arXiv subjects

Ziwen Kong

Publications and source records attributed to Ziwen Kong.

11 recordsLinked to original sources

arXiv2025

Nonlinearly Realised Defect Symmetries and Anomalies

Conformal defects -- extended objects in conformal field theories -- carry localised excitations inherited from symmetry currents, known as the displacements and tilts. They capture the linear response of the defect to deformations of its shape or of its profile along internal symmetry directions. There is no universal formula for deformations beyond the linear order and this is subject to ambiguities of coordinate choices on coset spaces and scheme dependence in the quantum theory. We analyse the exact match between the two and identify the scheme independent quantities capturing nonlinearly realised symmetries. This leads to universal integral identities for correlation functions in the presence of tilts and displacements. We present several applications of them. We also study possible anomalies, recovering known ones, finding new expressions for them, and uncovering new ones.

hep-th↗

arXiv2025

There and Back Again: Bulk-to-Defect via Ward Identities

In conformal field theory, the presence of a defect may break the global symmetry, giving rise to defect operators such as the tilts. In this work, we derive integral identities that relate correlation functions involving bulk and defect operators -- including tilts -- to lower-point bulk-defect correlators, based on a detailed analysis of the Lie algebra of the symmetry group before and after the defect-induced symmetry breaking. As explicit examples, we illustrate these identities for the 1/2 BPS Maldacena-Wilson loop in $\mathcal{N}=4$ SYM and for magnetic lines in the $O(N)$ model in $d=4-\varepsilon$ dimensions. We demonstrate that these identities provide a powerful tool both to check existing perturbative correlators and to impose nontrivial constraints on the CFT data.

hep-th↗

arXiv2025

Integral Identities from Symmetry Breaking of Conformal Defects

In conformal field theory, the insertion of a defect breaks part of the global symmetry and gives rise to defect operators such as the tilts and displacements. We establish identities relating the integrated four-point functions of such operators to their two-point functions, derived both from the geometric properties of the defect conformal manifold, which is the symmetry-breaking coset, and from the Lie algebra of the corresponding broken symmetry generators. As an explicit example, we demonstrate these integral identities in the case of the 1/2 BPS Maldacena-Wilson loop in $\mathcal{N} = 4$ SYM. This contribution serves as a brief review of the main ideas of Phys. Rev. Lett. 129, 201603 (2022), as well as a short preview of our forthcoming paper with Nadav Drukker and Petr Kravchuk. Here we present an independent derivation of the integral identities that will not appear in that work.

hep-th↗

arXiv2025

Fine Spectrum from Crude Analytic Bootstrap

The magnetic line defect in the $O(N)$ model gives rise to a non-trivial one-dimensional defect conformal field theory of theoretical and experimental value. This model is considered here in $d=4-\varepsilon$ and the full spectrum of defect operators with dimensions close to one, two and three at order $\varepsilon$ is presented. The spectrum of several classes of operators of dimension close to four and operators of large charge are also discussed. Analytic bootstrap techniques are used extensively, and efficient tools to deal with the unmixing of nearly degenerate operators are developed. Integral identities are also incorporated, and it is shown that they lead to constraints on some three-point function coefficients and anomalous dimensions to order $\varepsilon^2$.

hep-th↗

arXiv2025

Long-range to the Rescue of Yang-Baxter II

We study the spin chain model capturing the one-loop spectral problem of the simplest $\mathcal{N}=2$ superconformal quiver gauge theory in four dimensions, obtained from a marginal deformation of the $\mathbb{Z}_2$ orbifold of $\mathcal{N}=4$ SYM. In Part I of this work \cite{Bozkurt:2024tpz}, we solved for the three-magnon eigenvector and found that it exhibits long-range behavior, despite the Hamiltonian being of nearest-neighbor type. In this paper, we extend the analysis to the four-magnon sector and construct explicit eigenvectors. These solutions are compatible with both untwisted and twisted periodic boundary conditions, and they allow for the computation of anomalous dimensions of single-trace operators of the gauge theory. We validate our results by direct comparison with brute-force diagonalization of the spin chain Hamiltonian. Additionally, we uncover a novel structural relation between eigenstates with different numbers of excitations. In particular, we show that the four-magnon eigenstates can be written in terms of the three-magnon solution, revealing a recursive pattern and hinting at a deeper underlying structure. Lastly, the four-magnon solution obeys an infinite tower of Yang-Baxter equations, as was the case for the three-magnon solution.

