PhD dissertation: Quantum Information & its interplay with High-energy Physics
2025-09-26 10:00 - 11:30 (Europe/Madrid) | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Alexander Bernal (IFT) PhD dissertation.
Supervisor: Alberto Casas & Jesús Moreno
Venue&Time: ¨Blue Room / 10:00 AM
Abstract:
This thesis explores the intersection of Quantum Information Theory (QIT) and High-Energy Physics. We demonstrate the presence of entanglement and Bell nonlocality in vector boson systems resulting from scalar and pseudoscalar particle decays, focusing on the H→ZZ process and generalizing to broader Lorentz-invariant scenarios. We also develop a method for quantum state tomography through angular distributions in scattering processes. Beyond high-energy applications, the thesis contributes to the field of QIT by providing new tools for studying genuine multipartite entanglement, exploring CHSH nonlocality violation in hybrid systems, and introducing operational definitions for fundamental concepts like quantum dimensionality and classicality. These latter results connect with core ideas in QIT such as the accessible information, the joint measurability, and the quantum steering.

To bind or not to bind, a tale of two nucleons
2025-09-26 11:30 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: André Walker-Loud (LBNL)
Venue&Time: Red Room / 11:30 AM
Abstract: Our ability to understand the emergence of nuclear physics from the Standard Model requires an understanding two nucleon interactions from the underlying quark and gluon degrees of freedom. Due to the non-perturbative nature of QCD at low-energies, the only method to provide such predictions, with quantifiable uncertainties is lattice QCD. Yet the application of lattice QCD to the two-nucleon problem is beset by a number of significant challenges, such that it has remained uncertain whether di-nucleon systems form bound states at pion masses heavier than nature. I will present recent work exploring this question with all varieties of methods in the literature, including the HAL QCD potential method, on a single set of gauge ensembles, enabling for a direct comparison of the methods.

Delta N formalism: non-linear evolution of scalar and tensor perturbations during inflation
2025-09-26 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: Danilo Artigas

Institution: Kyoto University

Location&Place: IFT Seminar Room/Red Room

Abstract:

Linear-perturbation theory has proven to be an extremely powerful tool to compare inflationary models with observational data. Recently, the newcoming high-precision observations call for predictions beyond linear perturbations. Such effects are known to be relevant for example in the production of primordial black holes or scalar-induced gravitational waves. The delta N formalism proposes to capture some of these non-linearities by describing the universe as a set of homogeneous patches evolving independently. After reviewing its formulation, I will apply it to the case of a single scalar field following a slow-roll evolution, briefly interrupted by a phase of ultra-slow roll where the potential is nearly flat. Taking care of the correlation of the patches, I will show how to obtain correlation functions of scalar perturbations. As a final note, I will briefly show how this procedure can also be applied to describe primordial gravitational waves.

El CSIC te llama esta noche: Noche Europea de los Investigadores y las Investigadoras 2025
2025-09-26 16:00 - 20:00
El IFT coorganiza la feria científica junto con el resto de centros de investigación CSIC del campus de Cantoblanco.
Habrá diversos talleres educativos, Escape Road de mujeres Nobel y talent show científico.
El evento se celebrará el 26 de septiembre en el Espacio Fundación Telefónica, en horario de mañana para público escolar y a partir de las 16:30 para público general.

La Noche Europea de los Investigadores y las Investigadoras de Madrid (NIGHTMADRID) es un macroevento de divulgación científica en el que investigadores e investigadoras de todas las áreas de conocimiento sacan su ciencia a la calle para que la sociedad la conozca.
Para este 2025, los centros del Consejo Superior de Investigaciones Científicas (CSIC) en Cantoblanco nos desplazamos hasta Espacio Fundación Telefónica para, durante todo el 26 de septiembre, mostrar la ciencia más interesante (y, sí, divertida) que hacemos.

