M-theory singularities: Going beyond Dynkin diagrams

• Andres Collinucci (Université Libre de Bruxelles)

Room: 4/3-006 - TH Conference Room M-theory on an ADE singularity gives rise to an ADE gauge theory at low energies. However, the “T-brane” phenomenon completely shatters this picture, and reveals that simply resolving singularities, and uncovering a Dynkin diagram is insufficient to understand what’s really going on. I will demonstrate how exploiting 3d mirror symmetry sheds light on T-branes, and gives us a new definition of the phenomenon for all ADE algebras. For the E-series, we will see how non-Lagrangian theories actually simplify the problem.

Discussion Room: 4/3-006 - TH Conference Room

Singularities and F-theory

• Antonella Grassi (University of Pennsylvania)

Room: 4/3-006 - TH Conference Room I will review background results and discuss recent progress.

Discussion Room: 4/3-006 - TH Conference Room

5d SCFTs and their gauge theory phases

• Michele del Zotto (Durham University)

Room: 4/3-006 - TH Conference Room In this talk I will revist the geometric engineering of five-dimensional supersymmetric conformal field theories (SCFTs) in M-theory after Intrilligator, Morrison and Seiberg. This esablishes a conjectural map assigning to each local isolated Calabi-Yau three-fold singularity a five-dimensional superconformal field theory. Focusing on the toric case, I will discuss applications of IIA/M-theory fiberwise duality to characterizing the possible gauge theory phases of these systems. This geometric setup clarifies the notion of “UV duality” for such theories. Along the way, I will provide a slightly revised gauge theoretical expression for the 5d prepotential, accounting correctly for the 5d parity anomaly. Based on the preprint arXiv:1812.10451, with Cyril Closset and Vivek Saxena.

Discussion Room: 4/3-006 - TH Conference Room

G2 and String Dualities

• Andreas Braun (University of Oxford)

Room: 4/3-006 - TH Conference Room I will discuss how G2 manifolds appearing in various dualities between string theories and M/F-Theory may be constructed and analysed, and give numerous examples of such instances. The proposed duals may then be used to learn about G2 geometry and establish the existence of singular limits interesting for M-Theory model building.

Discussion Room: 4/3-006 - TH Conference Room

New G2 conifolds in M theory and their Gauge Theory Interpretations

• Bobby Acharya (ICTP Trieste and King's College London)

Room: 4/3-006 - TH Conference Room I will report on recent work with L. Foscolo, M. Najjar and E. Svanes on the physics of recently constructed G2-holonomy spaces. These are all constructed as circle bundles over hyperconifolds and their resolutions and can be interpreted as Type IIA Calabi-Yau backgrounds with fluxes. We describe a correspondence between such G2-manifolds and vacua of 7D super Yang-Mills theories on Lens spaces, leading to a type of gauge/gravity duality in $M$ theory. We make some conjectures concerning the quantum moduli spaces of these vacua.

Discussion Room: 4/3-006 - TH Conference Room

The Swampland, Moduli and Holography

• Joe Conlon (University of Oxford)

Room: 4/3-006 - TH Conference Room String compactifications are essential for connecting string theory to low energy particle physics and cosmology. Moduli stabilisation gives rise to effective Lagrangians that capture the low-energy degrees of freedom. Much recent interest has been on swampland consistency conditions on such effective field theories - which low energy Lagrangians can arise from quantum gravity? How are moduli Lagrangians constrained by consistency with quantum gravity? As moduli stabilisation scenarios often exist in AdS space, we can also ask: what do swampland conditions mean in the context of AdS/CFT? Focussing in particular on the Large Volume Scenario, I describe work towards developing a holographic understanding of moduli stabilisation and swampland consistency conditions.

High charges in M-theory and F-theory

• Roberto Valandro (ICTP Trieste & INFN)

Room: 4/3-006 - TH Conference Room We present a constructive approach to M-theory and F-theory models with a U(1) gauge group and hypermultiplets with different charges. The three-folds are ALE fibrations over a (complex) one dimensional space; we combine the hyperkaehler structure of the ALE fiber with the algebraic description of the total space in terms of quivers.

Discussion Room: 4/3-006 - TH Conference Room

Moduli for generic N=1 flux backgrounds

• Dan Waldram (Imperial College)

Room: 4/3-006 - TH Conference Room We’ll discuss how to characterise generic four-dimensional N=1 backgrounds in supergravity using generalised geometry. We find that there is a natural generalised cohomology, a sort of extension of Dolbeault cohomology, that can be used to count the moduli of the compactification. We show how this works in a some simple examples.

