Recent zbMATH articles in MSC 81T50https://www.zbmath.org/atom/cc/81T502021-04-16T16:22:00+00:00WerkzeugString defects, supersymmetry and the Swampland.https://www.zbmath.org/1456.830862021-04-16T16:22:00+00:00"Angelantonj, Carlo"https://www.zbmath.org/authors/?q=ai:angelantonj.carlo"Bonnefoy, Quentin"https://www.zbmath.org/authors/?q=ai:bonnefoy.quentin"Condeescu, Cezar"https://www.zbmath.org/authors/?q=ai:condeescu.cezar"Dudas, Emilian"https://www.zbmath.org/authors/?q=ai:dudas.emilianSummary: Recently, Kim, Shiu and Vafa proposed general consistency conditions for six dimensional supergravity theories with minimal supersymmetry coming from couplings to strings. We test them in explicit perturbative orientifold models in order to unravel the microscopic origin of these constraints. Based on the perturbative data, we conjecture the existence of null charges \(Q \bullet Q = 0\) for any six-dimensional theory with at least one tensor multiplet, coupling to string defects of charge \(Q\). We then include the new constraint to exclude some six-dimensional supersymmetric anomaly-free examples that have currently no string or F-theory realization. We also investigate the constraints from the couplings to string defects in case where supersymmetry is broken in tachyon free vacua, containing non-BPS configurations of brane supersymmetry breaking type, where the breaking is localized on antibranes. In this case, some conditions have naturally to be changed or relaxed whenever the string defects experience supersymmetry breaking, whereas the constraints are still valid if they are geometrically separated from the supersymmetry breaking source.Secularly growing loop corrections in scalar wave background.https://www.zbmath.org/1456.813142021-04-16T16:22:00+00:00"Akhmedov, E. T."https://www.zbmath.org/authors/?q=ai:akhmedov.emil-t"Diatlyk, O."https://www.zbmath.org/authors/?q=ai:diatlyk.o-nSummary: We consider two-dimensional Yukawa theory in the scalar wave background \(\varphi (t-x)\). If one takes as initial state in such a background the scalar vacuum corresponding to \(\varphi = 0\), then loop corrections to a certain part of the Keldysh propagator, corresponding to the anomalous expectation value, grow with time. That is a signal to the fact that under the kick of the \(\varphi (t-x)\) wave the scalar field rolls down the effective potential from the \(\varphi = 0\) position to the proper ground state. We show the evidence supporting these observations.Anomalous dimensions from thermal AdS partition functions.https://www.zbmath.org/1456.814132021-04-16T16:22:00+00:00"Kraus, Per"https://www.zbmath.org/authors/?q=ai:kraus.per"Megas, Stathis"https://www.zbmath.org/authors/?q=ai:megas.stathis"Sivaramakrishnan, Allic"https://www.zbmath.org/authors/?q=ai:sivaramakrishnan.allicSummary: We develop an efficient method for computing thermal partition functions of weakly coupled scalar fields in AdS. We consider quartic contact interactions and show how to evaluate the relevant two-loop vacuum diagrams without performing any explicit AdS integration, the key step being the use of Källén-Lehmann type identities. This leads to a simple method for extracting double-trace anomalous dimensions in any spacetime dimension, recovering known first-order results in a streamlined fashion.Dynamic scale anomalous transport in QCD with electromagnetic background.https://www.zbmath.org/1456.814122021-04-16T16:22:00+00:00"Kawaguchi, Mamiya"https://www.zbmath.org/authors/?q=ai:kawaguchi.mamiya"Matsuzaki, Shinya"https://www.zbmath.org/authors/?q=ai:matsuzaki.shinya"Huang, Xu-Guang"https://www.zbmath.org/authors/?q=ai:huang.xu-guangSummary: We discuss phenomenological implications of the anomalous transport induced by the scale anomaly in QCD coupled to an electromagnetic (EM) field, based on a dilaton effective theory. The scale anomalous current emerges in a way perfectly analogous to the conformal transport current