Vídeo realizado por: Jennifer Palencia & Laura Marcos
La actividad, totalmente gratuita, se divide en:
Por la mañana: feria de ciencia para Primaria, ESO, Bachillerato y Formación Profesional
Durante toda la mañana celebraremos una gran feria de ciencia en espacios diferenciados para Primaria y Secundaria. En el menú, que puedes consultar completo en este enlace, tendremos nuestro famoso ‘Carrito de la Ciencia’, exploraremos los secretos del vidrio y las cerámicas, jugaremos con catalizadores, pilas de hidrógeno y tabla periódica y comprobaremos en nuestras manos el poder antioxidante de la fruta.
Por supuesto, no faltará nuestro Escape Road: a la búsqueda de mujeres Nobel y no Nobel. En esta yincana el alumnado se divertirá jugando mientras aprende el nombre, los trabajos y la historia de grandes científicas de todo el mundo.
Este año, como gran novedad, el alumnado de Secundaria asistirá a la grabación en directo de un episodio del pódcast Ciencia para Leer, presentado por Carmen Guerrero, de la Vicepresidencia Adjunta de Cultura Científica del CSIC.
La reserva de plazas se realizará a partir del 15 de septiembre a las 9AM en este enlace. Habrá 80 sitios para Primaria (VER PROGRAMA AQUÍ) y 130 para Secundaria (VER PROGRAMA AQUÍ). Puedes leer la descripción de todos los talleres en este enlace.
Por la tarde: talleres exclusivos, feria de ciencia y ‘talent show científico’ para todos los públicos
A las 16:00 horas abrimos puertas de Espacio Fundación Telefónica y os invitamos a haceros con vuestro PASAPORTE CIENTÍFICO, que este año dará especial protagonismo al Año Internacional de la Ciencia y la Tecnología Cuánticas 2025 (IYQ 2025). En la entrada os daremos un pasaporte que tendréis que ir completando con pegatinas mientras pasáis por todos los centros que formamos parte del evento: por cada actividad, recibiréis una pegatina que tendréis que ir colocando en el pasaporte (en el orden que prefiráis) para recibir un regalo final.
Habrá…

Feria de ciencia con demostraciones científicas de prácticamente todas las áreas de conocimiento
Talleres a puerta cerrada para explorar mundos diversos: biología, matemáticas, física e incluso un cuentacuentos infantil.
Talent show: si en 2024 las risas estuvieron presentes en el concurso de monólogos, este año doblamos la apuesta con un concurso de talentos en el que habrá humor y arte en todas sus formas. Habrá dos pases horarios: uno a las 17.15 o otro a las 18.20
Concierto: cerraremos el evento con un concierto de Las Biolocas, que versionarán los ‘temazos’ de ayer y hoy con letras biológicas.

Programa completo: los talleres comenzarán a las 16.30. Puedes conocerlos en este enlace
Descripción de talleres y actividades: aquí.

El IFT ofrecerá un taller para ‘ver lo invisible’ y la creación de una obra de arte en directo
El Instituto de Física Teórica (IFT UAM-CSIC) ofrecerá una experiencia a puerta cerrada llamado ‘A la caza de las partículas’. En el taller, los participantes podrán “ver” las partículas que nos rodean gracias al dispositivo MiniPIX EDU, una cámara de radiación miniaturizada equipada con un detector Timepix. Este sensor es capaz de registrar la huella que dejan distintas partículas (como electrones, protones, partículas alfa o la radiación cósmica) al atravesar el detector, generando imágenes y patrones únicos. De esta manera, el público podrá observar directamente cómo se manifiestan las partículas elementales en tiempo real, comprendiendo mejor su presencia constante en el entorno. Además, se analizarán las trazas registradas para identificar diferentes tipos de partículas. El taller será impartido por investigadores del IFT, entre ellos Ernesto Arganda y Carlos Pena.
Por su parte, como parte del talent show, Juan García-Bellido, investigador IFT, ofrecerá una performance artística titulada: ‘La emision de ondas gravitatorias por una binaria de estrellas de neutrones‘, que consistirá en la producción de una obra pictórica en directo, acompañada de una explicación divulgativa de su contenido. El jurado estará compuesto por Carmen Guerrero (Cultura Científica en el CSIC), la monologuista Ana Bravo, y los ganadores de la edición del año pasado, entre ellos, la investigadora predoctoral del IFT Carmen Gómez Fayrén, que se alzó con el trofeo a mejor monologuista en 2024.

