Instituto de Física Teórica

Polygonal Gravity Seminars
2026-01-29 11:30 - 16:30 (Europe/Madrid) | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Madrid’s Polygonal Gravity Seminar Series
Wednesday, January 29th. Blue Room (IFT)

11:30h First talk

Speaker: Robie Hennigar (U. Durham, UK)
Title: Building Regular Black Holes

Abstract: The study of regular (singularity-free) black holes has a long
history, but progress has been limited by the absence of a dynamical
framework in which they form and by conceptual issues at the kinematical
level. In this talk I will discuss recent work in which spherically
symmetric regular black holes emerge as unique solutions of gravity
theories with infinite towers of higher-curvature corrections, enabling
explicit analyses of their formation and dynamics. I will review the
construction, summarize key results, and highlight open problems.

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12:45-14:15 Lunch break

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14:30h Second talk

Speaker: Pablo Cano (U. Murcia)

Title: Amplification of new physics in the quasinormal mode spectrum of
highly-rotating black holes

Abstract: The computation of quasinormal modes of rotating black holes in
modified theories of gravity has been recently made possible thanks to the
development of new techniques, like a modified Teukolsky equation and
spectral methods. However, no method so far has been able to peek into the
highly rotating regime — close to extremality. In this talk, I will
consider a newly identified higher-curvature modification of GR that
preserves the isospectrality of quasinormal modes in the eikonal limit. In
this theory, eikonal perturbations can be described in terms of an
effective scalar equation, and solving it we will obtain the corrections
to the eikonal Kerr quasinormal modes for arbitrary rotation. For moderate
rotation, we check that the eikonal computation gives a good approximation
to the exact QNMs obtained from the modified Teukolsky equation, even for
low harmonics. For high rotation, we discover that the corrections to GR
become much larger and can lead to dramatic effects. Our results suggest
that the observation of the ringdown of a highly rotating black hole would
be a “golden event” to search for new physics.

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More information about these and following monthly seminars can be found at the webpage

SPS Journal Club: 'Mapping moduli across heterotic conifolds'
2026-01-29 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: ‘Mapping moduli across heterotic conifolds’

Speaker: Christian Aoufia (IFT)

Venue & Time: Red Room / 12:00

Abstract: In this work, we provide evidence for a duality between 4-dimensional Calabi-Yau compactifications of the heterotic string, in which the base manifolds are linked by a conifold transition. In recent work, a geometric proposal was put forward for how 5-branes and gauge bundles are carried across such transitions. It was observed that compactifications connected in this way lead to 4-dimensional effective theories with the same massless spectrum. Here we provide much stronger evidence that these heterotic conifold transitions do indeed lead to dual theories. We construct a duality map between the field spaces of the two compactifications and use it to demonstrate the agreement of large numbers of holomorphic functions appearing in the definition of the effective theories. In an example, we show that 147,440 independent superpotential Yukawa couplings agree across the duality as holomorphic functions of the moduli. In certain special cases, the putative duality studied here reduces to the target space duality of (0,2) gauged linear sigma models.

Pheno Journal Club: 'GeV-scale QCD Axion'
2026-01-29 12:00 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘GeV-scale QCD Axion’

Speaker: Thomas Steingasser (IFT)

Venue & Time: 12:00 / Gray Room 3

Abstract: In order to solve the strong CP problem, we study the possibility that the Peccei–Quinn symmetry is broken below the QCD scale. We find that a QCD axion can be above GeV, and may be among the observed η resonances. It is immune to quantum gravity corrections. The only fermion that has a U (1) Peccei–Quinn charge is the right-handed up quark. Flavor-changing neutral currents are surprisingly small, except for a possible but not necessary contribution to D0–D0 mixing. All accelerator and astrophysical limits can be evaded. The most significant constraint is the mass splitting between π± and π0. In a UV completed model, LHC can look for a dijet resonance in u ̄u,u ̄d, d ̄u channels.

