String Geometry and String Phenomenology Institute

17 Jun 2019, 08:00 → 28 Jun 2019, 18:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

This two-week programme investigates the fruitful interplay between string theory, high energy particle physics, quantum gravity and geometry in the context of string compactifications.

The first week (17-21 June) is in the format of a smaller workshop, with ample space for discussions and interactions.

The second week of the programme (24-28 June) is devoted to the annual String Phenomenology Conference.

 

Topics include:

• Swampland and Quantum Gravity Conjectures 
• Formal and Mathematical Aspects of string compactifications (such as F-theory, G2 compactifications, heterotic compactifications, and other corners of the string landscape, e.g. non-geometric compactifications)
• String Model Building in particle physics and cosmology
• Machine Learning Techniques to explore the String Landscape

 

Key Speakers include:

Bobby Acharya Massimo Bianchi Andreas Braun Andres Collinucci Joe Conlon Michele DelZotto Frederik Denef Giuseppe Dibitetto

Anamaria Font Antonella Grassi Elias Kiritsis Magdalena Larfors Stefano Massai Roberto Valandro Patrick Vaudrevange Dan Waldram

 

As organisers of this conference, we feel responsibility for its environmental impact, and will do our best to minimize it. We believe that as a community, we should take our share on this matter. We refer you to a list of suggestions, the "Green Tips", to help us in this goal.

Local Organizers:

David Andriot, Alessandra Gnecchi, Seung-Joo Lee, Wolfgang Lerche, Fabian Ruehle, Konstantinos Siampos, Timo Weigand

 

Restaurant2.pdf

Schedule_institute.pdf

Monday, 17 June

09:30 → 10:00 Coffee break

10:00 → 10:45 M-theory singularities: Going beyond Dynkin diagrams

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.

Speaker: Andres Collinucci (Université Libre de Bruxelles)

Collinucci.pdf

Recording

10:45 → 11:00 Discussion

11:00 → 11:45 Singularities and F-theory

I will review background results and discuss recent progress.

Speaker: Antonella Grassi (University of Pennsylvania)

Grassi.pdf

Recording

11:45 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 5d SCFTs and their gauge theory phases

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.

Speaker: Michele del Zotto (Durham University)

Recording

14:45 → 15:00 Discussion

16:30 → 17:00 TH Coffee break

19:30 → 21:30 Dinner

Tuesday, 18 June

09:30 → 10:00 Coffee Break

10:00 → 10:45 G2 and String Dualities

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.

Speaker: Andreas Braun (University of Oxford)

Recording

10:45 → 11:00 Discussion

11:00 → 11:45 New G2 conifolds in M theory and their Gauge Theory Interpretations

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.

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

Recording

11:45 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 15:00 The Swampland, Moduli and Holography

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.

Speaker: Joe Conlon (University of Oxford)

Recording

15:00 → 15:45 Coffee Break

15:45 → 16:30 High charges in M-theory and F-theory

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.

Speaker: Roberto Valandro (ICTP Trieste & INFN)

Recording

16:30 → 16:45 Discussion

Wednesday, 19 June

09:30 → 10:00 Coffee Break

10:00 → 10:45 Moduli for generic N=1 flux backgrounds

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.

Speaker: Dan Waldram (Imperial College)

Recording

10:45 → 11:00 Discussion

11:00 → 11:45 Comments on F-theory/heterotic duality in 8 dimensions

Speaker: Anamaria Font (Universidad Central de Venezuela)

cs4.pdf

Recording

11:45 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 Phases of little string theory and fuzzballs

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.

Speaker: Stefano Massai (University of Chicago)

Massai_CERN.pdf

Recording

14:45 → 15:00 Discussion

16:30 → 17:00 Coffee Break

Thursday, 20 June

09:30 → 10:00 Coffee Break

10:00 → 10:45 Unification of Symmetries from Strings

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.

Speaker: Patrick Vaudrevange (TU Munich)

Patrick Vaudrevange talk

Recording

10:45 → 11:00 Discussion

11:00 → 11:45 SU(3) structures on Calabi-Yau manifolds

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.

Speaker: Magdalena Larfors (Uppsala University)

Larfors_stringpheno19.pdf

Recording

11:45 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 Pion scattering: from Lovelace-Shapiro to Neveu-Schwarz and beyond

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.

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

Recording

14:45 → 15:00 Discussion

15:00 → 15:45 De-conjecturing de Sitter

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.

Speaker: Frederik Denef (Columbia University)

Recording

15:45 → 16:00 Discussion

16:00 → 16:30 Coffee Break

Friday, 21 June

09:30 → 10:00 Coffee Break

10:00 → 10:45 Machine-Learning Algebraic & Geometric Structures: Implications to String Pheno

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.

Speaker: Yang-Hui He (City University London)

Recording

10:45 → 11:00 Discussion

11:00 → 11:45 On de Sitter realisations in gravity and string theory

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.

Speaker: Elias Kiritsis (APC et UoC)

Kiritsis-CERN.pdf

Recording

11:45 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 Flat Minkowski solutions from M-theory on G2 structure manifolds

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.

Speaker: Giuseppe Dibitetto (Uppsala University)

Dibitetto-CERN.pdf

Recording

14:45 → 15:00 Discussion

16:30 → 17:00 Coffee Break