arXiv subjects

Omar Kidwai

Publications and source records attributed to Omar Kidwai.

7 recordsLinked to original sources

arXiv2025

Spectral networks for polynomial cubic differentials

We study cubic differentials and their spectral networks on Riemann surfaces, focusing on the polynomial case on the Riemann sphere. We introduce the notion of spectral core as the primary tool for our study, refining the classical notion of core in the theory of flat surfaces, and show that it controls the birthing process of spectral network trajectories. As an application, we completely characterize the polynomial cubic differentials having saddle connections or critical tripods when the degree $d$ is at most $3$; in particular, we obtain the relevant degenerations as the phase is varied and determine explicitly the wall-and-chamber structure. In this case, we obtain the BPS structure according to Gaiotto-Moore-Neitzke's algorithm, and verify that it satisfies the Kontsevich-Soibelman wall-crossing formula. In physics language, this corresponds to computing the BPS spectrum of a certain four-dimensional $\mathcal{N}=2$ quantum field theory, known as the $(A_{2},A_{d-1})$ generalized Argyres-Douglas theory.

math.AG↗

arXiv2024

Donaldson-Thomas invariants for the Bridgeland-Smith correspondence

Famous work of Bridgeland and Smith shows that certain moduli spaces of quadratic differentials are isomorphic to spaces of stability conditions on particular 3-Calabi-Yau triangulated categories. This result has subsequently been generalised and extended by several authors. One facet of this correspondence is that finite-length trajectories of the quadratic differential are related to categories of semistable objects of the corresponding stability condition, which have associated Donaldson-Thomas invariants. On the other hand, computations in the physics literature suggest certain values of these invariants according to the type of trajectory. In this paper, we show that the category recently constructed by Christ, Haiden, and Qiu gives Donaldson-Thomas invariants which agree with the predictions from physics; in particular, degenerate ring domains of the quadratic differential give rise to non-zero Donaldson-Thomas invariants. In calculating all of the invariants, we obtain a novel application of string and band techniques from representation theory.

math.AG↗

arXiv2024

Topological recursion and uncoupled BPS structures II: Voros symbols and the $τ$-function

We continue our study of the correspondence between BPS structures and topological recursion in the uncoupled case, this time from the viewpoint of quantum curves. For spectral curves of hypergeometric type, we show the Borel-resummed Voros symbols of the corresponding quantum curves solve Bridgeland's "BPS Riemann-Hilbert problem". In particular, they satisfy the required jump property in agreement with the generalized definition of BPS indices $Ω$ in our previous work. Furthermore, we observe the Voros coefficients define a closed one-form on the parameter space, and show that (log of) Bridgeland's $τ$-function encoding the solution is none other than the corresponding potential, up to a constant. When the quantization parameter is set to a special value, this agrees with the Borel sum of the topological recursion partition function $Z_{\rm TR}$, up to a simple factor.

math-ph↗

arXiv2024

Quantum curves from refined topological recursion: the genus 0 case

We formulate geometrically (without reference to physical models) a refined topological recursion applicable to genus zero curves of degree two, inspired by Chekhov-Eynard and Marchal, introducing new degrees of freedom in the process. For such curves, we prove the fundamental properties of the recursion analogous to the unrefined case. We show the quantization of spectral curves due to Iwaki-Koike-Takei can be generalized to this setting and give the explicit formula, which turns out to be related to the unrefined case by a simple transformation. For an important collection of examples, we write down the quantum curves and find that in the Nekrasov-Shatashvili limit, they take an especially simple form.

math.AG↗

arXiv2023

Refined BPS structures and topological recursion - the Weber and Whittaker curves

We study properties of the recently established refined topological recursion for some simple spectral curves associated to quadratic differentials. We prove explicit formulas for the free energy and Voros coefficients of the corresponding quantum curves, and conjecture expressions for all other (smooth) genus zero degree two curves. The results can be written in terms of Bridgeland's notion of refined BPS structure associated to the same initial data, together with a quantum correction to the central charge. The corresponding "invariants" appear to be new, but their interpretation in terms of Donaldson-Thomas theory or QFT is not entirely clear.

math.AG↗

arXiv2020

Topological recursion and uncoupled BPS structures I: BPS spectrum and free energies

For the hypergeometric spectral curve and its confluent degenerations (spectral curves of "hypergeometric type"), we obtain a simple formula expressing the topological recursion free energies as a sum over BPS states (degenerate spectral networks) for a corresponding quadratic differential $φ$. In doing so, we generalize Gaiotto-Moore-Neitzke's construction of BPS structures to include the case where $φ$ has simple poles or supports a degenerate ring domain. For the nine spectral curves of hypergeometric type, we provide a complete description of the corresponding BPS structures over a generic locus in the relevant parameter space; in particular, we prove the existence of saddles trajectories at the expected parameter values. We determine the corresponding BPS cycles, central charges, and BPS invariants, and verify our formula in each case. We conjecture that a similar relation should hold more generally whenever the corresponding BPS structure is uncoupled, and provide experimental evidence in two simple higher rank examples.

math-ph↗

arXiv2017

Higher length-twist coordinates, generalized Heun's opers, and twisted superpotentials

In this paper we study a proposal of Nekrasov, Rosly and Shatashvili that describes the effective twisted superpotential obtained from a class S theory geometrically as a generating function in terms of certain complexified length-twist coordinates, and extend it to higher rank. First, we introduce a higher rank analogue of Fenchel-Nielsen type spectral networks in terms of a generalized Strebel condition. We find new systems of spectral coordinates through the abelianization method and argue that they are higher rank analogues of the Nekrasov-Rosly-Shatashvili Darboux coordinates. Second, we give an explicit parametrization of the locus of opers and determine the generating functions of this Lagrangian subvariety in terms of the higher rank Darboux coordinates in some specific examples. We find that the generating functions indeed agree with the known effective twisted superpotentials. Last, we relate the approach of Nekrasov, Rosly and Shatashvili to the approach using quantum periods via the exact WKB method.

hep-th↗