Instituto de Física Teórica

Cosmology Journal Club
2025-10-14 14:00 - 15:00, 2025-10-21 14:00 - 15:00, 2025-10-28 14:00 - 15:00, 2025-11-04 14:00 - 15:00, 2025-11-18 14:00 - 15:00 (Europe/Madrid) | 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.

Machine Learning and AI Journal Club
2025-10-16 11:00 - 12:00 | Gray Room 1, Instituto de Física Teórica, C/ Nicolás Cabrera 13-15, Cantoblanco, Madrid, Madrid, 28049, Spain
Venue&Time: Grey Room 1

SPS Journal Club: 'Probing the Rigidity of String Theory'
2025-10-16 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
Speaker: Georgina Staudt (Max Planck Institute Munich)

Venue&Time: Red Room / 12:00

Abstract: We investigate the deformability of the Veneziano amplitude. If string theory is the unique theory of quantum gravity, the tree level amplitudes of weak coupling limits should be non-deformable. We make progress in this direction for tachyon-free superstring theories by deriving a general positivity bound and excluding some specific families of deformations.

DIFT Colloquium: 'Gamma Ray Bursts, Cosmic Rays and the Sociology of Science'
2025-10-16 15:30 - 17:00 | AULA POLIVALENTE UAM, Plaza Mayor Campus de Cantoblanco UAM. C. Einstein, 7, Fuencarral-El Pardo, 28049 Madrid, Madrid, Madrid, 28049,, Spain
Speaker: Álvaro de Rújula from IFT & CERN

Venue & Time: Aula Polivalente UAM
Abstract:
Gamma-Ray Bursts (GRBs) and Cosmic Rays (CRs) are not difficult to comprehend. Quasars and micro-quasars are seen to emit highly relativistic “Cannonballs” (CBs), though the underlying mechanism remains unfathomable. The observation that core-collapse supernovae also emit CBs —plus some trivial relativistic kinematics— provides a successful understanding of GRBs and CRs. The self-defined “official experts” on these fields resist the evidence, in an explicitly inquisitorial way.

This colloquium is related to the I+D+i project whose reference is CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033. The topic is framed within the following research line: Origin and composition of the universe: Astroparticles and Cosmology (Astro/Cosmo).

Old Journal Club: 'Renormalization and Effective Lagrangians'
2025-10-16 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Pau Garcia Romeu (IFT) will present Renormalization and Effective Lagrangians by Joseph Polchinski.

Venue&Time: Blue Room / 17:00

Abstract:

There is a strong intuitive understanding of renormalization, due to Wilson, in terms of the scaling of effective lagrangians. We show that this can be made the basis for a proof of perturbative renormalization. We first study renormalizability in the language of renormalization group flows for a toy renormalization group equation. We then derive an exact renormalization group equation for a four-dimensional λø 4 theory with a momentum cutoff. We organize the cutoff dependence of the effective lagrangian into relevant and irrelevant parts, and derive a linear equation for the irrelevant part. A lengthy but straightforward argument establishes that the piece identified as irrelevant actually is so in perturbation theory. This implies renormalizability. The method extends immediately to any system in which a momentum-space cutoff can be used, but the principle is more general and should apply for any physical cutoff. Neither Weinberg’s theorem nor arguments based on the topology of graphs are needed.

More info: https://inspirehep.net/literature/189574

Pheno Journal Club: Coherently enhanced decoherence and cloud substructure of atom interferometers
2025-10-21 15:00 - 16:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Pablo Blanco Mas (IFT)

Venue & Time: Grey Room 3 / 15:00

Abstract: We study how coherent scattering of a background gas off an atom (or other matter) interferometer can lead to enhanced signals from phase shifts and contrast loss. We focus on the inclusion of realistic features of atom interferometers such as finite temperature, cloud substructure, and time-dependent cloud radii. The inclusion of these effects, extending beyond the previously considered point-like cloud approximation, naturally allow us to study the smooth transition between the coherent and incoherent scattering regimes. We discuss how the formalism presented herein can be tested in the laboratory (with near-infrared photons or an eV-scale electron gun), and discuss an application for the detection of dark matter interacting via long-range forces.

