LIO International Conference 2025 on "New Approaches to Naturalness"

May 20, 2025, 1:30 PM → May 23, 2025, 6:00 PM Europe/Paris

Dirac/RdC-Amphithéâtre (IP2I)

Aldo Deandrea (IP2I - Université Lyon 1), Florian NORTIER (chair) (CNRS/IN2P3 - IP2I Lyon), Nazila Mahmoudi (Lyon University), Luc Darmé (IP2I - Université Lyon 1)

The aim of this workshop is to bring together theorists working on emerging ideas to tackle naturalness issues in theories of the fundamental interactions. Various approaches will be discussed and confronted. The program includes the historical topics related to naturalness:

• Electroweak Hierarchy,
• Flavor Puzzle,
• Strong CP Problem,
• Dark Energy & Inflation.

 

Participation in the conference (max 50 participants) and talks are only on invitation. There is no registration fee.

Important Notice: Conference Housing Information

The conference is not affiliated with any third-party agencies offering housing or accommodation services. We strongly advise participants to ignore any e-mail from third parties claiming to represent the conference.

Tue, May 20

1:30 PM Registration

1:55 PM Welcome Words

Gravity, Forms & Generalized Symmetries

1 TBA

Speaker: Gia Dvali

2 TBA

Speaker: Otari Sakhelashvili

3 TBA

Speaker: Seth Koren

4:00 PM Coffee Break

Cosmological Selection of Vacuum: Part 1

4 TBA

Speaker: Raffaele DAgnolo

5 TBA

Speaker: Pablo Sesma (IPhT Saclay)

6 Revisiting the relaxion

In this talk, I re-visit the original relaxion model by Graham-Kaplan-Rajendran in the regime where the relaxion is subject to large fluctuations during its dynamics. I discuss the modified stopping conditions for such dynamics of the relaxion and the new parameter space. Interestingly, in a significant region of the parameter space, the relaxion can naturally account for the observed dark matter density in the universe.

Speaker: Geraldine Servant (CERN)

Wed, May 21

Cosmological Selection of Vacuum: Part 2

7 TBA

Speaker: Thomas Steingasser

8 A Multiverse Outside of the Swampland

Speaker: Gabriele Rigo (IPhT, Saclay)

10:00 AM Coffee Break

Cosmological Selection of Vacuum: Part 3

9 TBA

Speaker: Maximilian Detering (King's College London)

10 TBA

Speaker: Manuel Ettengruber

Wild Card

11 The Hierarchy Problem Redux

After discussing some history of the hierarchy problem, I recast the hierarchy problem as a legitimate paradox. The premises and reasoning of the paradox are explained. I discuss how each premise has been attacked and what ideas are still standing and which directions are perhaps less interesting today after a generation of experimental and theoretical work.

Speaker: James Wells (University of Michigan)

12:25 PM Lunch Break

Flavor Puzzle: Part 1

12 TBA

Speaker: Dr Giacomo Cacciapaglia (LPTHE)

13 Modular symmetries for flavour physics

Speaker: Stephen F. King

3:50 PM Group Picture

4:00 PM Coffee Break

Flavor Puzzle: Part 2

14 Flavour Deconstruction

Speaker: Prof. Gino Isidori (University of Zurich)

5:25 PM Free Time/Discussions

7:00 PM Conference Dinner

Thu, May 22

Fixed Point & Compositeness: Part 1

15 Phase Structure of Chiral Gauge Theories

We study the IR fate of Chiral Gauge Theories through functional methods and the Effective Average Action. Our results show a rich structure, from the existence of IR conformality to new patterns of Chiral Symmetry Breaking.

Speaker: Shahram Vatani (CP3 UCLouvain)

16 TBA

Speaker: Juan Pablo Garcés Varas

10:00 AM Coffee Break

Fixed Point & Compositeness: Part 2

17 Holographic analysis of near-conformal dynamics and light dilaton

We carry out a detailed analysis of the region slightly outside the conformal window of a non-trivial infrared fixed point in a generic bottom-up holographic setup. We focus on models, which study the dynamics of a scalar field, dual to quark degrees of freedom, in a (nearly) AdS geometry. Such models realize the picture expected for vector-like near-conformal theories from Dyson-Schwinger analysis. The analysis covers a toy model, which allows for analytic solutions, and a more general setup as well, which encompass a complete model for the ultraviolet physics. We analyze the conditions for the appearance of a parametrically light scalar state in the spectrum, which can act as a candidate for the Pseudo-Nambu-Goldstone boson arising from breaking of the approximate conformal symmetry. We also present detailed results for the vacuum structure, correlators, and Ward identities in the near-conformal regime.

Based on: https://arxiv.org/abs/2504.18623

Speaker: Deog Ki Hong

18 TBA

Speaker: Maya Hager

19 Composite Hybrid Inflation

I will describe a model of hybrid inflation coming from a general composite theory. Starting from an effective chiral Lagrangian with a dilaton and pions, we identify inflation occurring during the walking dynamics of the theory. A Z2 symmetry-breaking term in the pion sector induces a shift in the inflaton’s trajectory, which leads to a tachyonic instability phase. Curvature perturbations grow exponentially, producing copious primordial black holes and a stochastic gravitational wave background. We show that the primordial black hole mass and the gravitational wave frequency is strongly restricted by the anomalous dimension values, with larger anomalous dimensions giving lighter primordial black holes, and higher frequency gravitational waves. Future gravitational wave observatories are within the reach of probing associated signatures.

Speaker: Wanda Isnard (IP2I Lyon)

12:25 PM Lunch Break

Fixed Point & Compositeness: Part 3

20 TBA

Speaker: Kamila Kowalska

21 TBA

Speaker: Andreas Trautner (Max-Planck-Institut fuer Kernphysik Heidelberg)

3:25 PM Coffee Break

ALPs, pNGBs & Accidents: Part 1

22 TBA

Speaker: Emilian Dudas (Ecole Polytechnique)

23 Exploring the Boundaries of Naturalness

Speaker: Matthew McCullough (CERN)

5:45 PM Free Time/Discussions

Fri, May 23

ALPs, pNGBs & Accidents: Part 2

24 TBA

Speaker: Enrico Nardi (INFN Roma Italy & Universidad de Antioquia, Medellin Colombia)

10:05 AM Coffee Break

ALPs, pNGBs & Accidents: Part 3

25 pNGB Higgs Naturalness at a Tipping Point

For pNGB-based approaches, the phenomenological question of Higgs naturalness finds itself at a tipping point between direct searches and precision. As we look ahead to the HL-LHC era and beyond, a scenario in which all measurements remain Standard Model-like would only sharpen the naturalness tension, driven increasingly by precision constraints. To illustrate this from a fresh perspective, we construct a maximally natural model, throwing into the mix three approaches to symmetry-based naturalness: Supersymmetry, Twin Higgs, and Gegenbauer-like pNGB Higgs models. We use the 'Kitchen Sink' model to discuss the interplay between direct exploration and precision, and the implications for FCC-ee and FCC-hh.

Speaker: Adriana Guerrero Menkara

26 TBA

Speaker: Felix Bruemmer (LUPM Montpellier)

12:00 PM Lunch Break

UV/IR Mixing

27 TBA

Speaker: Irene Valenzuela (IFT UAM-CSIC Madrid)

28 TBA

Speaker: Steven Abel (IPPP)

3:20 PM Last Words

3:30 PM Coffee Break

4:00 PM Free Time/Discussions