Presentation of IPhT : The Institute of Theoretical Physics (IPhT) is an Institute of the Direction of Fundamental Research (DRF) of the Commissariat for Atomic Energy and Alternative Energies (CEA).

Next Carlo Heissenberg's arrival at IPhT!

Carlo Heissenberg graduated with flying colors in 2019 from the Scuola Normale Superiore di Pisa, the Italian twin sister of the Ecole Normale de Paris. His initial research focused on the infrared properties of gravitational theories and higher spin theories from the perspective of asymptotic symmetries, a topic that later found phenomenological applications in the context of gravitational wave studies.

It was during his first postdoctoral period at Nordita-Uppsala (2019-2023) that Carlo started working on gravitational wave physics using ideas borrowed from particle physics, such as scattering amplitudes and eikonal exponentiation in particular. He quickly became a leader in the field, publishing several important papers with world-famous physicists such as Gabriele Veneziano. Carlo's group achieved, for instance, the first complete calculation of the gravitational deflection angle to the third post-Minkowskian order in the Newton coupling constant expansion, while simultaneously resolving the high-energy limit problem that was puzzling the community.

In the meantime, Carlo was granted a Marie-Curie fellowship and moved to his second postdoc at Queen Mary, while continuing to work on gravitational wave physics, focusing on new observables (waveforms, angular momentum loss, effect of spins…) that could be calculated efficiently using scattering amplitudes techniques.

**Carlo accepted an offer from the IPhT and will join the lab as a permanent member in Fall 2024.**

E. De-laborderie, 2024-03-15 10:17:00

Measuring the speed of sound at 2.5 trillion degrees

Collisions between nuclei of lead atoms are carried out at the Large Hadron Collider (LHC) at CERN to study the quark-gluon plasma, a state of matter where neutrons and protons are dissociated into their elementary constituents, quarks and gluons. Its temperature at the LHC has been measured to be (2.540+-0.090) trillion Kelvin [1], [3]. Another important thermodynamic property is the compressibility, which is related to the speed of sound through standard thermodynamic identities.

Back in 2019, Fernando Gardim (a physicist from Brazil who was on sabbatical leave at IPhT), Giuliano Giacalone (PhD student at IPhT) and Jean-Yves Ollitrault (IPhT) proposed to extract the speed of sound from LHC data by analyzing "ultracentral" collisions, defined as collisions at zero impact parameter [2]. The number of particles in ultracentral collisions can vary by 10-15%, corresponding to a variation of density, which can be used to probe the compressibility. They predicted that the momentum per particle, which is proportional to the temperature, should increase as a function of the multiplicity, and that the relative change would provide a direct measure of the speed of sound.

This prediction [2] has motivated a dedicated analysis by the CMS collaboration at the LHC [3]. CMS has recently observed the predicted increase of the momentum per particle and extracted a precise measure of the speed of sound, (49.1 +- 1.6)% of the speed of light, in perfect agreement with first-principles calculations from the theory of strong interactions, QCD.

[1] *"Thermodynamics of hot strong-interaction matter from ultrarelativistic nuclear collisions"*, Fernando G. Gardim, Giuliano Giacalone, Matthew Luzum, and Jean-Yves Ollitrault. Nature Physics Letters 16 (2020) 615-619, https://doi.org/10.1038/s41567-020-0846-4

Voir aussi : https://www.ipht.fr/Phocea/Vie_des_labos/News/index.php?id_news=1032

[2] *"Measuring the speed of sound of the quark-gluon plasma in ultracentral nucleus-nucleus collisions"*, Fernando G. Gardim, Giuliano Giacalone, Jean-Yves Ollitrault https://arxiv.org/abs/1909.11609v1. Physics Letters B 809 (2020) 135749 https://doi.org/10.1016/j.physletb.2020.135749

[3] *"Extracting the speed of sound in the strongly interacting matter created in ultrarelativistic lead-lead collisions at the LHC"*, CMS Collaboration, https://arxiv.org/abs/2401.06896. Submitted to Reports on Progress in Physics.

R. Guida, 2024-03-05 16:17:00

Two IPhT researchers feature in the latest issue of "Sciences et Avenir- La recherche".

Two IPhT researchers feature in the latest issue of "Sciences et Avenir- La recherche" (925, March 2024).

Kirone Mallick was interviewed as part of the article "Maison Poincaré - Les mathématiques en partage" marking the opening of the new Maison Poincaré at the Institut Henri Poincaré. Clémentine Laurens interviewed Kirone, a mathematician, and a biologist. Among other topics, Kirone explains the relationship between physics and mathematics.

Francis Bernardeau, Deputy Director of the Euclid consortium, was interviewed as an expert cosmologist for a special report on Dark Energy (by Fabrice Nicot and Sylvie Rouat) in the same journal issue. In his intervention, Francis gives the general public an overview of the various theoretical models that describe the nature of dark energy, which accounts for around 68% of the energy in the known universe.

