Publications

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• Candidate phases for SU(2) adjoint QCD$_4$ with two flavors from $\mathcal{N}=2$ supersymmetric Yang-Mills theory

  Clay Córdova, Thomas T. Dumitrescu

  SciPost Phys. 16, 139 (2024) · published 29 May 2024 | Toggle abstract · pdf

  We study four-dimensional adjoint QCD with gauge group $SU(2)$ and two Weyl fermion flavors, which has an $SU(2)_R$ chiral symmetry. The infrared behavior of this theory is not firmly established. We explore candidate infrared phases by embedding adjoint QCD into ${\mathcal N}=2$ supersymmetric Yang-Mills theory deformed by a supersymmetry-breaking scalar mass $M$ that preserves all global symmetries and 't Hooft anomalies. This includes 't Hooft anomalies that are only visible when the theory is placed on manifolds that do not admit a spin structure. The consistency of this procedure is guaranteed by a nonabelian spin-charge relation involving the $SU(2)_R$ symmetry that is familiar from topologically twisted ${\mathcal N}=2$ theories. Since every vacuum on the Coulomb branch of the ${\mathcal N}=2$ theory necessarily matches all 't Hooft anomalies, we can generate candidate phases for adjoint QCD by deforming the theories in these vacua while preserving all symmetries and 't Hooft anomalies. One such deformation is the supersymmetry-breaking scalar mass $M$ itself, which can be reliably analyzed when $M$ is small. In this regime it gives rise to an exotic Coulomb phase without chiral symmetry breaking. By contrast, the theory near the monopole and dyon points can be deformed to realize a candidate phase with monopole-induced confinement and chiral symmetry breaking. The low-energy theory consists of two copies of a $\mathbb{CP}^1$ sigma model, which we analyze in detail. Certain topological couplings that are likely to be present in this $\mathbb{CP}^1$ model turn the confining solitonic string of the model into a topological insulator. We also examine the behavior of various candidate phases under fermion mass deformations. We speculate on the possible large-$M$ behavior of the deformed ${\mathcal N}=2$ theory and conjecture that the $\mathbb{CP}^1$ phase eventually becomes dominant.

  1 citation

• Boundary conditions for extremal black holes from 2d gravity

  Stephane Detournay, Thomas Smoes, Raphaela Wutte

  SciPost Phys. 16, 141 (2024) · published 30 May 2024 | Toggle abstract · pdf

  We devise new boundary conditions for the near-horizon geometries of extremal BTZ and Kerr black holes, as well as for the ultra-cold limit of the Kerr-de Sitter black hole. These boundary conditions are obtained as the higher-dimensional uplift of recently proposed boundary conditions in two-dimensional gravity. Their asymptotic symmetries consist in the semi-direct product of a Virasoro and a current algebra, of which we determine the central extensions.

  1 citation

• Asymptotic structure of higher dimensional Yang-Mills theory

  Temple He, Prahar Mitra

  SciPost Phys. 16, 142 (2024) · published 30 May 2024 | Toggle abstract · pdf

  Using the covariant phase space formalism, we construct the phase space for non-Abelian gauge theories in (d+2)-dimensional Minkowski spacetime for any d ≥ 2, including the edge modes that symplectically pair to the low energy degrees of freedom of the gauge field. Despite the fact that the symplectic form in odd and even-dimensional spacetimes appear ostensibly different, we demonstrate that both cases can be treated in a unified manner by utilizing the shadow transform. Upon quantization, we recover the algebra of the vacuum sector of the Hilbert space and derive a Ward identity that implies the leading soft gluon theorem in (d+2)-dimensional spacetime.

  1 citation

• One-shot holography

  Chris Akers, Adam Levine, Geoff Penington, Elizabeth Wildenhain

  SciPost Phys. 16, 144 (2024) · published 4 June 2024 | Toggle abstract · pdf

  Following the work of [J. High Energy Phys. 04, 062 (2021)], we define a generally covariant max-entanglement wedge of a boundary region B, which we conjecture to be the bulk region reconstructible from B. We similarly define a covariant min-entanglement wedge, which we conjecture to be the bulk region that can influence the state on B. We prove that the min- and max-entanglement wedges obey various properties necessary for this conjecture, such as nesting, inclusion of the causal wedge, and a reduction to the usual quantum extremal surface prescription in the appropriate special cases. These proofs rely on one-shot versions of the (restricted) quantum focusing conjecture (QFC) that we conjecture to hold. We argue that these QFCs imply a one-shot generalized second law (GSL) and quantum Bousso bound. Moreover, in a particular semiclassical limit we prove this one-shot GSL directly using algebraic techniques. Finally, in order to derive our results, we extend both the frameworks of one-shot quantum Shannon theory and state-specific reconstruction to finite-dimensional von Neumann algebras, allowing nontrivial centers.

  1 citation

• Off-shell strings I: S-matrix and action

  Amr Ahmadain, Aron C. Wall

  SciPost Phys. 17, 005 (2024) · published 5 July 2024 | Toggle abstract · pdf

  We explain why Tseytlin's off-shell formulation of string theory is well-defined. Although quantizing strings on an off-shell background requires an arbitrary choice of Weyl frame, this choice is not physically significant since it can be absorbed into a field redefinition of the target space fields. The off-shell formalism is particularly subtle at tree-level, due to the treatment of the noncompact conformal Killing group SL(2,$\mathbb{C}$) of the sphere. We prove that Tseytlin's sphere prescriptions recover the standard tree-level Lorentzian S-matrix, and show how to extract the stringy $i\varepsilon$ prescription from the UV cutoff on the worldsheet. We also demonstrate that the correct tree-level equations of motion are obtained to all orders in perturbation theory in $g_s$ and $\alpha^{\prime}$, and illuminate the close connection between the string action and the c-theorem.