SPS Journal Club: Inflationary Particle Production and the Swampland
2025-10-23 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
Speaker: Joaquin Masias (Munich, Max Planck Institute)
Venue&Time: Red Room / 12:00 PM
Abstract: TBA

Bubble wall dynamics from nonequilibrium quantum field theory
2025-10-23 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
Speaker: Matthias Carosi from Munich, Tech. U.

Venue & Time: Red Room / 15:00

Abstract:

First-order phase transitions in the early universe are a unique probe of physics beyond the Standard Model, with potential implications for electroweak baryogenesis, the formation of primordial black holes, magnetogenesis and the production of dark matter. Upcoming gravitational wave detectors may capture the imprint of such transitions, but to extract theoretical insights from these signals requires a precise understanding of the underlyingdynamics.
In this talk, I show how the language of nonequilibrium quantum field theory, combined with the two-particle-irreducible effective action, provides anatural framework for describing the dynamics of a bubble after nucleation. After a brief introduction to the closed-time-path formalism, I derive the dynamical equations governing the bubble and the plasma, and identify all sources of friction for thebubble expansion. This framework unifies the pre-existing approaches within a single, consistent description. In the ultrarelativistic regime, I demonstrate how to compute the friction induced by the pair production of heavy scalar particles and outline the contributions of particle mixing andtransition radiation.

Recent results on the origin of Galactic CRs from gamma-ray astronomy
2025-10-27 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
Speaker: Guillem Martí-Davesa (INFN-Trieste)

Venue&Time: Red Room / 15:00

Abstract: Supernovae have traditionally been invoked as the dominant cosmic ray factories within our Galaxy, capable of accelerating protons up to PeV energies. In this seminar we will discuss to what extent such a view holds today, and if alternative source populations could instead be relevant actors. Thus, a comprehensive review of recent findings on supernovae, stellar clusters, and microquasars will be presented, with particular emphasis on observational signatures above GeV energies.

Seminar: 'Entanglement asymmetry and spontaneously broken symmetries'
2025-10-28 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
Speaker: Eduardo García-Valdecasas (SISSA, Trieste)
Venue&Time: Red Room / 15:00
Abstract: Entanglement asymmetry is a relative entropy that faithfully measures the breaking of a symmetry in a subregion. We explore some applications in theories with spontaneously broken higher form symmetries. We will start with discrete abelian symmetries and then discuss continuous symmetries. We will be able to recover the Mermin-Wagner-Coleman theorem and refine it for the case of subregions.

Pheno Journal Club
2025-10-28 15:00 - 16:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Every Tuesday at 15:00 in Grey Room 3.

Quantum Information Journal Club: Randomized truncation
2025-10-29 11:30 - 12:30 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Aram Harrow (MIT)
Venue&Time: Grey Room 3 / 11:30
Abstract: Given a vector v, what is the closest k-sparse vector? The answer to this question is usually that we should take the largest k entries of v. It turns out that we can do better with randomized approximations. When approximating pure bipartite entangled states with states of low Schmidt rank, this means that mixed approximations outperform pure approximations. This fact has application to classical algorithms for matrix product states by improving the truncation step, and to quantum algorithms for Hamiltonian simulation.
Joint work with Angus Lowe and Freek Witteveen.
https://arxiv.org/abs/2510.08518

SPS Journal Club: Weak Gravity and Perturbative Black Holes
2025-10-30 12:00 - 13:00
Speaker: Matteo Lotito (IFT)
Venue&Time: Red Room / 12:00
Abstract:
I present a brief summary of the derivation of the Weak Gravity Conjecture within perturbative string theory, following [2403.14449], and highlight possible gaps that may hinder a fully consistent proof. I then analyze the existence and properties of the black hole solutions whose extremality bounds are compared to the string spectrum in the statement of the WGC. This analysis demonstrates that the black hole solutions we employ in our setup are reliable and do not undermine the validity of our results.

