Doctoral Course: 'AdS/CFT Holography as a Framework for Quantum Gravity’
2026-03-09 10:00 - 2026-03-12 12:00 (Europe/Madrid) | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Doctoral Course: ‘AdS/CFT Holography as a Framework for Quantum Gravity’

Lecturer: José Calderón-Infante
(Caltech)

Dates:
📅9, 10, 11, 12, 16, 17, 18 March 2026
🕒 10:00-12:00

Location:
📍Sala Azul, Instituto de Física Teórica (IFT)

Join Zoom Meeting
https://us02web.zoom.us/j/87999278090?pwd=[REDACTED]

Course Overview
This course provides an introduction toAdS/CFT holography, with a particular focus on its role as aframework for quantum gravity in asymptotically Anti-de Sitter (AdS) spacetimes.
We will begin by motivating the idea of holography in quantum gravity, reviewing the geometry and physics of AdS, and introducing some basics of conformal field theory (CFT). The course will then move to a more top-down perspective: after presenting the required ingredients of string theory, we will discuss Maldacena’s decoupling argument and the AdS/CFT correspondence it leads to, learning the AdS/CFT dictionary along the way.
The final part of the course will focus on AdS/CFT as a quantum gravity framework, covering topics such as:

Holographic CFTs

Black hole entropy in AdS/CFT

Basics of bulk reconstruction and its relation to the absence of global symmetries in quantum gravity

The Swampland Distance Conjecture in AdS/CFT

Prerequisites:
The course only requires basic knowledge of differential geometry and quantum field theory. While some elements of string theory will appear, all necessary ingredients will be introduced during the lectures.

Seminar: 'How string theory computes quantum gravity amplitudes'
2026-03-09 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘How string theory computes quantum gravity amplitudes’
Speaker: Lorenz Eberhardt (U. Amsterdam)
Venue&Time: Red Room / 15:00
Abstract: String theory provides a framework in which quantum gravitational scattering amplitudes are ultraviolet finite and computable in perturbation theory. These amplitudes are defined by integrating over the moduli space of Riemann surfaces, replacing the Feynman diagram expansion of field theory by a sum over worldsheet topologies. I will review how this definition arises and explain structural properties such as UV-finiteness, dual resonance and their Regge behavior. I will then discuss recent progress in explicit computations, focusing on one-loop amplitudes and new results on their high-energy behavior.

Cosmology Journal Club
2026-03-10 14:00 - 15:00, 2026-03-17 14:00 - 15:00
Every Tuesday at 2:00 PM in the discussion room on the 5th floor.
Join the IFT cosmology/gravity journal club at benty-fields.com to vote for papers and volunteer to present them.

SPS Journal Club: 'Quantum Obstructions to N=1 Infinite Distance Limits'
2026-03-12 12:00 - 13:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Strings, Pheno and the Swampland Journal Club
Title: ‘Quantum Obstructions to N=1 Infinite Distance Limits’
Speaker: Jeroen Monnee (U. Hamburg)
Venue&Time: Red Room / 12:00
Abstract: We study limits in the field space of 4d N=1 orientifold compactifications of Type IIB string theory with O3/O7-planes that descend from infinite distance limits in the complex structure moduli space of the underlying Calabi-Yau threefold. In particular, we investigate the fate of such limits in the quantum-corrected field space. We find that such orientifolds can be grouped into two classes, dubbed O-type A/B, whose behaviours vary dramatically at the quantum level. For O-type A limits, we observe that g_s-corrections become unsuppressed by observing that the degeneration of the geometry in the F-theory lift differs drastically from classical expectations. For O-type B limits we instead observe a similar behaviour for alpha’-corrections, based on the classical inconsistency of EFT string probes combined with explicit computations of such corrections. Based on upcoming work with Lukas Kaufmann, Timo Weigand, and Max Wiesner.

Pheno Journal Club
2026-03-12 12:00 - 15:00 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Every Tuesday at 15:00 in Grey Room 3.

