XIX AVOGADRO MEETING on Strings, Supergravity and Gauge Theories

20 Dec 2023, 08:30 → 22 Dec 2023, 19:00 Europe/Rome

Padova, Scuola della Carità

Lorenzo Bianchi (Istituto Nazionale di Fisica Nucleare), Federico Carta, Stefano Massai (Istituto Nazionale di Fisica Nucleare), Francesco Muia (University of Cambridge), Natalia Pinzani Fokeeva (University of Florence), Charlotte Sleight (Istituto Nazionale di Fisica Nucleare)

 

The Avogadro Meetings started in 2005 as an occasion for young Italian theoretical physicists to share their ideas and results in an informal atmosphere. The meeting is named after the University of Piemonte Orientale that hosted its first three editions.

The meeting is traditionally scheduled just before the Christmas break to facilitate the participation of Italian postdocs and PhD students working abroad who can take the chance of their travel back home for Christmas to meet young colleagues and exchange ideas.

In order to stress the pedagogical aim of the meeting, preference is given to extended presentations on general themes rather than to conventional seminars on specific works, possibly organised and illustrated by more than one speaker and followed by a long discussion session.

Consistently with the original spirit of the event, the invited speakers are usually Italian. However participation is open to anybody and non-Italians are more than welcome to join. For this reason the seminars are presented in English.

The XIX edition will take place in Padova.

Organizing committee

• Lorenzo Bianchi
• Federico Carta
• Stefano Massai (local organizer)
• Francesco Muia
• Natalia Pinzani Fokeeva
• Charlotte Sleight

Secretariat

• Marina Andreazzo
• Pina Salente
• Silvana Schiavo
• Paola Zenere

Poster_Avogadro.pdf

Wednesday, 20 December

The Cosmological Bootstrap

1 The Cosmological Bootstrap - Part 1

Speaker: Giovanni Cabass (Ruđer Bošković Institute)

10:30 Coffee break

The Cosmological Bootstrap

2 The Cosmological Bootstrap - Part 2

Speaker: Carlos Duaso Pueyo (University of Cambridge)

3 The Cosmological Bootstrap - Discussion session

13:00 Lunch break

Gong Show

4 Freund-Rubin compactifications of non-supersymmetric strings

I will discuss Freund-Rubin compactifications of tachyon-free superstring theories that have no spacetime supersymmetry in their ten-dimensional formulation. A common feature of these models is the presence of scalar potentials in the low-energy physics, known as tadpole potentials, which correspond to vacuum energies in quantum field theories.
These tadpole potentials can play crucial roles in flux compactifications, and one can engineer Freund-Rubin vacua by balancing tree-level fluxes with one-loop vacuum energies. I will comment on the stability of these solutions and their connections with charged branes.

Speaker: Salvatore Raucci (Istituto Nazionale di Fisica Nucleare)

5 Free energy on the sphere for non-abelian gauge theories

We compute the Sd partition function of the fixed point of non-abelian gauge theories in continuous d, using the ϵ-expansion around d = 4. We obtain the result up to NLO, i.e. including two-loop vacuum diagrams. Depending on the sign of the one-loop beta function, there is a fixed point with real gauge coupling in d > 4 or d < 4. In the first case, we extrapolate to d = 5 to test a recently proposed construction of the UV fixed point of 5d SU(2) Yang-Mills via a susy-breaking deformation of the E1 SCFT. In the second case, we extrapolate to d = 3 to test whether QCD3 with gauge group SU(nc) and nf fundamental matter fields flows to a CFT or to a symmetry-breaking case.

Speaker: Fabiana De Cesare (Istituto Nazionale di Fisica Nucleare)

6 Geometry of Cosmological Correlators

We study correlators of a class of scalar toy models in cosmological background. These can be computed from the so-called wavefunction of the universe which in turn is given by the canonical form of the cosmological polytope. We find that a simple geometrical operation on the cosmological polytope gives a geometry whose canonical form gives the correlator. We initiate the study of its boundary structure and triangulations identifying new set of soft limits and positivity bounds.