Old Journal Club: Neutrino Masses and Mixings in Gauge Models with Spontaneous Parity Violation
2025-10-30 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Pablo Blanco (IFT) will present Neutrino Masses and Mixings in Gauge Models with Spontaneous Parity Violation de Rabindra N. Mohapatra, Goran Senjanovic, Jul, 1980 Phys.Rev.D 23 (1981) 165.
Abstract:
Unified electroweak gauge theories based on the gauge group SU(2)L×SU(2)R×U(1)B−L, in which the breakdown of parity invariance is spontaneous, lead most naturally to a massive neutrino. Assuming the neutrino to be a Majorana particle, we show that smallness of its mass can be understood as a result of the observed maximality of parity violation in low-energy weak interactions. This result is shown to be independent of the number of generations and unaffected by renormalization effects. Phenomenological consequences of this model at low energies are studied. Observation of neutrinoless double-β decay will provide a crucial test of this class of models. Implications for rare decays such as μ→eγ, μ→eee¯, etc. are also noted. It is pointed out that in the realm of neutral-current phenomena, departure from the predictions of the standard model for polarized-electron-hadron scattering, forward-backward asymmetry in e+e−→μ+μ−, and neutrino interactions has a universal character and may be therefore used as a test of the model.

Top Ten Foundational Ideas of Theoretical Physics
2025-11-03 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
Speaker: Anthony Zee from Kavli Institute for Theoretical Physics and the Departmentof Physics, University of California, Santa Barbara, CA, USA

Venue&Time: Red Room / 3:00 PM

Abstract:

I will list and discuss the ten foundational ideas of theoretical physics. The lecture is based on a popular book with the same title published by Princeton University Press on June 17, 2025. The book is meant to provide a sweeping overview of theoretical physics rather than a morass of details, and thus this talk may be suitable, not only for students of physics, but also for those who are interested in theoretical physics but do not know much about it.

10th IBS/IFT workshop: Dark World to the Swampland
2025-11-04 09:00 - 2025-11-07 19:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
The IBS-IFT Workshop is a regular event organized jointly by IFT and IBS-CTPU, this year reaching its tenth anniversary.
The aim of the workshop is share ideas, foster collaborations, and to discuss recent developments in theoretical physics.
The event is organized over two weeks. The first week, November 4-7, will focus on String Phenomenology
The Center for Theoretical Physics of the Universe is one of the 30 centers of the Institute of Basic Science in South Korea. The IBS-CTPU carries out research on particle physics and cosmology, which aims to understand nature at the most fundamental level and answer the big questions about the origin of the universe.
The Institute for Theoretical Physics IFT UAM-CSIC is a joint research center belonging to the Spanish National Research Council (CSIC) and the Universidad Autónoma de Madrid (UAM). It is the only Spanish center dedicated entirely to research in Theoretical Physics. The IFT members develop research in the frontiers of Elementary Particle Physics, Astroparticles, and Cosmology, in order to understand the fundamental keys of Nature and the Universe.
With this workshop we want to try to advance our understanding of quantum gravity, mainly through the swampland program, by refining several of the conjectures that have been put forth in the program to bridge the gap between effective field theories and the UV completion as quantum gravity.

HoloClub: 'N=1 Supergravity from Super Virasoro TQFT'
2025-11-04 11:30 - 13:00
Speaker: Sounak Pal (Indian Institute of Technology)
Venue&Time: Grey Room 3 / 11:30
Abstract: I will discuss some aspects of 2D and 3D quantum gravity in
the language of Topological quantum field theory (TQFT). Recent
developments include calculating various gravity partition functions
in AdS3 using descriptions of Liouville conformal field theory (CFT).
We extend this formalism for the N=1 super Liouville case and use
super-Teichmüller TQFT to compute various partition functions of
different on-shell manifolds (admitting a hyperbolic metric with
constant negative Ricci scalar). I will also touch upon some aspects
of quantum chaos and ensemble holography. I will also discuss some
possible future extensions at the end.

Towards spectral bounds in 6d N=(1,0) supergravity
2025-11-04 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Seung-Joo

Venue & Time: Tuesday, Nov. 4th / 17:00

Abstract: In this talk we will discuss spectral bounds in 6-dimensional N=(1,0) supergravity. Specifically, considering F-theory vacua on generic base surfaces, we will constrain the U(1) vector and the tensor sectors in turn, to present explicit spectral bounds on the respective sectors. Speculations will also be made as to how the F-/string-theoretic bounds may possibly generalize to the EFT counterparts. This seminar is related to the I+D+i project whose reference is CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033. The topic is framed within the following research line: Strings and quantum gravity (Gravity/Strings).