Quiénes somos
Actividad organizada por los centros del CSIC en el Campus de Cantoblanco de la Universidad Autónoma de Madrid: Instituto de Ciencia de Materiales de Madrid (ICMM) (coordinador), Instituto de Catálisis y Petroleoquímica (ICP), Centro Nacional de Biotecnología (CNB), Instituto de Investigación en Ciencias de la Alimentación (CIAL), Instituto de Cerámica y Vidrio (ICV), Instituto de Ciencias Matemáticas (ICMAT), Instituto de Física Teórica (IFT), Instituto de Micro y Nanotecnología (IMN), Centro de Biología Molecular (CBM), Instituto de Investigaciones Biomédicas Sols-Morreale (IIBM).
NIGHTMADRID es un proyecto de divulgación científica, coordinado por la Fundación madri+d y financiado por la Unión Europea dentro del Programa Horizonte Europa, bajo las acciones Marie Skłodowska-Curie con el acuerdo de subvención nº 101.162.110.
Financiado por la Unión Europea. Las opiniones y puntos de vista expresados solo comprometen a su(s) autor(es) y no reflejan necesariamente los de la Unión Europea o los de la European Research Executive Agency (EREA). Ni la Unión Europea ni la EREA pueden ser considerados responsables de ellos.

LHC Working Group on Forward Physics and Diffraction
2025-09-29 09:00 - 2025-10-02 18:30 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
The September 29-October 2 2025 four-day workshop in Madrid of the LHC Physics Centre at CERN (LPCC) Forward Physics Working Group provides a forum at CERN for experimental collaborations and theorists to meet and exchange latest results across all topics of forward physics at the LHC.
The workshop will take place at the Institute of Theoretical Physics (Campus de Cantoblanco 28049 Madrid Spain) and we will be hosted by Prof. Agustin Sabio Vera. To come to IFT, you can take Line C-4 (Colmenar Viejo or Alcobendas/San Sebastián de los Reyes), that takes you to the University (Cantoblanco-Universidad Station). You can pick it up in Atocha (main station in the Centre/South of Madrid), Nuevos Ministerios (Paseo de la Castellana) and Chamartín (main station in the North). After Chamartín, the second station is Cantoblanco-Universidad, where you should exit.
More info.

Muon g-2: nuts and bolts and lattice QCD
2025-09-29 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: Andreas Kronfeld (Fermilab)
Venue&Time: Red Room / 3:00 PM
Abstract: This seminar consists of two parts. First, it is discussed how various approaches to the hadronic vacuum polarization (HVP) for the anomalous magnetic moment of the muon, g-2, are connected. Second, results for the HVP from lattice QCD are presented, focusing on the work of the Fermilab Lattice, HPQCD, and MILC collaborations.

Seminar by Roberto Vega-Morales
2025-09-29 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: Roberto Vega-Morales from Granada U.

Venue&Time: Red Room / 3:00 PM

Abstract: TBA

SPS Journal Club: 'Landau-Ginzburg Models and Flux Vacua'
2025-10-02 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: Muthusamy Rajaguru (IFT Madrid)

Venue&Time: Red Room / 12:00 PM

Abstract: In this talk, I will give an overview of recent progress that has been made in constructing non-geometric flux vacua. In particular, I will focus on type IIB string compactifications where the internal geometry is described by the 2^6 and 1^9 Landau-Ginzburg (LG) models. These LG models have no Kähler moduli and allow us to realize GKP-type vacua explicitly in the interior of the complex structure moduli space. I will summarize the properties of these vacua and their implications for certain Swampland conjectures.

Relevant literature – 2503.16599, 2407.16756, 2407.16758, 2406.03435, 2306.15714, 2203.15818

Fast inference for slow likelihoods with probabilistic machine-learning
2025-10-02 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: Jesús Torrado from IEM-CSIC

Venue&Time: Red Room / 3:00 PM

Abstract: Inference for slow likelihoods can require weeks or months, if possible at all, with traditional Monte Carlo samplers. This would be the case, for example, when fitting expensive non-linear matter spectrum models, or when characterizing individual long-duration GW events. I will introduce a fast machine-learning Bayesian inference algorithm for general non-Gaussian posteriors with a moderate number of parameters. I will present a pedagogical discussion of some general aspects of it, such as dealing with the curse of dimensionality, characterizing a region of interest, or parallelising active learning. I will show that the total number of expensive likelihood evaluations can be reduced by at least two orders of magnitude compared to traditional Monte Carlo methods, at low overhead costs and no pre-training. I will demonstrate its performance on a couple of real cosmological and GW problems.