Speaker: Gabriele Dian (DESY Hamburg)

7 Spinning partial waves for scattering amplitudes in any dimension

Partial wave decomposition is one of the main tool within the S-matrix bootstrap. However, a comprehensive understanding of partial waves beyond four dimensions is currently lacking. We present a method to compute all partial waves for 2-to-2 scattering of spinning particles in arbitrary dimension.

Speaker: Francesco Russo (University of Pisa)

8 Remodeling Equivariant GLSMs

Topological Recursion (TR) is the mathematical framework that governs the genus expansion of matrix integrals. In physics, TR has a wide range of applications: it computes correlation functions in matrix models, amplitudes in topological string theory, partition functions of JT (super)gravity and more. In this talk I will introduce the theory of Eynard-Orantin TR and outline the novel application to equivariant Gauged Linear Sigma Models and the physics of A-branes. Based on upcoming work.

Speaker: Davide Scazzuso (HU Berlin)

9 The gravitational nature of generalized TTbar deformations

TTbar deformations provide remarkable insights into the topology and geometry of the space of field theories, as well as allowing exact calculations of physical quantities related to lower-dimensional deformed field theories. Noteworthy connections with theories of gravity have been shown to hold in two-dimensional spacetime. We discuss the extension of such correspondences to higher dimensional spacetimes, through the introduction of non-trivial, higher-derivative theories of gravity.

Speaker: Tommaso Morone (Università di Torino)

10 AdS2 vacua from SL(2,R) T-Duality

The AdS$_2$/CFT$_1$ correspondence plays a key role in the microscopical description of extremal black holes, AdS$_2$ being part of the geometry that appears in their near horizon limit in any dimension. 
Another useful application of the AdS$_2$/CFT$_1$ correspondence is to the holographic description of superconformal line defects in higher dimensional CFTs. Geometrically, a sign that an AdS$_2$ solution may be describing a superconformal line defect is that it flows asymptotically locally to a higher dimensional AdS background, dual far from the defects to the higher dimensional CFT in which they are embedded.
I will present general results on the construction of AdS$_2$ solutions to Type II supergravity via U(1) and SL(2) T-dualities, paying special attention to the conditions for preservation of supersymmetry. I then exploit these to construct new classes of small ${\cal{N}} = 4$ solutions in Type II supergravity.
I also applied this procedure to two solutions in Type IIA Supergravity with $\mathbb{CP}^3$ along the internal space. These preserve ${\cal{N}}=(5,0)$ or ${\cal{N}}=(6,0)$ supersymmetry and realise the superconformal algebras $osp(5|2)$ and $osp(6|2)$. This results in four new classes of AdS$_2$ solutions, realising these superconformal algebras, hinting that a more general class AdS$_2 \times \mathbb{CP}^3 \times \Sigma$ may exist.

Speaker: Mr Andrea Conti (University of Oviedo)

11 Analytical bootstrap for the O(3) magnetic impurity

Extended operators such as defects are of fundamental importance in conformal field theories, with applications both to high energy theory and to condensed matter systems at criticality. Recently, analytic bootstrap techniques have been successfully applied to investigate these objects.

In this talk, we will focus on the O(3) magnetic impurity, which at the fixed point is described by a defect conformal field theory. Firstly, we will use symmetries and renormalization group techniques to study the light defect spectrum of this model the 4-ε expansion, which turns out to be quite rich. Once the defect spectrum is known, analytic bootstrap techniques are applied to bulk two-point functions to extract an infinite amount of new dCFT data.