Doctoral Course: ‘AdS/CFT Holography as a Framework for Quantum Gravity’ II
2026-03-16 10:00 - 2026-03-18 12:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Doctoral Course: ‘AdS/CFT Holography as a Framework for Quantum Gravity’ II

Lecturer: José Calderón-Infante
(Caltech)

Dates:
📅9, 10, 11, 12, 16, 17, 18 March 2026
🕒 10:00-12:00

Location:
📍Sala Azul, Instituto de Física Teórica (IFT)

Join Zoom Meeting
https://us02web.zoom.us/j/87999278090?pwd=[REDACTED]

Course Overview
This course provides an introduction toAdS/CFT holography, with a particular focus on its role as aframework for quantum gravity in asymptotically Anti-de Sitter (AdS) spacetimes.
We will begin by motivating the idea of holography in quantum gravity, reviewing the geometry and physics of AdS, and introducing some basics of conformal field theory (CFT). The course will then move to a more top-down perspective: after presenting the required ingredients of string theory, we will discuss Maldacena’s decoupling argument and the AdS/CFT correspondence it leads to, learning the AdS/CFT dictionary along the way.
The final part of the course will focus on AdS/CFT as a quantum gravity framework, covering topics such as:

Holographic CFTs

Black hole entropy in AdS/CFT

Basics of bulk reconstruction and its relation to the absence of global symmetries in quantum gravity

The Swampland Distance Conjecture in AdS/CFT

Prerequisites:
The course only requires basic knowledge of differential geometry and quantum field theory. While some elements of string theory will appear, all necessary ingredients will be introduced during the lectures.

Seminar: 'Effective Field Theory for Thermal Phase transitions'
2026-03-16 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title; ‘Effective Field Theory for Thermal Phase transitions’
Speaker: Mikael Chala (Granada)
Venue&Time: Red Room / 15:00
Abstract: I will present recent progress in applying effective field theory (EFT) to the precise computation of thermal phase transition parameters and the associated gravitational wave spectra. I will also briefly comment on byproducts of this work, including new methods for two-loop renormalization in EFT or skyrmion degrees of freedom emerging only at finite temperature.

DIFT Colloquium: 'The Mystery of Cosmic Acceleration'
2026-03-18 15:30 - 17:00 | IFT Auditorium, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, Madrid, 28049,, Spain
Title: The Mystery of Cosmic Acceleration

Speaker: Prof. David Weinberg, The Ohio State University, USA

Date and time: 15:30h (CET), Wednesday, March 18th, 2026

Location: CFTMAT Auditorium

After the talk, we will have a coffee gathering, providing an opportunity to continue the discussion and interact with the speaker in an informal setting.

Zoom link:
https://us02web.zoom.us/j/87376882248?pwd=[REDACTED]

Abstract:
Cosmic acceleration is one of the most surprising cosmological discoveries
of the past century. Even the “simplest” explanations require new,
cosmologically dominant energy components with exotic physical properties.
Current and near-future experiments are seeking clues to the origin of
cosmic acceleration by measuring the history of expansion and structure
growth with sub-percent precision over a wide span of redshift. I will
review the observational methods that underpin these measurements
and assess the current state of play, with particular attention to recent
measurements from the Dark Energy Spectroscopic Instrument (DESI) which
suggest that the properties of dark energy are evolving at a startling rate.
I will discuss the prospects and challenges for the new generation of
experiments — DESI, the Euclid mission, the Vera Rubin Observatory,
and the Nancy Grace Roman Space Telescope — which aim to sharpen cosmological
measurements by a factor of ten.

3rd EDI Training: Gender Perspective in Science
2026-03-19 11:00 - 13:30
3rd EDI Training – IFT Equity, Diversity and Inclusion Comitee Training Series
Speaker: Alejandra Gámez Abascal, researcher at the CBM. Chair of CBM Equality Committee. Member of Instituto Universitario de Estudios de la Mujer (IUEM).
Título: ‘Gender Perspective in Science and Research’
Venue&Time: Blue Room / 11:00
Coffee: 12:30 at the CFTMAT cafeteria.
Abstract:
In recent years, integrating a gender perspective into science and research has become a key priority within the European Research Area and international research policies. Beyond promoting equal opportunities, the gender dimension contributes to improving the quality, relevance, and impact of scientific knowledge.
This seminar will introduce key concepts and definitions related to gender equality in order to provide a conceptual framework for the main principles guiding gender-sensitive research.
We will explore the importance of incorporating gender perspectives at different stages of the research process, from research design and methodology to the analysis, interpretation, and dissemination of results. The seminar will also highlight current European policies and frameworks that promote gender equality in research institutions, including Gender Equality Plans and the integration of the gender dimension in research proposals, with the aim of supporting researchers in integrating gender perspectives into their scientific work.