Seminar by Ennio Salvioni (IFAE): 'Probing the Dark Sector with Large Scale Structure'
2026-01-29 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
Title: ‘Probing the Dark Sector with Large Scale Structure’
Speaker: Ennio Salvioni (IFAE)
Venue&Time: Red Room / 15:00
Abstract: Precision cosmology offers opportunities to test the nature of dark matter independently of any interactions with the visible sector. I will discuss how data from galaxy surveys, including the ongoing DESI and Euclid projects, can be leveraged to probe new dynamics in the dark sector. For this purpose, I will show how to extend the Effective Field Theory of Large Scale Structure to include physics beyond the Standard Model, enabling perturbative computations of the power spectrum of galaxies. The scenarios I will discuss include long-range dark matter self-interactions, and sub-components of dark matter exhibiting suppressed growth of structure, such as ultra-light axions or light thermal relics.
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).

Old Journal Club: 'Topological Quantization and Cohomology'
2026-01-29 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Gonzalo F. Casas (IFT) will present ‘Topological Quantization and Cohomology‘ by Orlando Álvarez Commun.Math.Phys. 100 (1985) 279
Abstract:
The relationships between topological charge quantization,Lagrangians and various cohomology theories are studied. A very general criterion for charge quantization is developed andapplied to various physical models. The relationship betweencohomology and homotopy is discussed.
More info: https://inspirehep.net/literature/206164

Seminar: 'F(ℓ)avoured searches: new physics in the 3rd generation'
2026-02-02 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
Title: ‘F(ℓ)avoured searches: new physics in the 3rd generation’
Speaker: Tamara Vázquez Schröder (IFAE)
Venue & Time: Red Room / 15:00

Abstract: The primary goal of the Large Hadron Collider (LHC) has been to discover the mechanism of electroweak symmetry breaking (EWSB). The discovery of the Standard Model (SM)-like Higgs boson in 2012 was the first step to achieve this. However, the underlying nature of EWSB remains unknown. Additionally, the SM cannot explain the origin of neutrino masses, the asymmetry between matter and antimatter in our universe, or the nature of dark matter and dark energy. It also cannot address important conceptual questions, such as why is the Higgs boson so light compared to the Planck scale, or what are the underlying dynamics through which the Higgs field provides masses to the fundamental particles. Even though the LHC has not discovered any Beyond the Standard Model physics, there are multiple hints in various areas of particle physics which could revolutionise our understanding of the elementary particles and the forces between them, leading to the start of a new Higgs and Flavour Era. In this talk I will dive into promising new physics models coupled preferentially to 3rd generation quarks or leptons that could address some of the shortcomings of the SM and could potentially explain some of the observed tensions in the particle physics landscape. Being potentially at the reach of the LHC collision energy, the search for these new physics signals in the multilepton final state could be the key to access a new era in particle physics exploration.
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).

Cosmology Journal Club
2026-02-03 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.

Quantum Information Journal Club: Continuous and field tensor network states
2026-02-04 11:30 - 12:30
Speaker: Albert Gasull, Leiden University

Venue & Time: Grey Room 3 / 11:30

Title: ‘Continuous and field tensor network states’
Abstract: Tensor network methods have provided us with a powerful set of tools with which to study strongly interacting many-body systems on the lattice. Understanding the limitations of this ansatz is paramount for the success of both numerical algorithms and exact analytical representations of the many-body wavefunction. In recent years, several generalizations making use of different notions of the continuum have appeared in the literature to tackle such different limitations. Firstly, continuous tensor network states (cTNS) is an ansatz that allows us to work directly in the continuum to answer questions related to quantum field theories, removing the need for sending the lattice spacing to zero in standard tensor network approaches. Secondly, field tensor network states (fTNS) aim to provide an exact tensor network approach to the analytical description of chiral gapped topological states in two spatial dimensions, such as the Laughlin wavefunction. While these states had been previously considered to be out of reach for the most prominent two dimensional tensor network, projected entangled pair states, by upgrading the virtual space of the network to an infinite dimensional one, we circumvent the previous no-go theorems to provide the first exact representations. In this talk, I will present an overview of both cTNS and fTNS. I will present the main ideas behind both generalizations and relation to quantum field theories. I will also showcase some of the applications that we are currently working on, as well as some of the problems that one encounters along the way. This talk is based on both published and ongoing work with Arkadiusz Bochniak, Germán Sierra and Ignacio Cirac.

Seminar: 'Co-Scaling and Alignment of Electric and Magnetic States'
2026-02-04 11:30 - 17:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Tom Rudelius (Durham U., Dept. of Math.)

