Instituto de Física Teórica

SPS Journal Club: 'Flux Backtracking and Decoupling of Scale Separated AdS Vacua'
2025-11-20 12:00 - 13:00 (Europe/Madrid) | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Fien Apers (IFT)
Venue & Time: Red Room / 12:00
Abstract: I will explain how the flux backtracking method (https://arxiv.org/pdf/2506.03314) can be used to reconstruct the D-brane configuration whose near-horizon region realises the DGKT vacua. As an application, I will show how this reconstructed geometry allows one to verify whether the corresponding D-brane theory decouples from bulk gravity.

Seminar: Average-case quantum complexity from glassiness
2025-11-19 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
Speaker: Alexander Zlokapa (MIT)
Venue & Time: Red Room / 11:30
Abstract: In the classical setting, glassiness characterizes many natural problems (e.g., random k-SAT) and underlies average-case hardness by obstructing a family of “stable” classical algorithms (e.g., constant-time Langevin dynamics). In this work, we develop analogous quantum results. Our techniques, based on quantum optimal transport, differ significantly from classical probabilistic approaches due to the sign problem in the absence of a known eigenbasis. We show that quantum glassiness obstructs stable quantum algorithms, including constant-time Lindbladian dynamics (even when starting from the maximally mixed state). Using the replica trick, we also find that random 3-local Pauli Hamiltonians are quantumly hard and give evidence that random k-local Hamiltonians are quantumly easy for sufficiently large constant k. This differs from the analogous classical (Ising, glassy phase for all k) and fermionic (SYK, never glassy for any k) k-local ensembles. (Talk based on arXiv:2510.08497.)

Pheno Journal Club
2025-11-18 15:00 - 16:00, 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.

Seminar: 'Quantum Field Theory, an Overview'
2025-11-18 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 (Kavli Institute for Theoretical Physics and the Department of Physics, University of California, Santa Barbara, CA, USA)
Venue & Time: Red Room / 3:00 PM
Abstract: I give an overview and appreciation of quantum field theory, the most precisely tested theory in physics. The talk is addressed to those without any knowledge of quantum field theory. It is based on my textbook Quantum Field Theory in a Nutshell and my semi-popular book Quantum Field Theory, as Simply as Possible (both published by Princeton University Press.)

Cosmology Journal Club
2025-11-18 14:00 - 15:00, 2025-11-04 14:00 - 15:00, 2025-10-28 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.

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).

Charla abierta: 'Los fundamentos invisibles de la naturaleza'
2025-11-15 11:00 - 12:00
En 2025 celebramos el centenario de la mecánica cuántica, una revolución científica que transformó nuestra visión del mundo al revelar que, en lo más profundo de la naturaleza, rigen leyes desconcertantes, como el efecto túnel, el principio de incertidumbre, la superposición, el entrelazamiento… A través de esta charla divulgativa descubriremos la ciencia de los universos paralelos o las realidades superpuestas y veremos cómo la mecánica cuántica impacta en nuestra vida cotidiana: microchips, láseres o resonancias magnéticas, además de ordenadores cuánticos que se están construyendo hoy en día. ¿Qué nos depara el futuro próximo? Acércate y alucina.
Se trata de una actividad divulgativa para acercar la física cuántica al público general, combinando ciencia, reflexión y naturaleza. Incluye la charla ‘100 años de física cuántica: los fundamentos invisibles de la naturaleza’ por Alberto Casas, investigador Instituto de Física Teórica y Profesor de Investigación del CSIC.
Información práctica
Personal participante: Alberto Casas, investigador Instituto de Física Teórica y Profesor de Investigación del CSIC
A quién va dirigido: público general a partir de 14 años.
Aforo: 120
Lugar: Real Jardín Botánico-CSIC. Plaza de Murillo 2, Madrid.
Acceso movilidad reducida: sí
Inscripciones*: a través del siguiente formulario.
*El día de la actividad, la charla tendrá acceso libre hasta completar aforo.

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.

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.

