4d/2d -> 3d/1d: A song of protected operator algebras

Superconformal field theories (SCFT) are known to possess solvable yet nontrivial sectors in their full operator algebras. Two prime examples are the chiral algebra sector on a two dimensional plane in four dimensional N=2 SCFTs, and the topological quantum mechanics (TQM) sector on a line in three dimensional N=4 SCFTs. Under Weyl transformation, they respectively map to operator algebras on a great torus in S^1×S^3 and a great circle in S^3, and are naturally related by reduction along the S^1 factor, which amounts to taking the Cardy (high-temperature) limit of the four dimensional theory on S1×S3. We elaborate on this relation by explicit examples that involve both Lagrangian and non-Lagrangian theories in four dimensions, where the chiral algebra sector is generally described by a certain W-algebra, while the three dimensional descendant SCFT always has a (mirror) Lagrangian description. By taking into account a subtle R-symmetry mixing, we provide explicit dictionaries between selected operator product expansion (OPE) data in the four and three dimensional SCFTs, which we verify in the examples using recent localization results in four and three dimensions. Our methods thus provide nontrivial support for various chiral algebra proposals in the literature. Along the way, we also identify three dimensional mirrors for Argyres-Douglas theories of type (A1,D2n+1) reduced on S^1, and find more evidence for earlier proposals in the case of (A_1,A_(2n−2)), which both realize certain superconformal boundary conditions for the four dimensional N=4 super-Yang-Mills. This is a companion paper to arXiv:1911.05741

Constraining Higher Derivative Supergravity with Scattering Amplitudes

We study supersymmetry constraints on higher derivative deformations of type IIB supergravity by consideration of superamplitudes. Combining constraints of on-shell supervertices and basic results from string perturbation theory, we give a simple argument for the non-renormalization theorem of Green and Sethi, and some of its generalizations.Comment: 9 pages, 2 figures; references ad

Classification of Argyres-Douglas theories from M5 branes

We obtain a large class of new 4d Argyres-Douglas theories by classifying irregular punctures for the 6d (2,0) superconformal theory of ADE type on a sphere. Along the way, we identify the connection between the Hitchin system and three-fold singularity descriptions of the same Argyres-Douglas theory. Other constructions such as taking degeneration limits of the irregular puncture, adding an extra regular puncture, and introducing outer-automorphism twists are also discussed. Later we investigate various features of these theories including their Coulomb branch spectrum and central charges.Comment: 35 pages, 9 tables, 6 figures. v2: minor correction

Comments on the twisted punctures of AevenA_\text{even} class S theory

We point out that the $\text{USp}$ symmetry associated to a full twisted puncture of a class S theory of type $A_\text{even}$ has the global anomaly associated to $\pi_4(\text{USp})=\mathbb{Z}_2$. We discuss manifestations of this fact in the context of the superconformal field theory $R_{2,2N}$ introduced by Chacaltana, Distler and Trimm. For example, we find that this theory can be thought of as a natural ultraviolet completion of an infrared-free $\text{SO}(2N+1)$ gauge theory with $2N$ flavors, whose $\text{USp}(4N)$ symmetry clearly has the global anomaly.Comment: 14 pages, 5 figures; v2: minor change