Particle Physics in the Early Universe

14 sept. 2026, 09:00 → 18 sept. 2026, 20:00 Europe/Paris

The International conference “Particle Physics in the Early Universe” is  taking place 14–18 September 2026 in Paris and Orsay.

The conference is co-organized by the Polish Academy of Sciences Scientific Center in Paris, the Institute for Advanced Studies of the University of Warsaw, and IJCLab Orsay. The first day of the conference (Sep 14) will take place in the auditorium Joliot Curie, building 100 at  IJCLab in Orsay.  The sessions of September 15-18 will be held at the Polish Academy of Sciences Scientific Center, located in the elegant 16th arrondissement of Paris. 

The scientific program will explore the interplay between elementary particle physics and early-Universe cosmology, covering topics such as cosmological inflation, dark matter, dark energy, baryogenesis and leptogenesis, phase transitions in the early Universe, and their potential observational signatures, particularly gravitational waves. A central focus will be the cosmological implications of theories beyond the Standard Model and their possible experimental tests. Contributions will be published in a special issue of Acta Physica Polonica B. There is  no conference fee for invited participants.

Confirmed speakers include: 

Zurab Berezhiani
Nicolas Bernal
Matteo Braglia
Chiara Caprini
Thomas Colas
Joe Conlon
Ed Copeland
Marco Drewes 
Emilian Dudas
Ruth Durrer
Joulien Froustey
Yann Gouttenoire
Alejandro Ibarra
Ayuki Kamada
Steve King
Will Kinney
Rocky Kolb
Kamila Kowalska
Fotis Koutroulis
Oleg Lebedev
Marek Lewicki
Marta Losada
Matthew McCullough
Kyohei Mukaida
Marek Olechowski
Marco Peloso
Lucas Pinol 
Sébastien Renaux-Petel
Kazuki Sakurai
Mikhail Shaposhnikov
Pedro Schwaller
Pasquale Serpico
Enrico Sessolo
Joe Silk
Juri Smirnov
David Stefanyszyn
Bogumiła Świeżewska 
Xi Tong
David Wands

The Organizing Committee:
Adam Falkowski (IJClab Orsay)
Zygmunt Lalak (University of Warsaw)
Yann Mambrini (IJClab Orsay)
Stefan Pokorski (University of Warsaw and Polish Academy of Science)

 

lun. 14 septembre

09:00 → 10:00 Registration and Coffee

10:00 → 11:30 Monday

10:00 TBA

Orateur: Ed Copeland

10:45 Dark Matter from a Slightly Broken Mirror

Orateur: Juri Smirnov (University of Liverpool)

11:30 → 12:00 Coffee break

12:00 → 12:45 Monday

12:00 Developments in gravitational particle production

Orateur: Oleg Lebedev (University of Helsinki)

12:45 → 14:00 Lunch break

14:00 → 15:30 Monday

14:00 Nonthermal leptogenesis via cosmological gravitational particle production

Orateur: Rocky Kolb (The University of Chicago)

14:45 Geodesic Completeness in General Cosmological Scenarios

The well-known Borde-Guth-Vilenkin Theorem shows that inflationary
spacetimes are generically geodesically past-incomplete, necessitating
the existence of a pre-inflationary boundary of some sort, possibly
singular. In this talk, I discuss the generalization of the BGV theorem
to spactimes beyond inflation, including inhomogeneous and cyclic
models. I argue that the cyclic model proposed by Ijjas and Steinhardt
is geodesically incomplete, and that an asymptotically de Sitter
version of Penrose's Conformal Cyclic Cosmology is either past- or
future-incomplete.