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

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

Ciclo de Charlas IFT + Residencia: 'Física fundamental en clave cuántica'
2025-11-06 18:00 - 2025-11-15 21:00 | Residencia de Estudiantes, C. del Pinar, 21-23, Chamartín, Madrid, Madrid, 28006, Spain
Con motivo del Año Internacional de la Cuántica, el Instituto de Física Teórica (IFT, UAM-CSIC) celebra una nueva edición de su ya tradicional Ciclo de Conferencias de Física Fundamental en la Residencia de Estudiantes. A lo largo de cuatro jornadas, investigadoras e investigadores del IFT, junto a figuras internacionales invitadas, abordarán el papel central que juega la física cuántica en nuestra comprensión del universo. Desde la computación cuántica hasta la teoría de cuerdas, pasando por los aceleradores de partículas y las conexiones inesperadas entre la física y el arte, el ciclo ofrecerá al público general una panorámica actualizada de la investigación física más avanzada.
Fechas: 6, 7, 13 y 14 de noviembre de 2025
PROGRAMA
Jueves, 6 de noviembre
18:00 | Álvaro M. Alhambra (IFT UAM-CSIC): “Computación cuántica, perspectivas de futuro”
La computación cuántica se encuentra en un punto de inflexión: tras décadas de desarrollo teórico, los primeros dispositivos experimentales empiezan a mostrar su potencial. ¿Qué podemos esperar en los próximos años? ¿Qué problemas reales podría resolver un ordenador cuántico? En esta charla exploraremos las bases de esta nueva tecnología, los retos actuales y las perspectivas científicas y tecnológicas a medio y largo plazo.
19:30 | Mª Ángeles Pérez García (USAL): “Deconstruyendo una estrella de neutrones”
Deconstruyendo una estrella de neutrones es un viaje al corazón de uno de los objetos más extremos del universo. A partir de los restos de una supernova, estas estrellas concentran más masa que el Sol en un radio de apenas una docena de kilómetros. En este viaje buscamos “desarmarlas” conceptualmente: entender cómo la materia se comporta cuando la presión convierte los átomos en un mar de neutrones superfluidos. Combinaremos física cuántica, y gravedad para entender sus capas y procesos internos. La idea es explorar cómo estos fascinantes objetos pueden ayudarnos a descifrar los misterios del interior estelar y, en última instancia, los límites mismos de la materia.
Viernes, 7 de noviembre
18:00 | Cumrun Vafa (Harvard): “Puzzles para descifrar el universo”
Debajo de todas las complejas y formidables estructuras matemáticas que formulan las leyes físicas, descansan simples pero profundas verdades. Son por estas verdades sencillas, y no por los detalles técnicos complicados, por lo que se esfuerzan los científicos cuando tratan de desvelar las leyes de la naturaleza. Afortunadamente, estas ideas clave pueden ilustrarse a menudo con sencillos puzles matemáticos (rompecabezas, acertijos,…). En esta charla expondré varios ejemplos de estos sencillos puzles y mostraré cómo pueden arrojar luz sobre algunos de los conceptos más profundos de la física. Además, se pedirá a los asistentes que participen en la resolución de los puzzles durante la charla, que será muy interactiva. Está basada en mi libro “La Simplicidad del Universo” (“Puzzles to Unravel the Universe”, en la versión original), dirigido al público en general y que no requiere tener amplios conocimientos de matemáticas o física, sólo un mínimo de curiosidad.
Esta charla se desarrollará en inglés y contará con un equipo de traducción simultánea.
Jueves, 13 de noviembre
18:00 | Ángel M. Uranga (IFT UAM-CSIC): “1000 maneras cuánticas de destruir el universo”.
Vivimos en un universo que parece estable… pero ¿y si solo lo fuera por ahora? Las leyes cuánticas permiten escenarios tan exóticos como inquietantes: desde la desintegración del vacío debido a inestabilidades en el campo de Higgs, hasta procesos más profundos que podrían surgir de una teoría aún incompleta de la gravedad cuántica. En esta charla exploraremos algunos de estos mecanismos hipotéticos —pero físicamente plausibles— que podrían, en última instancia, provocar el colapso del universo tal y como lo conocemos.
19:30 | Ana Cueto (UAM): “El futuro de la cuántica en los grandes aceleradores”
¿Qué papel jugará la física cuántica en la próxima generación de aceleradores de partículas? Con instalaciones como el LHC y sus sucesores, las tecnologías que estudian la estructura de la materia entran en una nueva era. Esta charla analizará qué descubrimientos podríamos tener en el horizonte.
Viernes, 14 de noviembre
19:00 | Esperanza López (IFT UAM-CSIC): “Música y experiencias cuánticas”
La física cuántica ha transformado nuestra visión del mundo, y su belleza abstracta ha inspirado otras disciplinas, como la música. En esta charla singular, exploraremos los vínculos y paralelismos entre la experiencia estética y el asombro científico.
Con la colaboración de los siguientes artistas:
Miguel Álvarez-Fernández: Artista sonoro, compositor, musicólogo y ensayista de reconocido prestigio. Desde 2008 dirige y presenta el programa Ars Sonora en Radio Clásica.
Alvaro Pérez: Saxofonista y compositor. Reconocida figura del Jazz y la improvisación, con una extensa discografía. Ha tocado con varias orquestas, incluyendo la de RTVE como solista.
Roberto Jabonero: Violinista y productor musical. Ha formado parte de importantes agrupaciones de clásica y moderno del panorama español. Es director de la Escuela de Música de Tres Cantos.
Bruno Dozza: Autor de obras de cámara, sinfónicas y escénicas estrenadas en festivales y salas en Europa, Asia y Estados Unidos. Ha colaborado con destacados artistas internacionales.
Carlos de la Blanca: reconocido y joven pianista. Ha dado numerosos recitales en tanto en España como en el extranjero. Ha sido premiado en varios concursos nacionales e internacionales en España.