This seminar aligns with the objectives of the scientific outreach and culture component outlined in the Severo Ochoa project (CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033). In addition to scientific excellence, this project highlights the center’s commitment to a strong program of training and outreach activities with high social impact. In this context, organizing training activities on equality, diversity, and inclusion helps to reinforce the role of the IFT as an institution committed to social responsibility and the continuous improvement of the scientific environment. This seminar provides tools to analyze the structural barriers present in the scientific field, particularly in STEM disciplines such as theoretical physics, aligning with the objectives of attracting and retaining diverse talent that foster an inclusive scientific environment.

SPS Journal Club: 'Axion-Scalar Systems and Dynamical Distances'
2026-03-19 12:00 - 13:00
Strings, Pheno and the Swampland (SPS) Journal Club
Speaker: Gonzalo F. Casas (IFT)
Title: ‘Axion-Scalar Systems and Dynamical Distances’
Abstract: We study the cosmology of axion-scalar pairs, coupled by a hyperbolic field-space metric and with a string-motivated rational scalar potential. Borrowing tools from the theory of dynamical systems, we are able to classify all late-time trajectories and extract physical properties of the asymptotic solutions. These results suggest a Dynamical Distance Conjecture: along the physical (possibly non-geodesic) trajectories, towers of states become exponentially light as a function of the traversed field-space distance. We further rule out possible counterexamples with wildly oscillating solutions. The considered axion-scalar systems are realized in F-theory compactifications, where the axion-scalar pair is a complex-structure modulus and four-form fluxes induce the asymptotic potentials. We also provide a complete Hodge-theoretic classification of all one-modulus asymptotic potentials of this type.

Seminar: 'Beyond the Minimal Axion: Robustness of Standard Predictions'
2026-03-19 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘Beyond the Minimal Axion: Robustness of Standard Predictions’
Speaker: Sung Mook Lee (CERN)
Venue & Time: Red Room / 15:00
Abstract: The QCD axion is one of the most compelling candidates for physics beyond the Standard Model, as it can simultaneously solve the strong CP problem and account for the dark matter abundance. In the minimal single-axion framework, especially in a post-inflationary cosmology, the combination of axion gauge coupling quantization and axion production from string networks leads to sharp and highly predictive targets. In this talk, we revisit these predictions in a simple but realistic setup with an additional confining dark gauge group and extra axion degrees of freedom. We will show how axion mixing and defect dynamics can modify both the coupling predictions and the relic abundance expectations through emergent features specific to multi axion scenarios, and discuss when the standard single axion benchmarks remain reliable. This provides a useful test of what remains truly robust in extended axion theories and helps guide current experimental targets.

4º ESO + Empresa Programme at IFT
2026-03-23 09:30 - 2026-03-26 14:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
As part of the 4º ESO + Empresa educational programme, the Instituto de Física Teórica (IFT) will host a group of secondary-school students from 23 to 26 March.
During their stay, students will participate in a series of outreach and educational activities designed to provide a general introduction to theoretical physics research and the day-to-day work carried out at the institute. The programme will include interactive talks, workshops, and guided discussions on selected topics in contemporary physics.
The aim of this initiative is to familiarise students with the research environment of a theoretical physics institute and to offer them a broad perspective on current scientific questions and research practices.
Tutors / CoordinatorsÁngel Uranga UrteagaAlberto Casas GonzálezCarlos Pena RuanoLaura Marcos MateosCarolina Saggiomo Blanco
More info: https://workshops.ift.uam-csic.es/esoempresa

Seminar: 'Observing Quantum Gravity in Extremely Cold Horizons'
2026-03-23 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘Observing Quantum Gravity in Extremely Cold Horizons’
Speaker: Roberto Emparan (Universidad de Barcelona)
Venue&Time: Red Room / 15:00
Abstract: Recent developments have revealed that black holes near extremality exhibit large quantum fluctuations in their geometry, marking a controllable breakdown of semiclassical quantum field theory in curved spacetime. In this talk, I will discuss how these fluctuations can be revealed through scattering waves off the black hole. In particular, we find that extremely cold black holes become transparent to low-frequency light or gravitational radiation. Although such signatures are extraordinarily hard to detect, they provide concrete signatures of quantum gravity at play in near-extremal regimes.