Speaker: Elia De Sabbata (Istituto Nazionale di Fisica Nucleare)

12 Non-unitary multicriticality in two dimensions

I will present recent developments in the understanding of non-unitary multicriticality in two-dimensions based on JHEP 02 (2023) 046, JHEP 09 (2023) 052 and work in progress.
We study the non-unitary, PT symmetric deformations of the two-dimensional Tricritical Ising Model obtained by coupling its two spin Z2 odd operators to imaginary magnetic fields. We establish the presence of two universality classes of infrared fixed points on the critical surface, separating PT symmetric and PT spontaneously broken phases. The first class corresponds to the familiar Yang-Lee edge singularity, while the second class to its tricritical version. We argue that these two universality classes are controlled by the conformal non-unitary minimal models (2, 5) and (2, 7) respectively, which is supported by considerations based on PT symmetry and the corresponding extension of Zamolodchikov’s c-theorem, and also verified numerically using the truncated conformal space approach. Our results are in agreement with a previous numerical study of the lattice version of the Tricritical Ising Model. We also conjecture the classes of universality corresponding to higher non-unitary multicritical points obtained by perturbing the conformal unitary models with imaginary coupling magnetic fields. If correct, it implies the existence of a tower of RG flows among the minimal models (2,2n+3) analogous to the Zamolodchikov's flows among unitary minimal models. Even if they cannot be discussed by using (conformal) perturbation theory and are not integrable flows, we tested the existence of the flows among the minimal models (2,2n+3) numerically, by using truncated conformal space approach in JHEP 09 (2023) 052. We established the existence of the aforementioned flows for critical, tricritical and tetracritical version of the Lee-Yang, making stronger the conjecture on the non-unitary multicritical theory. In the last paper we also observed for the first time some non-critical breaking of PT symmetry. We argue that this exists because of an absence of an order parameter for such a symmetry breaking.

Speaker: Alessio Miscioscia (Desy (Hamburg))

13 Broken (super) conformal Ward identities at finite temperature

I will present recent developments in the understanding of conformal field theories at finite temperature, based on hep-th/2306.12417.
When a (super) conformal field theory is placed on a non-trivial manifold, the (super) conformal symmetry is broken. However, it is still possible to derive broken Ward identities for these broken symmetries, which provide additional constraints on the theory. I will discuss how to derive and apply the broken Ward identities associated with the (super) conformal group on the thermal manifold $\mathcal{M}_{\beta}=S^{1}_{\beta} \times \mathbb{R}^{d-1}$, and I will show how the novel constraints not only systematically reproduce known results, including an implicit formulation of the generalized Cardy formula, but also elegantly relate the thermal energy spectrum with the conformal spectrum.

Speaker: Enrico Marchetto

14 TBD

Speaker: Davide Bason (University of Torino)

15 Gravitational Axiverse Spectroscopy: Seeing the Forest for the Axions

We consider inflationary models with multiple spectator axions that couple to dark Abelian gauge sectors. We demonstrate a distinctive phenomenon that make this class of models attractive -- we show that separation of the gravitational wave peaks can occur, depending on the axion initial conditions and mass. This leads to a distinctive gravitational wave (GW) forest, whose observation would be a signal that multiple axions exist within the universe. Finally, we elaborate on possible ultraviolet origins of the spectator models utilizing string axions descending from p-form gauge field coupled to D-branes. String theory compactifications generically produce an `axiverse', that is, many of these string axions. Their coupling to D-branes in turn generates CS couplings to dark gauge fields which can be enhanced via multiple brane wrappings and/or fluxes. If these string axions then undergo slow-roll during inflation, they produce GW signals with peaked frequency distribution which are potentially detectable. We discuss the non-trivial requirements for such U(1) gauge field coupled string axions to occur in type IIB string compactifications on Calabi-Yau orientifolds with fluxes, and provide a rudimentary classification of some options.

Speaker: Margherita Putti (Hamburg University UHH - DESY)

16 Higher-point lightcone bootstrap in the comb channel

It is a well-established fact that any conformal field theory with a gap in the twist spectrum must contain families of multi-twist operators, whose spectrum at large spin approaches that of generalized free theory. In this talk, we aim to discuss how the lightcone bootstrap can be applied to five- and six-point correlation functions in the comb channel to constrain the behavior of double- and triple-twist operators. Our analysis yields new expressions for large-spin OPE coefficients involving two double-twist operators, as well as the leading-order anomalous dimension matrix for triple-twist operators. The latter offers valuable insight into how the degeneracy of triple-twist primaries in the free-theory limit gets lifted by the inclusion of interactions.