Title: Co-Scaling and Alignment of Electric and Magnetic States

Venue & Time: Red Room / 11:30

Abstract: Towers of electrically and magnetically charged states in quantum gravity often exhibit two important properties. First, the ratio of the mass (or tension) of electrically charged states to magnetically charged states is of order g^2, which we refer to as “co-scaling.” Second, in theories of multiple gauge fields, the towers of states that exhibit co-scaling have charges that point in approximately the same direction in charge space as measured by the gauge kinetic matrix, which we refer to as “alignment.” In this talk, I present heuristic arguments for and examples of co-scaling and alignment in the string landscape, and I discuss applications to phenomenology and cosmology.

Pheno Journal Club
2026-02-05 12:00 - 13:00, 2026-02-19 12:00 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Every Thursday at 12:00 in Grey Room 3.

Strings, Pheno and the Swampland (SPS) Journal Club
2026-02-05 12:15 - 13:15 | 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 by Yushi Mura (KEK)
2026-02-05 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: ‘UV completion of extended Higgs models via the confinement of SU(2) gauge’
Speaker: Yushi Mura (KEK)
Venue & Time: Red Room / 15:00
Abstract: The extended Higgs sectors are often introduced to explain phenomena beyond the standard model. On the other hand, the existence of multiple scalar fields may cause the Landau pole below the Planck scale. Therefore, those models should be replaced by more fundamental theory at high energies. In this talk, we consider an asymptotic-free SU(2) gauge theory as a UV-completion of the extended Higgs models and assume they are the consequence of confinement of the gauge theory. We find that particle contents of various extended Higgs sectors previously proposed are deduced by each charge assignment of flavor symmetry of the fundamental fermions of the SU(2) gauge symmetry.

Old Journal Club: 'Threshold production of heavy top quarks: QCD and the Higgs boson'
2026-02-05 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Sergio Rodríguez (IFT) will present “Threshold production of heavy top quarks: QCD and the Higgs boson” by Matthew J. Strassler and Michael E. Peskin.
Abstract:
We calculate the threshold cross section for 𝑒+𝑒−→tt¯ to leading-logarithmic order in QCD, using a nonrelativistic approximation suggested by Fadin and Khoze. We study the mass range 100≤𝑚𝑡≤250 GeV, and show that the cross section is an excellent measure of α𝑠 for the lower portion of the mass range, while for a heavier top quark it is sensitive to the mass and couplings of the Higgs boson. We argue that a precise determination of 𝑚𝑡 and a measurement of Γ𝑡 are possible. We also show that nonperturbative effects are small, confirming that the tt¯ threshold is a detailed perturbative test of the standard model.
More info: https://journals.aps.org/prd/pdf/10.1103/PhysRevD.43.1500

Seminar: 'The Muon Magnetic Moment Mystery: a 20-year puzzle in high-energy physics'
2026-02-09 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: Zoltan Fodor (Penn State U.)
Venue & Time: Red Room / 15:00

Title: The Muon Magnetic Moment Mystery: a 20-year puzzle in high-energy physics
Abstract:
In the last two decades or so there have been stronger and stronger disagreements between direct measurements of the anomalous magnetic moment of the muon and the standard-model prediction. Such a large discrepancy would be a signal for an interaction or particle not present in the standard model. However, already in 2020 a lattice QCD calculation suggested a “no-tension” scenario. I report on our new lattice QCD calculation, which reduced the uncertainty of our 2020 result by about 40%. The agreement between the measured value of the anomalous magnetic moment of the muon and its theoretical predictions is an extremely impressive prove of the validity of quantum field theory –with three very different calculational frameworks for QED, EW and QCD– up to 11 digits.

Holo Club: 'Holographic fluids with higher-form symmetries'
2026-02-10 11:30 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: Holographic fluids with higher-form symmetries

Speaker: André Oliveira (Heriot-Watt University)

Venue & Time: Grey Room 3 / 11:30

Abstract: Higher-form symmetries are ubiquitous in physics. In this talk, I focus on the case where they are continuous and encode the conservation of extended objects. Applications include elasticity, superfluidity and phases of electromagnetism. Using holography, we explore effective descriptions of systems with the simplest case of a single higher-form symmetry. For energies well below temperature, these descriptions admit a (potentially extended) hydrodynamic regime. We verify this explicitly by studying AlAdS black branes charged under higher-form potentials. In particular, we compute quasinormal modes, starting with the low-density limit. Then, we focus on the bulk dual of a viscoelastic system and analyse instabilities for different equilibrium states corresponding to isotropic crystalline phases.