Cosmology Journal Club
2026-03-24 14:00 - 15:00, 2026-04-07 14:00 - 15:00, 2026-04-14 14:00 - 15:00 | Discussion room 5th floor, C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, Madrid, 28049, Spain
Every Tuesday at 2:00 PM in the discussion room on the 5th floor.
Join the IFT cosmology/gravity journal club at benty-fields.com to vote for papers and volunteer to present them

PhD Defense by Marienza Caldarola: 'Unveiling the Universe with Gravitational Waves: a Machine Learning approach'
2026-03-25 10:30 - 13:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: Unveiling the Universe with Gravitational Waves: a Machine Learning approach

Venue & Time: Blue Room / 10:30

Abstract: This thesis is devoted to the study of gravitational waves, combining theoretical investigations with novel applications of machine learning. The first part of the work addresses the dynamics of hyperbolic encounters, a class of transient gravitational wave signals. By incorporating orbit precession and post-Newtonian corrections, this study provides theoretical insights into the emission properties.
The second part shifts toward data-driven approaches, exploring the use of advanced machine learning methods in gravitational waves field. Two main applications are considered: constraining the energy density of the stochastic gravitational wave background through astrometric measurements and inferring the properties of lensed gravitational wave signals. In both cases, the machine learning frameworks developed here show significant gains in computational efficiency, with particular promise for real-time signal analysis and alerts, demonstrating the transformative role of machine learning in enhancing current and future gravitational wave data analysis strategies.

Supervisors: Savvas Nesseris and Sachiko Kuroyanagi

IFT Colloquium: 'QCD critical point and the predictable randomness of relativistic fluids'
2026-03-25 12:00 - 13:30 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘QCD critical point and the predictable randomness of relativistic fluids’
Speaker: Misha A. Stephanov (Illinois U., Chicago)
Venue&Time: 12:00 / Red Room
Abstract: Quantum Chromodynamics predicts a variety of unusual states of matter in which relativity and quantum many-body physics strongly intertwine. Discovering phase transitions between these extreme forms of matter in a laboratory is an unprecedented task. This is the challenge heavy-ion collision experiments are taking up at the Relativistic Heavy-Ion Collider (RHIC) and future facilities. An intriguing open question is the existence and the location of the QCD critical point. Similar critical points are ubiquitous in earthly substances and the associated fluctuation driven phenomena are remarkably universal. Can the QCD critical point be discovered in the heavy-ion collision experiments? It is a nontrivial question in large part because of the importance of the explosive dynamics of the collision. This challenging question is a subject of current research and a major motivation for recent developments in relativistic hydrodynamics. Of particular interest in this context is the dynamics of thermal fluctuations inherent in any system with dissipation.

Quantum Information Journal Club: 'Rapid mixing for Gibbs measures in Riemannian manifolds'
2026-03-25 14:30 - 15:30 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Speaker: Pablo Páez-Velasco (Universidad Complutense de Madrid)
Venue & Time: Gray Room 2 / 14:30
Abstract: Given some sufficiently smooth, generally non-convex, function F on a Riemannian manifold, and a fixed inverse temperature, the problem of sampling with respect to the associated Gibbs distribution has played a central role in several areas, such as statistical mechanics or non-convex optimization. A natural approach to do so is to simulate the Langevin diffusion associated to F, whose stationary distribution is precisely the Gibbs distribution. However, obtaining quantitative convergence guarantees in this non-convex, geometric setting remains difficult.
In this work, we identify a set of assumptions on F and the underlying manifold under which a log-Sobolev inequality (LSI) holds for the Gibbs distribution in the low-temperature regime. As a consequence, we obtain exponential convergence of the Langevin diffusion to its stationary distribution.