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)

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.

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.

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).

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.

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.

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.

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.

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.

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

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.

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.

Axion Physics
2025-10-24 11:00 - 13:00 | Gray Room 1, Instituto de Física Teórica, C/ Nicolás Cabrera 13-15, Cantoblanco, Madrid, Madrid, 28049, Spain
Speaker: Giovanni Villadoro from ICTP

Venue&Time: Grey Room 1 / 11:00

Abstract: Recent years have seen an increased interest in the phenomenology of the QCD axion and axion dark matter. In this lecture, I will review astrophysical and experimental bounds on axions, as well as the basics of axion detection experiments. 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: Particle Physics in the Standard Model and Beyond (BSM).

Old Journal Club: S. W. Hawking, Black holes and thermodynamics
2025-10-23 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Christian Aoufia (IFT) will present S. W. Hawking, Black holes and thermodynamics, Phys. Rev. D, vol. 13, no. 2, pp. 191–197, 1976. doi: 10.1103/PhysRevD.13.191

Venue & Time: Blue Room / 17:00

Abstract:

The concept of entropy is examined with an eye toward gaining insight into the nature of black-hole thermodynamics. Definitions of entropy are given for ordinary classical and quantum-mechanical systems which lead to plausibility arguments for the ordinary laws of thermodynamics. The treatment of entropy for a classical system is in the spirit of the information-theory viewpoint, but by explicitly incorporating the coarse-grained observable into the definition of entropy, we eliminate any nonobjective features. The definition of entropy for a quantum-mechanical system is new, but directly parallels the classical treatment. We then apply these ideas to a self-gravitating quantum system which contains a black hole. Under some assumptions—which, although nontrivial, are by no means exotic—about the nature of such a system, it is seen that the same plausibility arguments which lead to the ordinary laws of thermodynamics for ordinary systems now lead to the laws of black-hole mechanics, including the generalised second law of thermodynamics. Thus, it appears perfectly plausible that black-hole thermodynamics is nothing more than ordinary thermodynamics applied to a self-gravitating quantum system.

More info: https://inspirehep.net/literature/113269

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.
