Seminar: “The Search for New Physics in Accelerators and the Cosmos” SPRING 2026

This talk proposes a direct link between the hierarchy problem and Weakly Interacting Massive Particles (WIMPs): we suggest that the small mass of the Higgs boson arises from being dynamically driven to the scale of the WIMP. Such a special electroweak vacuum is singled out by lying close to the critical boundary of a phase transition, as recently explored in a new class of cosmological solutions to the hierarchy problem. They generically predict the Higgs potential to be destabilised just above the weak scale. Intriguingly, the requirement for new physics to achieve this coincides with two independently well-motivated expectations: a split spectrum of light fermions and heavy bosons, as anticipated from naturalness, and the so-called "WIMP miracle". A WIMP with mass around the weak scale not only happens to have the correct thermal relic abundance to be the dark matter (DM), it can also give rise to the necessary critical boundary at the TeV scale through its Yukawa couplings to the Higgs. We use a higgsino-like singlet-doublet model to illustrate our Higgs-DM criticality scenario and show that if this WIMP DM mass is observed to be greater than ~1.2 TeV then it necessarily implies a strong bound on the Higgs mass and an upper bound on the scale of heavy new physics that restores vacuum stability. It can be thoroughly probed in direct detection experiments, astrophysical signals and future collider searches, further motivating a comprehensive exploration of the remaining heavy WIMP parameter space.

I will talk about dispersion relations (analog of Kramers-Kronig relations) for tidal Love number of weakly gravitating compact objects.

The holographic principle suggests that quantum gravity can be described by an equivalent lower-dimensional field theory. While this idea is well-established in anti–de Sitter space, extending it to more realistic settings remains an open challenge. This talk presents recent progress toward a flat space hologram, where scattering amplitudes are expressed as correlators at null infinity. I will discuss how asymptotic symmetries guide a new framework linking infrared physics, quantum information, and the organization of scattering data, and outline key questions still to be resolved.

Las teorías finitas de gran unificación son teorías del campo supersimétricas que están libres de divergencias en el UV, esta libertad se codifica en función de sus RGE's, exhibiendo del mismo modo una invarianza ante transformaciones conformes. En este trabajo se estudia el rompimiento de supersimetría en este tipo de modelos desde dos puntos de vista; el primero es un estudio teórico del efecto de la reducción de acoplamientos en el sector de rompimiento suave y su relación con el mecanismo de rompimiento mediado por efectos de la anomalía conforme. El segundo punto es un estudio de la fenomenología del rompimiento por medio del mecanismo de split-SUSY, analizando el efecto de la finitud en la teoría sobre los valores de los quarks pesados del modelo estándar y el escalar de Higgs, así como las perspectivas a dar un candidato viable a materia oscura.

Feynman integrals are ubiquitous in any calculation in perturbative quantum field theory. Their calculation is a crucial ingredient in computing loop amplitudes, which allow us to increase the precision of theoretical predictions for physical processes ranging from collider experiments to gravitational waves measurements. I will give an overview of some modern techniques used in the calculation of Feynman integrals, focusing on cases with many external legs. I will explain how Feynman integrals form vector spaces, and how this can be used to simplify their calculation by targeting a basis of this space. Finally, I will show how a better understanding of the analytic structure of the functions appearing in the evaluation of Feynman integrals can lead to more efficient ways to compute them.

The direct detection of gravitational waves has put the relativistic
two-body problem in the spotlight and stimulated progress in
perturbative approaches that provide analytic insight into its dynamics. Two strategies that have been witnessing interesting developments to this end are the ones based on scattering amplitudes, which apply to binary scatterings at large impact parameter, and on black-hole perturbation theory, which applies to extreme-mass-ratio binaries. In this talk, I will discuss how these two methods play complementary roles, and how they can be employed to calculate the gravitational perturbations induced by scatterings of black holes both at null infinity and close to the event horizons.

QCD remains intractable in the high-energy soft regime, where all standard methods break down. This regime governs total hadronic cross-sections, which have long been observed to grow with energy, a phenomenon that is still very poorly understood today. In this talk, I will argue that the modern S-matrix bootstrap provides a systematic way to tackle this regime of QCD. I will derive an upper bound on the total cross-section at finite energy and present the strongest interacting amplitude that the bootstrap outputs. I will compare these results with proton–proton experimental data.

En este trabajo, exploramos una variante del mecanismo seesaw donde las masas de los neutrinos ligeros se generan mediante correcciones radiativas (a un loop). En este marco, calculamos cómo los neutrinos de Majorana virtuales contribuyen al vértice $WWh$. De este cálculo surgen varios acoplamientos anómalos, tanto $CP$-pares como $CP$-impares.Hicimos estimaciones numéricas analizando el rol de este vértice en dos escenarios: la producción $Wh$ en colisiones protón-protón y la fusión de bosones vectoriales en un colisionador de leptones. Nuestros resultados indican que, por ahora, estos acoplamientos están fuera del alcance experimental actual. Sin embargo, los acoplamientos que conservan $CP$ podrían alcanzar valores de $\sim 10^{-3}$, lo que los pondría casi al alcance de la fase de Alta Luminosidad del LHC. Por otro lado, los efectos de violación de $CP$ andan por el orden de $\sim 10^{-4}$, que todavía queda bastante lejos de lo que se espera medir en el CLIC (Compact Linear Collider).

It is demonstrated that non-extensive entropies depending solely on probability (Obregón, 2010) yield generalized propagators, consequently modifying the wave function. Furthermore, our recent work explores how these entropies impact General Relativity; specifically, by employing Jacobson and Wald formalisms, we have derived an f(R) Lagrangian consistent with these frameworks.