Cosmology Journal Club
2026-02-10 14:00 - 15:00, 2026-02-24 14:00 - 15:00 | Discussion room 5th floor, C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, Madrid, 28049, Spain

2nd EDI Training: 'Beyond law: Invisible Barriers to Women’s Access to Public Life'
2026-02-11 16:00 - 17:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Soledad Escobar Villegas
PhD in Political Science and García Pelayo Research Fellow at the Centre for Political and Constitutional Studies, Ministry of the Presidency (Spain).
Abstract: Over the last decades, Western societies has introduced significant legislative changes aimed at promoting gender equality and increasing the representation of women in decision-making positions. However, legal progress does not always translate into equal participation in practice.
This seminar will examine the gender representation gap in politics and society by distinguishing between formal legislative advances and the structural constraints and internal dynamics within political and social environments that continue to limit women’s access to the public sphere. The session will analyze patterns of underrepresentation and explore factors such as unequal career progression, workplace cultures, and informal power structures. It adopts an intersectional approach, considering not only gender but also women’s ethnic and cultural backgrounds. The aim is to encourage students to critically assess how social and institutional systems shape women’s representation.
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.

Pheno Journal Club: 'The Cosmic Neutrino Background is within Reach of Future Neutrino Telescopes'
2026-02-12 12:00 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Yuber Perez-Gonzalez (IFT) will present:

‘The Cosmic Neutrino Background is within Reach of Future Neutrino Telescopes’

Venue & Time: Gray Room 3 / 12:00

Abstract: The cosmic neutrino background (CνB) can be boosted to high energies due to scatterings with energetic cosmic rays (CRs) across cosmological scales. Previous calculations focused on neutral current incoherent and coherent elastic scatterings of cosmic-ray protons off relic neutrinos. However, charged current interactions and deep inelastic scatterings are also expected to occur, which enhances the boosted relic neutrino fluxes on Earth. Here, we compute the textit{total} diffuse boosted cosmic neutrinobackground (DBCνB) arising from CRs at all redshifts in the Universe, accounting for neutral current and charged current elastic and deep inelastic scatterings. We find that IceCube already places an upper limit on the cosmic neutrino background overdensity in cosmological scales of ~O(100−1000) at Eν=10^10 GeV, for a lightest neutrino mass of mν≳0.1 eV. We further show that IceCube-Gen2 could test O(1−10) CνB overdensities, and the combination of 10 future neutrino telescopes with similar sensitivity would allow us to test the ΛCDM expected CνB density for a lightest neutrino mass compatible with the KATRIN bound.

Based on 2601.09790.

SPS Journal Club: 'Hilltop quintessence, the LARGE Volume Scenario and varying-tension cosmic strings'
2026-02-12 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
Léo Veissière (IFT) will present:

‘Hilltop quintessence, the LARGE Volume Scenario and varying-tension cosmic strings’

Venue & Time: Red Room / 12:00

Recent observational data suggests that the dark energy equation of state parameter wDE is evolving with time, in apparent tension with the ΛCDM standard model of cosmology. Here we review these observational results, with particular emphasis on the evidence for phantom-like behaviour, for which wDE < −1. In an attempt to reproduce the data, we study a quintessence model of a single scalar field rolling down a hilltop potential, both from a UV-agnostic perspective and from a string theory point-of-view. For the latter we focus on a scalar potential derived from type IIB supergravity in the context of the LARGE Volume Scenario (LVS), and investigate the cosmological dynamics of the scalar near its maximum. Finally, we discuss whether an effective phantom behaviour can be reproduced by considering the interaction between the scalar field and cosmic strings with a time-dependent tension, while keeping the LVS scalar potential unchanged.