Machine Learning for Time-Domain Astrophysics
2025-11-05 15:00 - 16:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Alex Gagliano (IAIFI/MIT)
Venue&Time: Blue Room / 3:00 PM
Abstract: The time-evolving night sky is rich with variable stars, supernovae, and merging neutron stars. Wide-field imaging surveys that monitor this variability produce gappy, multi-modal observations that demand scalable, uncertainty-aware models for physical inference. In this talk, I’ll survey my recent work in building machine learning methods for time-domain astrophysics, with a focus on learning representations of our data for classification, physical inference and the discovery of astrophysical anomalies. I’ll introduce Minuet, a compact host-galaxy image encoder trained with diffusion modeling; and a mixture-of-experts model that fuses supernova light curves and spectra while preserving modality-specific information and yielding calibrated posteriors. I’ll conclude by outlining three areas at this intersection with the greatest potential to drive discovery in the coming years: better physical models, scalable population studies, and ML-guided survey optimization.

Machine Learning Journal Club: 'Hierarchical Simulation-Based Inference of Supernova Physics'
2025-11-06 11:00 - 12:00 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Speaker: Alex Gagliano (IAIFI/MIT)
Venue&Time: 11:00 / Grey Room 2
Absrtact: Supernovae are powered by diverse physical mechanisms such as radioactive decay, circumstellar interaction, and magnetar spin-down, but distinguishing among them from light curves alone remains a major challenge. In this talk, I’ll present a hierarchical simulation-based inference framework that jointly infers both the dominant power source and the key physical parameters of supernovae. By training conditional neural density estimators end-to-end across multiple physical models, this approach yields calibrated posteriors even in regions of strong degeneracy. I’ll highlight the model’s performance on synthetic data and outline plans to fine-tune the model for population-level studies of diverse explosion physics.

DIFT Colloquium: 'String Theory and the Dark Sector'
2025-11-06 15:30 - 17:30 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Cumrun Vafa (Harvard)

Venue & Time: Aula Polivalente, Plaza Mayor UAM / 15:30
Abstract: The dark sector — comprising dark energy and dark matter — has remained a profound mystery for decades. In this talk, I will review this subject and show how string theory naturally leads to a predictive framework for a unified dark sector. I will also discuss how these string-theoretic predictions align with exciting recent cosmological observations from the DES and DESI collaborations.

This seminar is related to the I+D+i project whose reference is CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033. The topic is framed within the following research lines:

Origin and composition of the universe: Astroparticles and Cosmology (Astro/Cosmo)
Strings and quantum gravity (Gravity/Strings)

10th IBS/MultiDark WS: Dark Matter and Axions
2025-11-10 09:00 - 2025-11-13 19:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
The IBS-MultiDark-IFT Workshop is a regular event organized jointly by MultiDark and IBS-CTPU, this year reaching its tenth anniversary.
The aim of the workshop is share ideas, foster collaborations, and to discuss recent developments in the field of axion and Dark Matter physics.
The second week, November 10-13, will focus on Dark Matter/Axions.
PROGRAM
Monday, Nov. 10:
(Chair: Alejandra)
15.15h: welcome (Sven & Miguel Angel)
15.30h: Chui-Fan Kong (CTPU/IBS)
“Testing neutrino mass origins with supernova neutrinos”
16.00h: Marina Cermeno (UPM)
“New probes of supernova axion-like particles in neutrino water Cherenkov detectors”
16.30h: coffee
(Chair: Marina)
17.00h: Mario Reig (CERN)
“Testing the heterotic string theory with the axion-photon coupling”
18.00h: reception