Discussion Room: 4/3-006 - TH Conference Room

Comments on F-theory/heterotic duality in 8 dimensions

• Anamaria Font (Universidad Central de Venezuela)

Room: 4/3-006 - TH Conference Room

Discussion Room: 4/3-006 - TH Conference Room

Phases of little string theory and fuzzballs

• Stefano Massai (University of Chicago)

Room: 4/3-006 - TH Conference Room Resolved A-type singularities admit an exact description in worldsheet string theory that regularises the linear dilaton throat dual to little string theory. A generalisation of this mechanism offers a weakly coupled description of “fuzzball” states in the Hilbert space of two and three-charge black holes. These constructions reveal stringy excitations that become light at the threshold of horizon formation and provide a glimpse of the entropic long string sector in the gravity regime. A unifying twelve dimensional description of black hole microstates emerges.

Discussion Room: 4/3-006 - TH Conference Room

Unification of Symmetries from Strings

• Patrick Vaudrevange (TU Munich)

Room: 4/3-006 - TH Conference Room String Theory in 4D is highly predictive due to the compactification of extra dimensions: specifying a set of abstract compactification parameters, the particle content, all symmetries and all interactions in the effective low-energy theory are uniquely fixed. This is in contrast to Quantum Field Theory: the effective Lagrangian from String Theory cannot be altered at will, i.e. no particles, symmetries or interactions can be added or removed by hand. Moreover, modular symmetries are a genuine stringy effect which can yield important consequences for the 4D effective theory. In this respect, we will discuss the unification of flavor symmetries, modular symmetries and CP from String Theory.

Discussion Room: 4/3-006 - TH Conference Room

SU(3) structures on Calabi-Yau manifolds

• Magdalena Larfors (Uppsala University)

Room: 4/3-006 - TH Conference Room In this talk, we show that a range of non-trivial SU(3) structures can be constructed on complete intersection Calabi-Yau three-folds. Among the possible SU(3) structures we find Strominger-Hull systems, suitable for heterotic or type II string compactifications. These Strominger-Hull SU(3) structures needs to be supported by source terms in the associated Bianchi identity. We discuss the possibility of finding such source terms and present first steps towards their explicit construction. Provided suitable sources exist, our methods lead to Calabi-Yau compactifications of string theory with a non Ricci-flat, physical metric which can be written down explicitly and in analytic form. The talk is based on the paper 1805.08499.

Discussion Room: 4/3-006 - TH Conference Room

Pion scattering: from Lovelace-Shapiro to Neveu-Schwarz and beyond

• Massimo Bianchi (Dipartimento di Fisica & Sezione INFN - Università degli studi di Roma "Tor Vergata")

Room: 4/3-006 - TH Conference Room We show how to embed the Lovelace-Shapiro model for pion scattering in the Neveu-Schwarz fermionic string. In particular we relate the 4-point pion amplitude exposing Adler’s zero to a peculiar 4-point tachyon amplitude. We then show how to compute higher point amplitudes involving not only pions but also rho mesons and sigma particles and discuss the low-energy limit. We conclude with some caveats about the extension of the procedure to amplitudes with more than six insertions.

Discussion Room: 4/3-006 - TH Conference Room

De-conjecturing de Sitter

• Frederik Denef (Columbia University)

Room: 4/3-006 - TH Conference Room I will begin by reviewing some of the challenges one encounters when trying to make sense of quantum gravity in the presence of a positive vacuum energy density. In particular string theory in its present form appears inadequate to settle even basic existence questions. To resolve these issues, a more fundamental, possibly holographic, quantitatively precise framework will likely be needed. I will discuss some recent progress in this direction.

Discussion Room: 4/3-006 - TH Conference Room

Machine-Learning Algebraic & Geometric Structures: Implications to String Pheno

• Yang-Hui He (City University London)

Room: 4/3-006 - TH Conference Room We report some recent experiments in machine-learning applied to various mathematical problems such as computing Hodge numbers, recognizing elliptic fibrations, distinguishing finite simple groups, etc., many of which have direct consequences in string phenomenology. The mysterious success of the ML, often bypassing traditional expensive algorithms, potentially suggests hithertofore unseen structures.

Discussion Room: 4/3-006 - TH Conference Room

On de Sitter realisations in gravity and string theory

• Elias Kiritsis (APC et UoC)

Room: 4/3-006 - TH Conference Room We explore non-standard realizations of de Sitter solutions in string theory and associated theories of gravity based on ideas of the AdS/CFT correspondence.

Discussion Room: 4/3-006 - TH Conference Room

Flat Minkowski solutions from M-theory on G2 structure manifolds

• Giuseppe Dibitetto (Uppsala University)

Room: 4/3-006 - TH Conference Room I will consider dimensional reductions of M-theory on G2 structure manifolds with arbitrary constant torsion. I will construct a novel family of non-supersymmetric Minkowski extrema. These solutions are supported by pure geometry with no extra need for gauge fluxes and possess a tachyon free perturbative mass spectrum, up to a single flat direction. Such a direction corresponds to the overall internal volume, with respect to which the scalar potential exhibits a no-scale behavior. I will then conclude by discussing a possible mechanism to lift the flat direction to give it a positive squared mass while turning Mkw into dS. The construction makes use of the combined effect of flux and higher curvature corrections.

Discussion Room: 4/3-006 - TH Conference Room