Pheno Journal Club: 'Powerful Yukawas'
2026-03-26 12:00 - 13:00 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Every Thursday at 12:00 in Grey Room 2.
Marta Fuentes (IFT), will present “Powerful Yukawas”.

We introduce a class of models where the masses of the light Standard Model fermions are due to an Effective Field Theory operator that appears beyond dimension-4 in the power counting expansion, resulting in a `Powerful Yukawa’. The effective Yukawa coupling structure is UV-completed using a collective symmetry breaking pattern in the flavour sector, which we dub `Sprouted Symmetry Breaking.’ The irreducible signature is an enhanced Higgs coupling to the light Standard Model fermions.

SPS Journal Club: 'M-theory on S^1 vee S^1 as Type 0A'
2026-03-26 12:00 - 13:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Strings, Pheno & The Swampland Journal Club | Every Thursday at 12:00 in the Red Room.
Speaker: Salvatore Raucci (IFT)
Title: ‘M-theory on S^1 vee S^1 as Type 0A’
Abstract: We propose an exotic geometric M-theory dual for the weak coupling Type 0A string: compactification on a sub-Planckian S^1 vee S^1 (two circles connected at a point), where strong quantum effects lead to fields living on distinct resolutions of that space. Moreover we argue that tachyon condensation of the 0A theory corresponds to shrinking of one of the two circles leading to the IIA supersymmetric string. We use this and other dualities to provide an F-theoretic description of the axio-dilaton and the tachyonic field of Type 0B and argue for the existence of a strong coupling critical point of the potential using the resulting duality symmetry Γ_0(2) ⊂ SL(2,Z). The existence of this critical point can also be argued using conventional M-theory dualities. If this critical point is unique it is an unstable dS vacuum. Using this we propose a strong coupling conformal fixed point for a non-supersymmetric gauge theory in four dimensions living on coincident D3^+ — D3^- branes of 0B.

HoloClub: 'Semi-classical aspects of black holes: recent progress and future directions'
2026-04-07 11:30 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘Semi-classical aspects of black holes: recent progress and future directions’
Speaker: Juan F. Pedraza (IFT)
Venue & Time: Gray Room 3 / 11:30
Abstract: Semi-classical gravity provides a valuable framework for exploring quantum effects in black hole physics, particularly in regimes where a complete theory of quantum gravity remains out of reach. In this talk, I will review recent progress in the description of black holes in braneworld gravity, where holographic constructions allow semi-classical backreaction to be incorporated in a controlled manner. I will discuss how these setups give rise to quantum-corrected black hole solutions and why they provide a promising arena for black hole phenomenology. In the final part of the talk, I will outline a few possible calculations and open directions, emphasizing concrete questions that may be worth pursuing in future work.

Pheno Journal Club
2026-04-09 12:00 - 13:00 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Every Thursday at 12:00 in Grey Room 3.

Strings, Pheno and the Swampland (SPS) Journal Club
2026-04-09 12:00 - 17:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Every Thursday at 12:00 in the Red Room.

Seminar: 'EFTs for BSM: Counting, Ambiguities, and Application'
2026-04-09 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘EFTs for BSM: Counting, Ambiguities, and Application’

Speaker: Shakeel Ur Rahaman (IPPP Durham).

Venue&Time: Red Room / 15:00
Abstract: The two principal frameworks for modeling the Beyond Standard Model physics as an Effective Field Theory (EFT) are the Standard Model EFT (SMEFT) and the Higgs Effective Field Theory (HEFT). SMEFT is constructed in the electroweak symmetric phase, inherently utilizing the Higgs doublet, whereas HEFT is defined in the broken phase using the physical Higgs boson alongside a separate set of Goldstone bosons. The unavoidable necessity of truncating these effective field theory expansions creates technical ambiguities that are fundamentally interwoven with the redundancies inherent in general field redefinitions. In this talk regarding HEFT, the focus will be primarily on its methodology for building operators, its power counting scheme, and the associated truncation uncertainties. These properties are already well-established within the SMEFT framework. For SMEFT, the discussion will center on its application in precision calculations and its practical implementation in Monte Carlo event generators such as Sherpa.

