Bologna-Firenze-Pisa meetings in theoretical physics I

Friday 15 Mar 2024, 08:00 → 18:00 Europe/Rome

Aula Altana (Palazzo Strozzi)

Augusto Sagnotti (Scuola Normale Superiore), Claudia Giua (Scuola Normale Superiore), Elisa Guidi (Scuola Normale Superiore), Enrico Trincherini, Guilherme Pimentel (Scuola Normale Superiore)

This event will bring together the theoretical physics groups of Bologna, Firenze and Pisa to discuss recent advances in both high energy theory and phenomenology. Our plan is to have these meetings every two months, with potentially external speakers for future editions.

This edition we'll feature one speaker from each representative institution:

• Gui Pimentel (SNS)
• Michele Redi (UniFI)
• Filippo Sala (UniBO)
• Alessando Vichi (UniPI)

 

The event will be kindly hosted by the school of political sciences of Scuola Normale, based in Palazzo Strozzi, a 10 minute walk from Florence's main station (S.M.N.).

The meeting will take place in "Aula Altana," on the 4th floor, a large room with capacity to host up to 100 participants.

1 Alessandro Vichi: Bootstrapping Mesons at Large N

This seminar explores the bootstrap formalism to study scatting amplitudes in weakly coupled EFTs, leveraging dispersion relations to establish sum rules linking low-energy scattering amplitudes to high-energy partial wave expansion. We analyze the impact of different Regge behaviors at large energies and apply the formalism to study Pion Scattering at large-N.

Imposing the presence of spin-2 states, we derive a mass bound for additional higher spin states, unveiling a kink structure. Investigation at this kink reveals intriguing agreements with real-world QCD observables. Moreover, the solution's spectrum organizes into Regge-trajectory-like families

vichi.pdf

2 Filippo Sala: Hunting for sub-GeV dark matter with its high-energy fluxes

When Sub-GeV dark matter (DM) scatters off nuclei it makes them recoil too faintly to be seen by leading detectors. The community addressed this challenge mainly by proposing novel detection technologies: most of them are still in the conception phase, a few became experiments but are not yet testing motivated DM models. However, relativistic fluxes of light DM necessarily reach us on Earth, and open completely new possibilities to search for DM today, in existing experiments. I will review our proposal to observe sub-GeV DM upscattered by cosmic rays at large neutrino detectors like Super- and Hyper-Kamiokande, JUNO and DUNE. I will then present new strong constraints and sensitivities, from the same experiments, that rely on the high-energy flux of DM produced in atmospheric showers. I will finally discuss how analogous ideas allow to obtain novel knowledge about the relic neutrino background, using data from (ultra-)high-energy neutrino experiments.

BoFiPi_Mar2024_FSala.pdf

3 Gui Pimentel: Kinematic flow and the emergence of time

Motivated by precision calculations of primordial non-Gaussianity, a bootstrap approach for cosmological correlations has been developed over the past few years. A central element in this approach is to determine static differential equations in terms of boundary momenta (at the reheating surface), instead of performing time-evolution integrals. While investigating a toy model of cosmology to better understand these differential equations, we found an autonomous structure, from which time evolution seems to be an output. I will describe the rules of this "kinematic flow," and mention some current investigations being pursued at SNS.

Differential Equations for Cosmological Correlators 2.pdf

4 Michele Redi: The meso-inflationary axion scenario

After reviewing the axion solution of the strong CP problem and its predictions for dark matter, I will describe a new scenario where the axion Peccei-Quinn symmetry is broken after the beginning of inflation. This interpolates between the popular pre-inflationary and post-inflationary axion scenarios with novel phenomenological features. In particular in some regions of parameters space the PQ symmetry breaking is visible after QCD confinement, modifying the predictions for axion dark matter. I will then show, using the stochastic formalism of inflation, that the meso-inflationary axion is realized even in the simplest axion model, the KSVZ axion, when the decay constant of the axion is comparable to the Hubble scale during inflation. Based on https://inspirehep.net/literature/2181203 and https://inspirehep.net/literature/2723225.

Redi_Strozzi 24.pdf