extensions of a fixed Yang-Mills-type theory $S^G$: existence problem, obstruction problem, maximality problem and universality problem. We prove that all these problems admits a purely categorical characterization internal to the category of extensions of $S^G$. Using this we show that maximality and universality are dense properties, meaning that if they are not satisfied in a class $\mathcal{E}(S^G;\hat{G})$, then they are in their "one-point compactification" $\mathcal{E}(S^G;\hat{G})\cup \hat{S}$ by a specific trivial extension $\hat{S}$. We prove that, by means of assuming the Axiom of Choice, one can get another maximality theorem, now independent of the trivial extension $\hat{S}$. We consider the class of almost coherent extensions, i.e, complete, injective and of pullback-type, and we show that for it the existence and obstruction problems have a complete solution. Using again the Axiom of Choice, we prove that this class of extensions satisfies the hypothesis of the second maximality theorem.

math-ph↗

arXiv2020

On Extensions of Yang-Mills-Type Theories, Their Spaces and Their Categories

In this paper we consider the classification problem of extensions of Yang-Mills-type (YMT) theories. For us, a YMT theory differs from the classical Yang-Mills theories by allowing an arbitrary pairing on the curvature. The space of YMT theories with a prescribed gauge group $G$ and instanton sector $P$ is classified, an upper bound to its rank is given and it is compared with the space of Yang-Mills theories. We present extensions of YMT theories as a simple and unified approach to many different notions of deformations and addition of correction terms previously discussed in the literature. A relation between these extensions and emergence phenomena in the sense of arXiv:2004.13144 is presented. We consider the space of all extensions of a fixed YMT theory $S^G$ and we prove that for every additive group action of $\mathbb{G}$ in $\mathbb{R}$ and every commutative and unital ring $R$, this space has an induced structure of $R[\mathbb{G}]$-module bundle. We conjecture that this bundle can be continuously embedded into a trivial bundle. Morphisms between extensions of a fixed YMT theory are defined in such a way that they define a category of extensions. It is proved that this category is a reflective subcategory of a slice category, reflecting some properties of its limits and colimits.

math-ph↗

arXiv2020

Introduction to Abstract Homotopy Theory

This is an introduction to the study of abstract homotopy theory by means of model categories and $(\infty,1)$-categories. The only prerequisites are very basic general topology and abstract algebra. None categorical background is needed. The final objective is to show that classical homotopy theory for topological spaces can be more naturally understood in terms of categorical language.

math.AT↗

arXiv2020

Towards Axiomatization and General Results on Strong Emergence Phenomena Between Lagrangian Field Theories

In this paper we propose a formal definition of what is a strong emergence phenomenon between two parameterized field theories and we present sufficient conditions ensuring the existence of such phenomena between two given parameterized Lagrangian field theories. More precisely, we prove that in an Euclidean background, typical parameterized kinetic theories emerge from any elliptic multivariate polynomial theories. Some concrete examples are given and a connection with the phenomenon of gravity emerging from noncommutativity is made.

math-ph↗

arXiv2019

Geometric Obstructions on Gravity

These are notes for a short course and some talks gave at Departament of Mathematics and at Departament of Physics of Federal University of Minas Gerais, based on the author's paper arXiv:1808.09249. Some new information and results are also presented. Unlike the original work, here we try to give a more physical emphasis. In this sense, we present obstructions to realize gravity, modeled by the tetradic Einstein-Hilbert-Palatini (EHP) action functional, in a general geometric setting. In particular, we show that if spacetime has dimension $n\geq4$, then the cosmological constant plays no role in any "concrete geometries" other than Lorentzian. If $n\geq6$, then the entire EHP theory is trivial, meaning that Lorentzian geometry is (essentially) the only "concrete geometry" in which gravity (i.e, the EHP action functional) makes sense. Examples of "concrete geometries" include those locally modeled by group reductions $H\hookrightarrow O(k;A)$ for some $k$ and some algebra $A$, so that Riemannian geometry, Hermitian geometry, Kähler geometry and symplectic geometry, as well as Type II geometry, Hitchin's generalized complex geometry and $G_{2}$-geometry are included. We also study EHP theory in "abstract geometries", such as graded geometry (and hence supergeometry), and we show how the obstruction results extend to this context. We construct two theories naturally associated to EHP, which we call the geometric/algebraic dual of EHP, and we analyze the effect of the obstructions in these new theories. Finally, we speculate (and provide evidence for) the existence of a "universal obstruction condition".

math-ph↗

arXiv2019

Existence and Classification of Pseudo-Asymptotic Solutions for Tolman-Oppenheimer-Volkoff Systems

The Tolman--Oppenheimer--Volkoff (TOV) equations are a partially uncoupled system of nonlinear and non-autonomous ordinary differential equations which describe the structure of isotropic spherically symmetric static fluids. Nonlinearity makes finding explicit solutions of TOV systems very difficult and such solutions and very rare. In this paper we introduce the notion of pseudo-asymptotic TOV systems and we show that the space of such systems is at least fifteen-dimensional. We also show that if the system is defined in a suitable domain (meaning the extended real line), then well-behaved pseudo-asymptotic TOV systems are genuine TOV systems in that domain, ensuring the existence of new fourteen analytic solutions for extended TOV equations. The solutions are classified according to the nature of the matter (ordinary or exotic) and to the existence of cavities and singularities. It is shown that at least three of them are realistic, in the sense that they are formed only by ordinary matter and contain no cavities or singularities.

math.CA↗

arXiv2019

Graph Reconstruction, Functorial Feynman Rules and Superposition Principles

In this article functorial Feynman rules are introduced as large generalizations of physicists Feynman rules, in the sense that they can be applied to arbitrary classes of hypergraphs, possibly endowed with any kind of structure on their vertices and hyperedges. We show that the reconstruction conjecture for classes of (possibly structured) hypergraphs admit a sheaf-theoretic characterization, allowing us to consider analogous conjectures. We propose an axiomatization for the notion of superposition principle and prove that the functorial Feynman rules work as a bridge between reconstruction conjectures and superposition principles, meaning that a conjecture for a class of hypergraphs is satisfied only if each functorial Feynman rule defined on it induces a superposition principle. Applications in perturbative euclidean quantum field theory and graph theory are given.

math-ph↗