Speaker: Lorenzo Quintavalle (Laval University)

17 Remarks on BPS Wilson loops in non-conformal N=2 gauge theories and localization

We consider 1/2 BPS supersymmetric circular Wilson loops in four-dimensional N = 2 SU( N ) SYM theories with massless matter in a generic representation of the gauge group and a non-vanishing β-function (arxiv:2311.17692). Following Pestun's approach, we can employ localization to map these observables, evaluated on the four-sphere S^4, into a matrix model, provided that the one-loop determinants are consistently regularized. After constructing the regularized matrix model for these set-ups, I will demonstrate that the predictions for the Wilson loop at order g^4 perfectly match the perturbative renormalization based on the evaluation of Feynman diagrams both on the sphere and, remarkably, in flat space, even if conformal symmetry is broken at the quantum level. Moreover, I will revisit the difference theory approach, showing that when β-function is non-vanishing this method does not account for the presence of “evanescent” terms which are activated by the renormalization procedure and contribute to the renormalized observable at order g^6.

Speaker: Alessandro Testa (Istituto Nazionale di Fisica Nucleare)

18 Is action complexity better for dS space in JT gravity?

Holographic complexity is supposed to capture the evolution of spacetime. In two-dimensional de Sitter (dS), volume complexity remains O(1) up to a critical time, after which it suddenly diverges. On the other hand, in (d>2)-dimensional dS, complexity becomes very large even before the critical time. In Jackiw-Teitelboim (JT) gravity, taking into account the dilaton, the same behavior is expected for complexity in two-dimensional dS. We show that this expectation is met by action complexity, which we explicitly compute by performing half reduction from three-dimensional dS. In addition, we propose an appropriate Weyl field-redefinition such that volume avoids the discontinuous jump in time evolution. Since action complexity directly takes into account the dilaton and does not suffer the Weyl-field redefinition ambiguity which affects volume complexity, we argue that action is better than volume for dS in JT gravity.

Speaker: Nicolò Zenoni (Department of Physics, Osaka University)

Poster session

18:00 Welcome Cocktail

Thursday, 21 December

Axions from String Theory

19 Axions from String Theory - Part 1

Speaker: Filippo Revello (Utrecht University)

10:30 Coffee break

Axions from String Theory

20 Axions from String Theory - Part 2

Speaker: Nicole Righi (King's College London)

21 Axions from String Theory - Discussion session

13:00 Lunch break

Generalized Global Symmetries in Quantum Field Theory

22 Generalized Global Symmetries in Quantum Field Theory - Part 1

Speaker: Mr Alessandro Mininno (Instituto de Fisica Teorica UAM-CSIC)

16:00 Coffee break

Generalized Global Symmetries in Quantum Field Theory

23 Generalized Global Symmetries in Quantum Field Theory - Part 2

Speaker: Christian Copetti (Oxford)

24 Generalized Global Symmetries in Quantum Field Theory - Discussion session

Friday, 22 December

Non-perturbative Techniques for Superconformal Theories

25 Non-perturbative Techniques for Superconformal Theories - Part 1

Speaker: Francesco Galvagno (ETH Zuerich)

10:30 Coffee break

Non-perturbative Techniques for Superconformal Theories

26 Non-perturbative Techniques for Superconformal Theories - Part 2

Speaker: Giulia Fardelli (Boston University)

27 Non-perturbative Techniques for Superconformal Theories - Discussion session

13:00 Lunch break

Von Neumann Algebras and Quantum Gravity

28 Von Neumann Algebras and Quantum Gravity - Part 1

Speaker: Eyoab Dejene Bahiru (SISSA)

16:00 Coffee break

Von Neumann Algebras and Quantum Gravity

29 Von Neumann Algebras and Quantum Gravity - Part 2

Speaker: Niloofar Vardian (SISSA)

30 Von Neumann Algebras and Quantum Gravity - Discussion session