César Gómez (1954–2025): A rich life in theory
2025-10-03 10:00 - 17:30 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Venue&Time: Blue Room / 10:20 – 17:30
More info: workshops.ift.uam-csic.es/CesarGathering/
César Gómez, whose profound contributions to gauge theory, string theory and quantum gravity were matched by his vision and generosity, passed away on 7 April 2025. After earning his PhD in Salamanca, he held positions at Harvard, the IAS and CERN before joining the CSIC in Madrid, where he became a founding member of the Instituto de Física Teórica, his true scientific home.
His career spanned key areas of theoretical physics: from the quantum vacuum in QCD and two-dimensional conformal field theory to holography, black holes and the quantum structure of spacetime. In recent years he embarked on bold new ideas about symmetry breaking and the quantum origin of the universe, entering one of his most creative periods when his life was cut short.
Beyond his scientific achievements, César was a gifted teacher, an inspiring presence at seminars and a remarkable conversationalist. He leaves behind not only a lasting scientific legacy, but also the memory of a colleague and friend who enriched every exchange with curiosity, insight and humanity.
The meeting will be an opportunity to celebrate Cesar’s life and career through the personal recollections of some of his friends and collaborators.
Read CERN’s obituary

Cosmology Journal Club
2025-10-07 14:00 - 15:00, 2025-10-14 14:00 - 15:00, 2025-10-21 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.

Dragon School: cosmic-ray theory, phenomenology and beyond
2025-10-08 09:30 - 2025-10-10 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
This school is intended to provide an overview about a variety of topic centered around the problem of cosmic-ray transport in the Galaxy and non-thermal diffuse emissions. We will provide both dedicated seminars and hands-on sessions on the modeling and computation of cosmic-ray propagation and the correlated non-thermal emissions in different astrophysical environments. In particular, the event will feature a detailed presentation of the state-of-the-art theoretical and numerical tools to calculate relevant astro-particle quantities (production of gamma-ray, radio or neutrino emission, as well as the signals produced by dark matter), especially focused on the broad applicability of the DRAGON2 code.
This event will be held at the Institute of Theoretical Physics in Madrid (Spain) from October 8th to October 10th 2025. The organizing committee of the workshop will be composed by the current main developers of the code: Daniele Gaggero (researcher at INFN Pisa), Silvio Sergio Cerri (researcher at Lagrange Laboratory – Observatoire Côte d’Azur, in Nice) and Pedro De la Torre Luque (Juan de la Cierva postdoc at UAM and IFT), along with Miguel Ángel Sánchez-Conde (associate professor at UAM and IFT).
The school will have a duration of three days, in which the first two days will be dedicated to lectures (during the morning), covering cosmic-ray related physics (astrophysical plasmas, particle interactions, computational techniques, etc) and discussing the status of current observations of Galactic diffuse emissions (radio, X-ray, neutrino and gamma-ray diffuse backgrounds) and hands-on sessions (during he afternoon), while the third day will be dedicated to a number of invited talks about the use of diffuse emissions for indirect dark matter searches and the DRAGON2 code beyond the study of cosmic-ray propagation.
SEMINARS:
Miércoles 08/10/25 a las 15:30h
Speaker: Manuel Rocamora
Title: “Propagation of cosmic rays and production non-thermal radiations with DRAGON and Hermes”
Abstract: Cosmic-ray measurements have reached unprecented precision in the last decade. These observations are challenging our standard intepretation of how cosmic rays generated and how they propagate in the Galaxy. Therefore, it is crucial to achieve accurate predictions to understand the origin of discrepancies with data. On top of this, these predictions allow us to infer the non-thermal radiations that cosmic rays produce when they interact with Galactic magnetic fields, radiation fields and gas. This session is dedicated to provide a detailed overview of the DRAGON and Hermes codes and how they can be used to obtain predictions of the cosmic ray, gamma-ray, neutrino and even radio diffuse Galactic fluxes that are correlated.
Jueves 09/10/25 a las 12:45h
Speaker: José Alberto Rubiño
Titulo: Diffuse radio emission
Abstract: Synchrotron emission from cosmic-ray electrons is a powerful tool for probing both the Galactic magnetic field and the energy spectrum of electrons within our Galaxy. This lecture will cover the fundamental principles of synchrotron radiation, methods for measuring this emission, and the current state of observations, with a focus on measurements in the GHz frequency range.