hep-th↗

arXiv2023

1/3 BPS loops and defect CFTs in ABJM theory

We address a longstanding question of whether ABJM theory has Wilson loop operators preserving eight supercharges (so 1/3 BPS). We present such Wilson loops made of a large supermatrix combining two 1/2 BPS Wilson loops. We study the spectrum of operator insertions into them including the displacement operator and several others and study their correlation functions. Another natural construction arising in this context are Wilson loops with alternating superconnections. This amounts to including "defect changing operators" along the loop, similar to a discrete cusp. This insertion is topological and preserves two supercharges. We study the multiplet of this operator and how it can be used to introduce further operators. We also construct the defect conformal manifold arising from marginal defect operators.

hep-th↗

arXiv2023

The planar limit of integrated 4-point functions

We compute the planar limit, as all-order power series in the 't Hooft coupling, of various integrated 4-point functions of chiral primary operators of ${\cal N}=4$ SU(N) super Yang-Mills, and of moment map operators of ${\cal N}=2$ SU(N) SQCD. We do so by computing the planar free energy on $S^4$ of the respective massive deformations of these theories, and then taking advantage of the exact relation between these free energies and the integrated 4-point functions.

hep-th↗

arXiv2022

A network of hyperloops

In this paper we complete the exploration of connected components of the space of BPS Wilson loops in three-dimensional $\mathcal{N}=4$ Chern-Simons-matter theory on $S^3$. The algorithm is to start with a supersymmetric Wilson loop, choose a preserved supercharge, and look for BPS deformations built out of the matter fields in the proper representations. Using this, we discover many new moduli spaces of nonconformal BPS Wilson loops preserving a single or two supercharges, which are subsets of the symmetries of the 1/4 and 3/8 BPS operators. Along with the those previously found in arXiv:2012.07096, arXiv:2206.07390 and arXiv:2210.03758, the total moduli spaces are closed under this formalism.

hep-th↗

arXiv2022

Classifying BPS bosonic Wilson loops in 3d ${\cal N}=4$ Chern-Simons-matter theories

We study the possible BPS Wilson loops in three-dimensional ${\cal N}=4$ Chern-Simons-matter theory which involve only the gauge field and bilinears of the scalars. Previously known examples are the analogues of the Gaiotto-Yin loops preserving four supercharges and "latitude" loops preserving two. We carry out a careful classification and find, in addition, loops preserving three supercharges, further inequivalent classes of loops preserving two supercharges and loops preserving a single supercharge. For each of the classes of loops, we present a representative example and analyse their full orbit under the broken symmetries.

hep-th↗

arXiv2022

Broken global symmetries and defect conformal manifolds

Just as exactly marginal operators allow to deform a conformal field theory along the space of theories known as the conformal manifold, appropriate operators on conformal defects allow for deformations of the defects. When a defect breaks a global symmetry, there is a contact term in the conservation equation with an exactly marginal defect operator. The resulting defect conformal manifold is the symmetry breaking coset and its Zamolodchikov metric is expressed as the 2-point function of the exactly marginal operator. As the Riemann tensor on the conformal manifold can be expressed as an integrated 4-point function of the marginal operators, we find an exact relation to the curvature of the coset space. We confirm this relation against previously obtained 4-point functions for insertions into the 1/2 BPS Wilson loop in ${\cal N} = 4$ SYM and 3d ${\cal N} = 6$ theory and the 1/2 BPS surface operator of the 6d ${\cal N} = (2, 0)$ theory.

hep-th↗

arXiv2022

Conformal and non-conformal hyperloop deformations of the 1/2 BPS circle

We construct new large classes of BPS Wilson hyperloops in three-dimensional ${\cal N}=4$ quiver Chern-Simons-matter theory on $S^3$. The main strategy is to start with the 1/2 BPS Wilson loop of this theory, choose any linear combination of the supercharges it preserves, and look for deformations built out of the matter fields that still preserve that supercharge. This is a powerful generalization of a recently developed approach based on deformations of 1/4 and 1/8 BPS bosonic loops, which itself was far more effective at discovering new operators than older methods relying on complicated ansatze. We discover many new moduli spaces of BPS hyperloops preserving varied numbers of supersymmetries and varied subsets of the symmetries of the 1/2 BPS operator. In particular, we find new bosonic operators preserving 2 or 3 supercharges as well as new families of loops that do not share supercharges with any bosonic loops, including subclasses of both 1/8 and 1/4 BPS loops that are conformal.

hep-th↗