Old Journal Club: 'Supersymmetry and morse theory'
2026-02-12 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Chuying Wang (IFT) will present ‘Supersymmetry and morse theory’ by Edward Witten J. DIFFERENTIAL GEOMETRY 17 (1982) 661-692
Venue & Time: Blue Room / 17:00
Abstract:
It is shown that the Morse inequalities can be obtained by consideration of a certain supersymmetric quantum mechanics Hamiltonian. Some of the implications of modern ideas in mathematics for supersymmetric theories are discussed.
More info: https://projecteuclid.org/journals/journal-of-differential-geometry/volume-17/issue-4/Supersymmetry-and-Morse-theory/10.4310/jdg/1214437492.pdf

Holo-Club: 'Toward Krylov-based holography in double-scaled SYK'
2026-02-17 11:30 - 13:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Yichao Fu (GIST)

Title: Toward Krylov-based holography in double-scaled SYK

Venue & Time: Gray Room 3 / 11:30

Abstract:

Building on the duality between Krylov complexity and geodesic length in Jackiw-Teitelboim and sine-dilaton gravity, we develop a precise holographic dictionary for quantities in the Krylov subspace of the double-scaled Sachdev-Ye-Kitaev model (DSSYK). First, we demonstrate that the growth rate of Krylov state complexity corresponds to the wormhole velocity, and show that its expectation value in coherent states serves as a boundary diagnostic of firewall-like structures via bulk reconstruction. We also delineate an alternative bulk description in terms of the proper momentum of an infalling particle at early times, establishing a threefold duality between the Krylov complexity growth rate, wormhole velocity, and proper momentum, with clear regimes of validity. Beyond the first moments, we argue that higher-order Krylov complexities capture connected bulk contributions encoded by replica wormholes, while the logarithmic variant probes the replica saddle structure. Finally, within a third-quantized setting incorporating baby universes, we show that the Krylov entropy equals the von Neumann entropy of the parent-geometry density matrix obtained after tracing out baby universes, thereby quantifying information flow into the baby universe sector. Together, these results elevate Krylov-space observables to sharp probes of bulk dynamics and topology in ensemble-averaged 2D gravity.

Cosmology Journal Club
2026-02-17 14:00 - 15:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Quantum Information Journal Club: 'Quantum Algorithms Based on Cooling'
2026-02-18 11:30 - 12:30 | Grey Room 2, Instituto de Física Teórica, Madrid, Madrid, 28037, Spain
Date: Wednesday, February 18
Aula Gris 2 / 11:30
Speaker: Daniel Molpeceres (TU Munich)
Título: Quantum Algorithms Based on Cooling
Abstract: The purpose of this work is to study different methods for nature-inspired algorithmic cooling of physical systems, which rely on energy transfer between the system and a cool bath. These algorithms are suitable for preparation of QMB ground states, and are therefore an alternative to other well-known procedures such as variational or adiabatic algorithm, which have their own limitations. The aim of the paper is to develop this theory, and try to find in what regimes it works best, such that it can be used as an alternative or in collaboration with the previous methods. We will focus on a free-fermion model with hoppings in a 1D lattice and a certain distribution of auxiliary systems per site, try to find regimes in which the system reaches the ground state, and then extrapolate what we learn from this model into a more general noisy setting. The main questions to address are how the performance changes with the noise that may appear in an experimental setting, as well as a comparison with other methods such as adiabatic algorithm or QAOA.

PhD dissertation: 'On String Phenomenology From a Swampland Perspective'
2026-02-19 11:00 - 12:00
Author: Gonzalo F. Casas

Title: On String Phenomenology From a Swampland Perspective.

Venue & Time: Blue Room / 11:00

Abstract: This thesis investigates the deep interplay between particle physics, cosmology, and quantum gravity within the framework of string phenomenology. Focusing on Type IIA Calabi–Yau orientifolds with intersecting D6-branes, we show that the suppression of neutrino masses at infinite-distance limits necessarily entails the emergence of light towers of states. This result establishes a direct link between particle-scale physics and the geometry of extra dimensions, while also suggesting potentially testable phenomenological signatures. The thesis further connects inflationary dynamics to the quantum-gravity cutoff and examines how supersymmetry breaking in no-scale vacua can give rise to Minkowski backgrounds, offering a novel perspective on moduli stabilization.

