arXiv subjects

Ashwin S. Pande

Publications and source records attributed to Ashwin S. Pande.

6 recordsLinked to original sources

arXiv2025

On Higher Topological T-duality Functors

We use String Field Theory (SFT) to construct a higher analogue of Bunke-Schick's functor $P: \mathbf{Top}^{op} \to \mathbf{Set}$ \cite{BunkeS1} by geometrizing $P.$ We use the projection of SFT onto its massless modes \cite{SFTDiffeo} to construct the category $\C$ whose objects are pairs (which we identify with SFT backgrounds) and whose maps are morphisms of pairs (which are gauge transformations). Using $\C$ and categorical equivalence, for any $CW-$complex $X$ we define the moduli space $G(X)$ of SFT backgrounds which are pairs over $X$ up to gauge equivalence. We use the homotopy theory of the moduli space $G(X)$ to define functors on the category of $CW-$complexes $P_k:\mathbf{CW}^{op} \to \mathbf{Grpd}$ such that $P_0 \simeq P,$ $P_1$ is nontrivial and $P_k(X)$ are always trivial for $k \geq 2.$ Arrows in $P_1(X)$ are shown to be isotopy classes of maps in the mapping class group of $X$ acting on (isomorphism classes of) pairs over $X.$ We discuss applications to Topological T-duality for triples and to modelling doubled geometries and T-folds \cite{HullT}.

math-ph↗

arXiv2023

Topological T-duality for bundles of strongly self-absorbing C*-algebras and some physical applications

We extend the $C^{\ast}-$algebraic formalism of Topological T-duality to section algebras of locally trivial bundles of strongly self-absorbing $C^{\ast}-$algebras and to a larger class of String Theoretic dualities. We argue that physically this corresponds extending Topological T-duality to Flux Backgrounds of Type II String Theory which possess topologically nontrivial sourceless Ramond-Ramond flux. We demonstrate a map in $K-$theory for the $C^{\ast}-$algebras involved in both sides of this generalized duality. We calculate a few examples. We discuss the physical relevance of the above formalism in some detail, in particular, we argue that the above formalism models String Theoretic tree-level dualities found in such Flux Backgrounds such as Fermionic T-duality and Timelike T-duality.

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arXiv2017

Topological T-duality for Stacks using a Gysin Sequence

In this paper we study the topological T-dual of spaces with a non-free circle action mainly using the stack theory method of Bunke and co-workers \cite{Bunke1}. We first compare three formalisms for obtaining the Topological T-dual of a semi-free $S^1$-space in a simple example. Then, we calculate the T-dual of general KK-monopole backgrounds using the stack theory method. We define the dyonic coordinate for these backgrounds. We introduce an approach to Topological T-duality using classifying spaces which simultaneously generalizes the methods of Bunke et al \cite{Bunke1} and Mathai and Wu \cite{MaWu}. Then, we define a cohomology Gysin sequence for prinicpal bundles of stacks and describe an application to Topological T-duality for stacks. We apply the above to calculate the Topological T-dual of a general compact three-manifold with an {\em arbitrary} smooth circle action. We point out a possible application of these T-duals to higher-dimensional black holes.

math-ph↗

arXiv2013

Topological T-duality, Automorphisms and Classifying Spaces

We extend the formalism of Topological T-duality to spaces which are the total space of a principal $S^1$-bundle $p:E \to W$ with an $H$-flux in $H^3(E,Z)$ together the together with an automorphism of the continuous-trace algebra on $E$ determined by $H$. The automorphism is a `topological approximation' to a gerby gauge transformation of spacetime. We motivate this physically from Buscher's Rules for T-duality. Using the Equivariant Brauer Group, we connect this problem to the $C^{\ast}$-algebraic formalism of Topological T-duality of Mathai and Rosenberg. We show that the study of this problem leads to the study of a purely topological problem, namely, Topological T-duality of triples $(p,b,H)$ consisting of isomorphism classes of a principal circle bundle $p:X \to B$ and classes $b \in H^2(X,Z)$ and $H \in H^3(X,Z).$ We construct a classifying space $R_{3,2}$ for triples in a manner similar to the work of Bunke and Schick \cite{Bunke}. We characterize $R_{3,2}$ up to homotopy and study some of its properties. We show that it possesses a natural self-map which induces T-duality for triples. We study some properties of this map.

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arXiv2008

Topological T-duality and T-folds

We explicitly construct the C*-algebras arising in the formalism of Topological T-duality due to Mathai and Rosenberg from string-theoretic data in several key examples. We construct a continuous-trace algebra with an action of ${\mathbb R}^d$ unique up to exterior equivalence from the data of a smooth ${\mathbb T}^d$-equivariant gerbe on a trivial bundle $X = W \times {\mathbb T}^d$. We argue that the `noncommutative T-duals' of Mathai and Rosenberg, should be identified with the nongeometric backgrounds well-known in string theory. We also argue that the crossed-product C*-algebra ${\mathcal A} \rtimes_{α|_{\KZ^d}} {\mathbb Z}^d$ should be identified with the T-folds of Hull which geometrize these backgrounds. We identify the charge group of D-branes on T-fold backgrounds in the C*-algebraic formalism of Topological T-duality. We also study D-branes on T-fold backgrounds. We show that the $K$-theory bundles studied by Echterhoff, Nest and Oyono-Oyono give a natural description of these objects.

hep-th↗

arXiv2007

Topological T-duality and Kaluza-Klein Monopoles

We study topological T-duality for spaces with a semi-free $S^1-$action with isolated fixed points. Physically, these correspond to spacetimes containing Kaluza-Klein monopoles. We demonstrate that the physical dyonic coordinate of such spaces has an analogue in our formalism. By analogy with the Dirac monopole, we study these spaces as gerbes. We study the effect of Topological T-duality on these gerbes.

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