SPS Journal Club: Symmetric Moduli Spaces, the Swampland Distance Conjecture (...and the Emergent String Conjecture?)
2025-10-09 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: Bernardo Fraiman (IFT)

Venue&Time: Red Room / 12:00

Abstract: For non-compact, locally symmetric moduli spaces M, the set of geodesics and the geometry of the boundary can be completely characterised using group theory. Under the assumption that M is “compactifiable” and some mild conditions on the spectrum of states, we prove the SDC for all locally symmetric spaces. We show that the states necessarily transform in some representation of the local isometry group, and that the convex hull encoding the exponential rate at which the leading tower of states becomes light coincides with the convex hull of the weights of the representation.

In this talk I will discuss briefly some aspects of the proof, the domain of applicability of our assumptions and their limitations. If time permits, I will also explain how the relation between towers and weights allows one to classify moduli spaces, particle state representations and space time dimensions compatible with the Emergent String Conjecture. Based on 2508.18401 and work in progress.

Large neutrino mass in cosmology and keV sterile neutrino dark matter from a dark sector
2025-10-09 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
Speaker: Thomas Schwetz from Karlsruhe Institute of Technology (KIT)

Venue&Time: Red Room / 3:00 PM

Abstract:
Recent results from cosmology place sever upper bounds on the sum of neutrino masses, starting to be in conflict with lower bounds from neutrino oscillations. If this neutrino tension persists, it may indicate new physics in cosmology and/or neutrino physics. After a brief review of the present state, I discuss a new physics scenario able to explain this tension. It is based on an extended seesaw model for neutrino mass, including a number of massless neutrinos acting as dark radiation, as well as a keV state as a dark matter candidate. The dark sector is brought into equilibrium with neutrinos between BBN and recombination. This scenario predicts a slight increase in the effective number of neutrino species Neff at recombination, potentially detectable byfuture CMB missions.

Searching for New Physics through the Neutrino (bag)pipe
2025-10-10 11:00 - 13:30 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Daniel Naredo Tuero PhD dissertation

Searching for New Physics through the Neutrino (bag)pipe

Venue&Time: Red Room / 11:00

Abstract:
Among the many open problems that plague the Standard Model (SM) of particle physics, the massive nature of neutrinos stands out as it is one of the few indications of New Physics that we have observed in our terrestrial laboratories, as supported by the phenomenon of neutrino flavour oscillations. Neutrinos offer a rich phenomenological and complementary programme, from laboratory signals to cosmological imprints, as we will explore in this Thesis. First, we will assess the status of the cosmological neutrino mass bound in light of the latest results from DESI, identifying the features and tensions in the data that are driving this ever-tightening constraint. Second, we will consider the inclusion of heavy Majorana right-handed neutrinos, the most economical SM extension to generate neutrino masses. In particular, we will show how it is possible to constrain heavy neutrinos above the electroweak scale by harnessing their effects on precision observables. Lastly, we will investigate the role of neutrino data in the global fit of the SM Effective Field Theory (SMEFT), showing that the inclusion of neutrino oscillation and scattering data can add new valuable information.
Supervisores: Enrique Fernández-Martínez y Xabier Marcano

Holo Club: Explicit Connections Between Krylov and Nielsen Complexity
2025-10-14 11:30 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Le-Chen Qu (IFT)

Venue&Time: Grey Room 3 / 11:30

Abstract: We establish a precise correspondence between Krylov complexity and Nielsen complexity in quantum many-body systems. By identifying the Krylov basis with the generators of elementary gates in Nielsen’s geometric framework, the Krylov complexity of precursor operators acquires a geometric interpretation as the length of straight-line paths in Nielsen geometry. This construction provides an upper bound on Nielsen complexity, which becomes exact in the small-precursor limit. Employing the SYK model as a test case, we demonstrate that the straight-line trajectory satisfies the Nielsen geodesic equation and remains both locally and globally minimizing up to a critical value of $z$, beyond which conjugate points and geodesic loops arise. Within this framework, cost functions quadratic in the Krylov index are further shown to reproduce the conjectured proportionality between the complexity growth rate and the operator size.

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.

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

Open String Axiverse
2025-10-20 15:00 - 16:15 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Giovanni Villadoro from ICTP

Venue & Time: Red Room / 15:00

Abstract: Localized charged fields are a general feature of many realistic string compactifications. I will review how in four dimensions they can lead to a multitude of perturbatively-exact global symmetries that, when spontaneously broken, generate a new axiverse compatible with post-inflationary evolutions.

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.

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

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.

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.