Orateur: William Kinney (Univ. at Buffalo, SUNY)

15:30 → 16:00 Coffee Break

16:00 → 17:30 Monday

16:00 Non-compact QCD axion and its gravitational origin

Orateur: Prof. Mikhail Shaposhnikov (EPFL)

16:45 Primordial lepton asymmetries: constraints and consequences

Orateur: Julien Froustey (IFIC, CSIC-UV)

17:30 → 19:00 Free discussions

19:00 → 22:00 Dinner at "Le Gramophone" in Orsay

27 Bd Dubreuil, 91400 Orsay

mar. 15 septembre

10:00 → 11:00 Tuesday

10:00 Kowalska

10:30 Lewicki

11:00 → 11:30 Coffee Break

11:30 → 12:30 Tuesday

11:30 Conlon

12:00 TBA

12:30 → 14:00 Lunch Break

14:00 → 15:30 Tuesday

14:00 Berezhiani

14:30 Gravitational Waves from Primordial Black Hole Reheating

I will present the 13 channels of gravitational wave production which are at play when the universe is reheated from the evaporation of a population of primordial black holes dominating the energy density of the universe

Orateur: Yann GOUTTENOIRE (IAP)

15:00 Coupled Dark Energy and Dark Matter for DESI: An Effective Guide to the Phantom Divide

Orateur: Stephen King

15:30 → 16:00 Coffee Break

16:00 → 17:00 Tuesday

16:00 Mukaida

16:30 Sessolo

17:00 → 19:00 Free Discussions

mer. 16 septembre

10:00 → 11:00 Wednesday

10:00 TBA

Orateur: Matteo Braglia (CERN)

10:30 Axion inflation with gauge fields: backreaction and signatures

Orateur: Marco Peloso (University of Padua and INFN, Sezione di Padova)

11:00 → 11:30 Coffee Break

11:30 → 12:30 Wednesday

11:30 Dudas

12:00 McCullough

12:30 → 14:00 Lunch Break

14:00 → 15:30 Wednesday

14:00 Constraining Dissipative Inflation with Open Effective Field Theories

Orateur: Thomas Colas (DAMTP - University of Cambridge)

14:30 Primordial black hole formation from self-resonant preheating in single-field inflation?

Orateur: Pasquale SERPICO (LAPTh)

15:00 Stefanyszyn

15:30 → 16:00 Coffee Break

16:00 → 17:00 Wednesday

16:00 Świeżewska

16:30 New probes of supercool phase transitions and domain walls at PTA frequencies

Orateur: Pedro Schwaller (Mainz University)

17:00 → 19:00 Free Discussions

19:00 → 20:30 Cocktail in the Polish Embassy (TBC)

jeu. 17 septembre

10:00 → 11:00 Thursday

10:00 TBA

Orateur: Marco Drewes (UCLouvain)

10:30 Gravitational production of Sterile Neutrinos

Orateur: Fotis Koutroulis (IHEP, Beijing)

11:00 → 11:30 Coffee Break

11:30 → 12:30 Thursday

11:30 Durrer

12:00 TBA

Orateur: Chiara Caprini (CERN and University of Geneva)

12:30 → 14:00 Lunch break

14:00 → 15:30 Thursday

14:00 A Laplace-space approach to cosmological correlators

Orateur: Sébastien RENAUX-PETEL (IAP - CNRS)

14:30 Modelling Ultra-Slow-Roll Inflation

Orateur: David Wands (University of Portsmouth)

15:00 Pinol

15:30 → 16:00 Coffee Break

16:00 → 17:30 Thursday

16:00 Seesaw cosmology

Orateur: Nicolás Bernal (New York University Abu Dhabi)

16:30 Self-interacting dark matter: non-perturbative dynamics

Orateur: Ayuki Kamada (University of Warsaw)

17:00 TBA

Orateur: Alejandro Ibarra (Technical University of Munich)

17:30 → 19:00 Free Discussions

19:00 → 22:00 Conference dinner in "Piccolino Parigi"

16 Rue Copernic, 75116 Paris

ven. 18 septembre

09:30 → 11:00 Friday

09:30 Losada

10:00 Testing α-attractor models of inflation by CMB and reheating temperature

Orateur: Marek Olechowski (University of Warsaw)

10:30 Sakurai

11:00 → 11:30 Coffee Break

11:30 → 13:00 Friday

11:30 Unveiling the Dark Ages

Orateur: JOE Silk (IAP/JHU)

12:00 Tong

12:30 Ballesteros

13:00 → 14:00 Lunch and Farewell