POSTPONED: HoloClub: 'Holographic transport in anisotropic systems'
2026-04-14 11:30 - 13:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: Holographic transport in anisotropic systems
Speaker: Claire Moran (Utrecht University)
Venue&Time: Red Room / 11:30
Abstract: Understanding transport in strongly coupled quantum systems remains a central challenge across high-energy physics, condensed matter, and quantum many-body theory. Of particular interest is systems exhibiting anisotropy, where the anisotropy leads to a much richer transport structure, with new transport coefficients emerging. The bulk viscosity becomes especially subtle in anisotropic media, where it can couple nontrivially to directional degrees of freedom and underlying microscopic structure. In this talk, I will discuss a recently developed holographic method for computing the bulk viscosity in such systems. This approach circumvents technical obstacles present in existing treatments and yields analytic expressions. I will discuss the general structure of the method, and highlight some applications of it.

Quantum Information Journal Club: 'Accessible quantum correlations under complexity constraints'
2026-04-15 14:30 - 15:30 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘Accessible quantum correlations under complexity constraints’
Speaker: Álvaro Yangüez (Sorbonne Université Paris)
Venue&Time: Gray Room 3 / 14:00
Abstract:

Quantum systems may contain underlying correlations which are inaccessible to computationally bounded observers. We capture this distinction through a framework that analyses bipartite states only using efficiently implementable quantum channels. This leads to a complexity-constrained max-divergence and a corresponding computational min-entropy. The latter quantity recovers the standard operational meaning of the conditional min-entropy: in the fully quantum case, it quantifies the largest overlap with a maximally entangled state attainable via efficient operations on the conditional subsystem. For classical-quantum states, it further reduces to the optimal guessing probability of a computationally bounded observer with access to side information. Lastly, in the absence of side information, the computational min-entropy simplifies to a computational notion of the operator norm. We then establish strong separations between the information-theoretic and complexity-constrained notions of min-entropy. For pure states, there exist highly entangled families of states with extremal min-entropy whose efficiently accessible entanglement in terms of computational min-entropy is exponentially suppressed. For mixed states, the separation is even sharper: the information-theoretic conditional min-entropy can be highly negative while the complexity-constrained quantity remains nearly maximal.

Overall, our results demonstrate that computational constraints can fundamentally limit the quantum correlations that are observable in practice.

Pheno Journal Club: Unitarity limits on triple gauge boson production
2026-04-16 12:00 - 13:00 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Daniel Domenech Moya (IFT) will present “Unitarity limits on triple gauge boson production”.

Venue & Time: Gray Room 2 / 12:00

Abstract:

We derive the unitarity constraints on anomalous quartic gauge couplings originating from the f ¯f ′ → V V ′V ′′ channel with V (′)(′′) = γ, Z, W ±, and H. We also assess the importance of these bounds on the present and future experimental searches.

Strings, Pheno and the Swampland (SPS) Journal Club
2026-04-16 12:00 - 13:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Every Thursday at 12:00 in the Red Room.
Titulo: The Art of Branching: Cobordism Junctions of 10d String Theories
Speaker: Edoardo Anastasi (IFT)
Abstract: We describe the explicit construction of configurations of several 10d string theories joining at a 9d junction, providing a dynamical realization of cobordisms between multiple 10d string theories, predicted by the Cobordism Conjecture. We provide the microscopic worldsheet description of the configuration in a generalization of the `going up and down the RG flow’ interpolations recently used in the description of IIA/IIB domain wall. The interpolations involve additional degrees of freedom, which are gapped except at the branch point, at which the gap closes and triggers the branching transition. The extra degrees of freedom admit an interpretation in terms of additional dimensions in a supercritical string theory, which reduces to the 10d junction configuration upon closed tachyon condensation. Quantum corrections of the 2d worldsheet theory turn the junction into a strongly coupled lightlike core whose UV resolution lies beyond worldsheet techniques. We construct explicit examples of junctions of 10d heterotic string theories, type 0, and type II theories and orientifolds thereof. Our explicit examples include junctions of 10d chiral theories whose chiral fields flow between different branches. One particularly nice configuration is a 4-branch junction of the IIB theory, with type I, the non-supersymmetric USp(32) theory and the U(32) orientifold of 0B theory, thus assembling the four non-tachyonic descendants of type 0B theory.