induced in a curved spacetime background, or the Nernst current in Dirac and Weyl semimetals --- both current forms are equivalent by a ``Weyl transformation''. We focus on a spatially homogeneous system of QCD hadron phase, which is expected to be created after the QCD phase transition and thermalization. We find that the EM field can induce a dynamic oscillatory dilaton field which in turn induces the scale anomalous current. As the phenomenological applications, we evaluate the dilepton and diphoton productions induced from the dynamic scale anomalous current, and find that those productions include a characteristic peak structure related to the dynamic oscillatory dilaton, which could be tested in heavy ion collisions. We also briefly discuss the out-of-equilibrium particle production created by a nonadiabatic dilaton oscillation, which happens in a way of the so-called tachyonic preheating mechanism.Interface conformal anomalies.https://www.zbmath.org/1456.813822021-04-16T16:22:00+00:00"Herzog, Christopher P."https://www.zbmath.org/authors/?q=ai:herzog.christopher-p"Huang, Kuo-Wei"https://www.zbmath.org/authors/?q=ai:huang.kuo-wei"Vassilevich, Dmitri V."https://www.zbmath.org/authors/?q=ai:vassilevich.dmitri-vSummary: We consider two \(d \geq 2\) conformal field theories (CFTs) glued together along a codimension one conformal interface. The conformal anomaly of such a system contains both bulk and interface contributions. In a curved-space setup, we compute the heat kernel coefficients and interface central charges in free theories. The results are consistent with the known boundary CFT data via the folding trick. In \(d = 4\), two interface invariants generally allowed as anomalies turn out to have vanishing interface charges. These missing invariants are constructed from components with odd parity with respect to flipping the orientation of the defect. We conjecture that all invariants constructed from components with odd parity may have vanishing coefficient for symmetric interfaces, even in the case of interacting interface CFT.Emergent Yang-Mills theory.https://www.zbmath.org/1456.830202021-04-16T16:22:00+00:00"de Mello Koch, Robert"https://www.zbmath.org/authors/?q=ai:de-mello-koch.robert"Huang, Jia-Hui"https://www.zbmath.org/authors/?q=ai:huang.jiahui"Kim, Minkyoo"https://www.zbmath.org/authors/?q=ai:kim.minkyoo"Van Zyl, Hendrik J. R."https://www.zbmath.org/authors/?q=ai:van-zyl.hendrik-j-rSummary: We study the spectrum of anomalous dimensions of operators dual to giant graviton branes. The operators considered belong to the \(\mathrm{su} (2|3)\) sector of \(\mathcal{N} = 4\) super Yang-Mills theory, have a bare dimension \(\sim N\) and are a linear combination of restricted Schur polynomials with \(p \sim O(1)\) long rows or columns. In the same way that the operator mixing problem in the planar limit can be mapped to an integrable spin chain, we find that our problems maps to particles hopping on a lattice. The detailed form of the model is in precise agreement with the expected world volume dynamics of \(p\) giant graviton branes, which is a \(\mathrm{U} (p)\) Yang-Mills theory. The lattice model we find has a number of noteworthy features. It is a lattice model with all-to-all sites interactions and quenched disorder.Global aspects of spaces of vacua.https://www.zbmath.org/1456.831082021-04-16T16:22:00+00:00"Sharon, Adar"https://www.zbmath.org/authors/?q=ai:sharon.adarSummary: We study ``vacuum crossing'', which occurs when the vacua of a theory are exchanged as we vary some periodic parameter \(\theta\) in a closed loop. We show that vacuum crossing is a useful non-perturbative tool to study strongly-coupled quantum field theories, since finding vacuum crossing in a weakly-coupled regime of the theory can lead to nontrivial consequences in the strongly-coupled regime. We start by discussing a mechanism where vacuum crossing occurs due to an anomaly, and then