Tuesday, Nov. 11:
(Chair: David)
10.00h: Sven Heinemeyer (IFT)
“SUSY DM in GUTs: Fitting the LHC Excesses”
10.30h: Suruj Jyoti Das (CTPU/IBS)
“Affleck-Dine origins of Baryons, Dark Matter and Inflation”
11.00h: coffee
(Chair: Sven)
11.30h: Jose Valle (IFIC)
“Collider signatures of fermionic scotogenic dark matter”
12.00h: Iván Coarasa (UZ)
“Eight Years of Dark Matter Search at the Canfranc Underground Laboratory with ANAIS”
12.30h: Elias Lopez Asamar (IFT)
“Direct searches for dark matter in the sub-GeV regime”
13.00h: lunch
(Chair: Jose)
15.30h: Alejandra Aguirre Santaella (UV)
“New insights on low-mass dark matter subhalo tidal tracks via numerical simulations”
16.00h: David Alonso-González (IFT)
“Cornered but alive: GeV-scale thermal dark matter from dark photons”
16.30h: coffee

Wednesday, Nov. 12:
11.00h: coffee
(Chair: Mario)
11.30h: Sang Hui Im (CTPU/IBS)
“The EDM inverse problem”
12.00h: Sougata Gangly (CTPU/IBS)
“Consistent N_eff fitting in big bang nucleosynthesis analysis”
12.30h: discussion time
13.00h: lunch
(Chair: Sang Hui)
15.30h: Huayang Song (CTPU/IBS)
“Mediator-induced Decay Chains from Non-Minimal Dark Sectors and Multi-Jet Collider Signatures”
16.00h:Karen Macías Cárdenas (IFT)
“Cooling core-collapse supernovae with neutrinophilic dark sectors”
16.30h: coffee
21.00h: workshop dinner

Thursday, Nov 13
(Chair: Miguel Angel)
10.30h: Andrew Buchanan (IFT)
“High Mass Dark Matter Searches With the High Speed LMC”
11.00h: coffee
11.30h: Gaetano di Marco (IFT)
“The interconversion between gamma rays and ALP across various astrophysical environments: a new numerical approach”
12.00h: Pedro Jose de la Torre Luque (IFT)
“Multimessenger constraints for electrophilic feebly interacting particles”
12.30h: farewell

Cosmology Journal Club
2025-11-11 14:00 - 15:00

SPS Journal Club: Holographic constraints on AdS flux vacua
2025-11-13 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
Speaker: Antonia Paraskevopoulou (Munich, Max Planck Inst. and LMU Munich)
Venue & Time: Red Room / 12:00
Abstract: In this talk, I will argue that the covariant entropy bound poses non-trivial restrictions on anti-de Sitter(AdS) flux vacua. After motivating the bound on AdS, we will see how it naturally arises in the context of the supergravity equations of motion, based on some reasonable assumptions. In four dimensions, we argue that the bound suggests a lower bound on the superpotential, as we will verify in examples. Based on work in progress with N. Cribiori and T. Van Riet.

Seminar: 'BipoSH: Structured test bed for cosmic isotropy violation'
2025-11-13 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
Speaker: Tarun Souradeep (Raman Research Institute, Bengaluru, India)
Venue & Time: Red Room / 3:00 PM
Abstract: The Cosmological Principle, a fundamental tenet of the ‘standard model of cosmology’, predicates a statistically isotropic distribution of fluctuations in the measured cosmic microwave background (CMB) temperature and polarization sky maps. Enigmatic anomalies claimed in the WMAP and Planck CMB sky maps, and some other recent observations, could challenge the standard model. However, these claims need to be cast in an objective mathematical framework and established with statistical rigor. Bayesian inference of the underlying covariance structure of random fields on the sphere in the Bipolar Spherical Harmonic (BipoSH) representation, developed in our research program, provides such a framework. We review some recent inferences drawn from Planck data and discuss the future prospects with proposed CMB observations.

Colloquium: 'The Promise of Gravitational Wave Cosmology'
2025-11-17 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
Speaker: Tarun Souradeep (Raman Research Institute, India)
Venue & Time: Red Room / 3:00 PM
Abstract: The 10th anniversary of the first detection of gravitational waves (GWs) is an apt time to assess the promise of this across all GW windows to the understanding of our Universe. The talk briefly reviews the status and successes achieved. The focus will be on the promise for cosmology of the upcoming LIGO-India observatory in early 2030s, LISA space mission in mid 2030s, and the proposed next generation cosmic microwave background and terrestrial/lunar missions. This seminar is related to the I+D+i project whose reference is CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033. The topic is framed within the following research line: Origin and composition of the universe: Astroparticles and Cosmology (Astro/Cosmo).