  1 citation

• Off-shell strings II: Black hole entropy

  Amr Ahmadain, Aron C. Wall

  SciPost Phys. 17, 006 (2024) · published 5 July 2024 | Toggle abstract · pdf

  In 1994, Susskind and Uglum argued that it is possible to derive the Bekenstein-Hawking entropy $A/4G_N$ from string theory. In this article we explain the conceptual underpinnings of this argument, while elucidating its relationship to induced gravity and ER=EPR. Following an off-shell calculation by Tseytlin, we explicitly derive the classical closed string effective action from sphere diagrams at leading order in $\alpha^{\prime}$. We then show how to use this to obtain black hole entropy from the RG flow of the NLSM on conical manifolds. (We also briefly discuss the more problematic "open string picture" of Susskind and Uglum, in which strings end on the horizon.) We then compare these off-shell results with the rival "orbifold replica trick" using the on-shell $\mathbb{C}/Z_{N}$ background, which does not account for the leading order Bekenstein-Hawking entropy-unless perhaps tachyons are allowed to condense on the orbifold. Possible connections to the ER=EPR conjecture are explored. Finally, we discuss prospects for various extensions, including prospects for deriving holographic entanglement entropy in the bulk of AdS.

  1 citation

• Decorated defect construction of gapless-SPT states

  Linhao Li, Masaki Oshikawa, Yunqin Zheng

  SciPost Phys. 17, 013 (2024) · published 15 July 2024 | Toggle abstract · pdf

  Symmetry protected topological (SPT) phases are one of the simplest, yet nontrivial, gapped systems that go beyond the Landau paradigm. In this work, we study an extension of the notion of SPT for gapless systems, namely, gapless symmetry protected topological states. We construct several simple gapless-SPT models using the decorated defect construction, which allow analytical understanding of non-trivial topological features including the symmetry charge under twisted boundary conditions, and boundary (quasi)-degeneracy under open boundary conditions. We also comment on the stability of the gapless-SPT models under symmetric perturbations, and apply small-scale exact diagonalization when direct analytic understanding is not available.

  1 citation

• Vortex loop operators and quantum M2-branes

  Nadav Drukker, Omar Shahpo

  SciPost Phys. 17, 016 (2024) · published 16 July 2024 | Toggle abstract · pdf

  We study M2-branes in $AdS_4× S^7/\mathbb{Z}_k$ dual to 1/2 and 1/3 BPS vortex loop operators in ABJM theory and compute their one-loop correction beyond the classical M2-brane action. The correction depends only on the parity of $k$ and is independent of all continuous parameters in the definition of the vortex loops. The result for odd $k$ agrees with the answers for the 1/2 BPS Wilson loop in the $k=1$ theory and for even $k$ with the one in the $k = 2$ theory. Combining with the classical part, we find that the natural expansion parameter seems to be $1/\sqrt{kN}$ rather than $1/\sqrt{N}$. This provides a further setting where semiclassical quantisation can be applied to M2-branes and produces new results inaccessible by other methods.

  1 citation

• The $g$-function and defect changing operators from wavefunction overlap on a fuzzy sphere

  Zheng Zhou, Davide Gaiotto, Yin-Chen He, Yijian Zou

  SciPost Phys. 17, 021 (2024) · published 25 July 2024 | Toggle abstract · pdf

  Defects are common in physical systems with boundaries, impurities or extensive measurements. The interaction between bulk and defect can lead to rich physical phenomena. Defects in gapless phases of matter with conformal symmetry usually flow to a defect conformal field theory (dCFT). Understanding the universal properties of dCFTs is a challenging task. In this paper, we propose a computational strategy applicable to a line defect in arbitrary dimensions. Our main assumption is that the defect has a UV description in terms of a local modification of the Hamiltonian so that we can compute the overlap between low-energy eigenstates of a system with or without the defect insertion. We argue that these overlaps contain a wealth of conformal data, including the $g$-function, which is an RG monotonic quantity that distinguishes different dCFTs, the scaling dimensions of defect creation operators $\Delta^{+0}_\alpha$ and changing operators $\Delta^{+-}_\alpha$ that live on the intersection of different types of line defects, and various OPE coefficients. We apply this method to the fuzzy sphere regularization of 3D CFTs and study the magnetic line defect of the 3D Ising CFT. Using exact diagonalization and DMRG, we report the non-perturbative results $g=0.602(2),\Delta^{+0}_0=0.108(5)$ and $\Delta^{+-}_0=0.84(5)$ for the first time. We also obtain other OPE coefficients and scaling dimensions. Our results have significant physical implications. For example, they constrain the possible occurrence of spontaneous symmetry breaking at line defects of the 3D Ising CFT. Our method can be potentially applied to various other dCFTs, such as plane defects and Wilson lines in gauge theories.

  1 citation

• Central exclusive production of axial-vector f1 mesons in proton-proton collisions within the tensor-pomeron approach

  Piotr Lebiedowicz

  SciPost Phys. Proc. 6, 010 (2022) · published 31 May 2022 | Toggle abstract · pdf

  We discuss the central exclusive production of $f_{1}$ mesons in proton-proton collisions. The diffractive pomeron-pomeron fusion process within the tensor-pomeron approach is considered. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are discussed. The theoretical calculation of coupling constants is a challenging problem of nonperturbative QCD. We adjust the parameters of the model to the WA102 experimental data. The total cross section and differential distributions are presented. Predictions for LHC experiments are given. Detailed analysis of the distributions in $\phi_{pp}$ the azimuthal angle between the transverse momenta of the outgoing protons can help to check different models and to study real pattern of the absorption effects.

  1 citation