discuss some applications of vacuum crossing in general. In particular, we argue that vacuum crossing can be used to check IR dualities and to look for emergent IR symmetries.The unique Polyakov blocks.https://www.zbmath.org/1456.814032021-04-16T16:22:00+00:00"Sleight, Charlotte"https://www.zbmath.org/authors/?q=ai:sleight.charlotte"Taronna, Massimo"https://www.zbmath.org/authors/?q=ai:taronna.massimoSummary: In this work we present a closed form expression for Polyakov blocks in Mellin space for arbitrary spin and scaling dimensions. We provide a prescription to fix the contact term ambiguity uniquely by reducing the problem to that of fixing the contact term ambiguity at the level of cyclic exchange amplitudes --- defining cyclic Polyakov blocks --- in terms of which any fully crossing symmetric correlator can be decomposed. We also give another, equivalent, prescription which does not rely on a decomposition into cyclic amplitudes. We extract the OPE data of double-twist operators in the direct channel expansion of the cyclic Polyakov blocks using and extending the analysis of [\textit{C. Sleight} and \textit{M. Taronna}, J. High Energy Phys. 2018, No. 11, Paper No. 89, 62 p. (2018; Zbl 1404.81242)] to include contributions that are non-analytic in spin. The relation between cyclic Polyakov blocks and analytic Bootstrap functionals is underlined.\( \mathrm{SL}(2,\mathbb{Z})\) action on QFTs with \(\mathbb{Z}_2\) symmetry and the Brown-Kervaire invariants.https://www.zbmath.org/1456.814052021-04-16T16:22:00+00:00"Bhardwaj, Lakshya"https://www.zbmath.org/authors/?q=ai:bhardwaj.lakshya"Lee, Yasunori"https://www.zbmath.org/authors/?q=ai:lee.yasunori"Tachikawa, Yuji"https://www.zbmath.org/authors/?q=ai:tachikawa.yujiSummary: We consider an analogue of Witten's \( \mathrm{SL}(2,\mathbb{Z})\) action on three-dimensional QFTs with U(1) symmetry for \(2k\)-dimensional QFTs with \(\mathbb{Z}_2\) \( (k-1) \)-form symmetry. We show that the \( \mathrm{SL}(2,\mathbb{Z})\) action only closes up to a multiplication by an invertible topological phase whose partition function is the Brown-Kervaire invariant of the spacetime manifold. We interpret it as part of the \( \mathrm{SL}(2,\mathbb{Z})\) anomaly of the bulk \((2k + 1)\)-dimensional \(\mathbb{Z}_2\) gauge theory.The UV fate of anomalous U(1)s and the Swampland.https://www.zbmath.org/1456.830952021-04-16T16:22:00+00:00"Craig, Nathaniel"https://www.zbmath.org/authors/?q=ai:craig.nathaniel"Garcia, Isabel Garcia"https://www.zbmath.org/authors/?q=ai:garcia-garcia.isabel"Kribs, Graham D."https://www.zbmath.org/authors/?q=ai:kribs.graham-dSummary: Massive U(1) gauge theories featuring parametrically light vectors are suspected to belong in the Swampland of consistent EFTs that cannot be embedded into a theory of quantum gravity. We study four-dimensional, chiral U(1) gauge theories that appear anomalous over a range of energies up to the scale of anomaly-cancelling massive chiral fermions. We show that such theories must be UV-completed at a finite cutoff below which a radial mode must appear, and cannot be decoupled --- a Stückelberg limit does not exist. When the infrared fermion spectrum contains a mixed U(1)-gravitational anomaly, this class of theories provides a toy model of a boundary into the Swampland, for sufficiently small values of the vector mass. In this context, we show that the limit of a parametrically light vector comes at the cost of a quantum gravity scale that lies parametrically below \(M_{ \mathrm{Pl}}\), and our result provides field theoretic evidence for the existence of a Swampland of EFTs that is disconnected from the subset of theories compatible with a gravitational UV-completion. Moreover, when the low energy theory also contains a \( \mathrm{U}(1)^3\) anomaly, the Weak Gravity Conjecture scale makes an appearance in the form of a quantum gravity cutoff for values of the gauge coupling above a certain critical size.