Supervisor: Fernando Marchesano

Seminar: 'Asymmetric Dark Matter induced by Baryogenesis'
2026-02-23 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: ‘Asymmetric Dark Matter induced by Baryogenesis’
Speaker: Miguel Escudero (CERN)
Venue&Time: Red Room / 15:00
Abstract: We live in a Universe where structures are made out of baryons but not of antibaryons. Could the dark matter be made of particles and not antiparticles? This is an old question and many asymmetric dark matter scenarios have been proposed to date. Among them, the models where a dark matter asymmetry is induced from the baryon/lepton asymmetries are particularly motivated. In this seminar, I will highlight the motivations for these types of frameworks but also their challenges. I will then present a new, minimal, and predictive scenario that we developed in [2511.10731]. In this model, a dark matter asymmetry is slowly generated from the Standard Model Higgs doublet asymmetry. The scenario features two dark matter states which can lead to signals in the next generation of dark matter experiments, and we predict a new inert Higgs doublet with mass < 580 GeV which could be produced and observed at the LHC and future colliders.
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).

Seminar: Primordial black holes from Q-balls
2026-02-24 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: Shunsuke Neda (ICRR, Univ. of Tokyo)
Venue & Time: Red Room / 15:00
Title: Primordial black holes from Q-balls
Abstract:
We discuss primordial black holes (PBHs) originating from Q-balls, which are non-topological solitons arising in complex scalar field theories with a global U(1) symmetry. Depending on the cosmic expansion history, Q-balls can source PBH formation in both early matter-dominated (eMD) and radiation-dominated (RD) universes, leading to distinct phenomenological consequences.
In the eMD scenario, PBHs produced from Q-balls can account for the observed dark matter abundance, and we summarize the resulting cosmological constraints. In contrast, some scenarios of PBHs formed in a radiation-dominated universe exhibit strong PBH clustering. When motivated as seeds of supermassive black holes, their abundance and spatial distribution are observationally constrained by isocurvature perturbations. For stellar-mass PBHs relevant to LIGO-Virgo-KAGRA, we compute PBH merger rates in the presence of initial PBH clustering using updated methodologies.
This seminar illustrates how PBHs from Q-balls link particle physics models to cosmological, astrophysical, and gravitational-wave observations across multiple mass scales.

Quantum Information Journal Club: 'Generalizing the framework of translationally invariant MPS'
2026-02-25 11:30 - 12:30 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Marta Florido Llinás (MPQ)
Title: ‘Generalizing the framework of translationally invariant MPS’
Abstract: In this talk I will present our recent work on developing a canonical form for uniform matrix product states (MPS) with a boundary matrix (https://www.arxiv.org/abs/2512.11968). Starting from the standard canonical description of uniform MPS with periodic boundary conditions, I will explain how to derive a generalized canonical form for MPS with boundaries, by extending the structural analysis of matrix sets to incorporate off-diagonal blocks, and by introducing some notions inspired by formal language theory.

GRASS Seminar: 'Gravitational Duality at the Lightring, QNM isospectrality, and Ringdown Nonlinearities from Penrose Limits'
2026-02-26 11:00 - 12:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Gravity, Supergravity and Superstrings (GRASS) Seminar
Speaker: David Pereñiguez (Johns Hopkins U.)
Title: ‘Gravitational Duality at the Lightring, QNM isospectrality, and Ringdown Nonlinearities from Penrose Limits’
Abstract: At high frequencies, the physics near a black hole’s lightring can be captured by Penrose-limit plane waves adapted to the photon sphere. In this talk, I will solve exactly the equations for gravitational perturbations in this limit using Penrose’s 2-spinor formalism, and I will show that the resulting solutions correspond to quasinormal modes (QNMs) in the eikonal regime. I will then prove that gravitational electric–magnetic duality holds on-shell for perturbations at the lightring. This symmetry has long been understood to hold on-shell only for perturbations about flat spacetime. The lightring therefore provides a distinct setting in which it reemerges. In addition, QNM isospectrality follows as an immediate consequence. I will next extend the analysis to nonlinear gravitational fluctuations, where the duality is broken, and compute the excitation of quadratic QNMs, which are particularly relevant given recent prospects for their detection. I will conclude by discussing further directions in which Penrose limits can be used to sharpen our understanding of lightring physics.