R. Guida, 2024-02-29 19:06:00

LISA mission gets the go-ahead from ESA

2024-01-26 16:35:00

2024-01-17 15:58:00

A Marc Barthélémy and Vincent Verbavatz's new book: Statistics of Urban populations.

2024-01-11 16:21:00

One IPhT scientist involved in the top 10 breakthroughs of 2023!

2024-01-10 10:55:00

Welcome to Anne Capdepon, Deputy Head of Research Support at the IPhT.

2023-12-14 09:54:00

The first images taken by Euclid revealed

2023-11-17 16:21:00

Celebration of IPHT's 60 years birthday

2023-11-17 15:42:00

A Starting ERC Grant for Ben Wieder

2023-09-06 15:32:00

Death of Michel Gaudin (02/12/1931 -- 04/08/2023)

2023-08-24 09:49:00

2023-07-18 20:42:00

Efficient algorithms for scattering amplitudes

2023-07-12 15:18:00

Matt Von Hippel is to join IPhT on September 1.

2023-05-30 09:40:00

Antoine Bourget joins the IPhT as a permanent researcher!

2023-05-02 14:25:00

The Benchmark for Quantum Computer Performance (BACQ)

2023-05-02 11:42:00

Nomination of Henri Orland to the American Academy of Arts and Sciences

2023-05-02 11:17:00

Calculating the Witten-Kontsevich intersection numbers

2023-04-11 10:29:00

Monica Guica receives the CNRS bronze medal for the year 2023!

2023-04-03 15:21:00

27th Itzykson Conference : Fluctuations far from Equilibrium

2023-03-21 15:39:00

2023 Galileo Galilei Medal for David Kosower (IPhT), Zvi Bern(California U) and Lance Dixon (SLAC)

2023-02-17 09:04:00

Quantum networks : Entangled ions across the university campus Innsbruck

2023-02-10 15:11:00

Hamiltonian paths, a challenge for KPZ.

2023-02-03 15:19:00

Kibble-Zurek phenomenon: from the early Universe to a spin chain

2023-02-03 14:15:00

Kirone Mallick winner of the 2022 Physics French Society (SFP) Paul Langevin Prize

2023-02-01 15:18:00

EPS PhD prize awarded to IPhT student

2022-11-04 10:33:00

Exact Macroscopic Fluctuations Far from Equilibrium

2022-08-25 15:09:00

Preparation of the exploitation of the Euclid mission

2022-07-11 16:06:00

Retreat of the IPhT in Autrans : aftermath

2022-06-22 09:05:00

Arrival of Ben Wieder on next september

2022-06-17 15:12:00

Arrival of Dalimil Mazáč at IPhT

2022-06-07 10:14:00

Maps day at IPhT on 24 June 2022

2022-06-03 10:33:00

Quantum bounds and fluctuation-dissipation relations

2022-05-12 11:47:00

26ème conférence Itzykson : "Black-Hole Microstructure IV"

2022-05-12 10:32:00

Colloquium Rencontres de l'IPhT in Autrans (Vercors) from 23 to 25 May.

2022-05-12 10:02:00

An extension of Tutte's formula 60 years later

2022-04-20 11:13:00

2022-04-05 11:28:00

Public talk of Stephane Lavignac on Tuesday March 15th

2022-03-11 09:17:00

A new book written by Marc Barthélémy about spatial networks

2022-02-22 11:05:00

Cédric Villani at IPhT on March 1st

2022-02-22 10:26:00

Summer School in Cargèse around exotic superconductivity

2022-02-07 15:39:00

Langevin Prize of the French Society of Physics for Mariana Graña

2022-02-04 10:46:00

2022-02-01 09:21:00

Maxime Leroy joins the IPHT support team

2022-01-27 15:24:00

Un lien entre la masse du boson de Higgs et la constante cosmologique

2021-11-25 14:11:00

Conférence exceptionnelle de Cédric Villani le lundi 22 novembre à 19h30 (Institut Pascal)

2021-11-18 14:33:00

Mathematical Harmony and the Quantum World

2021-10-07 15:24:00

The art of mathematical physics

2021-09-01 16:31:00

Correlation functions and wave functions in solvable models

2021-08-31 16:44:00

2021-05-01 11:45:00

Multipole Ratios : A New Window into Black Holes

2020-11-27 15:16:00

Orazio Scarlatella lauréat du prix de thèse Physique des Ondes et de la Matière (PhOM) 2020

2020-11-26 11:07:00

Modeling the city: an equation ends centuries-old controversies

2020-11-19 11:10:00

Quantum entanglement: A single photon takes two optical paths by "entangling" them!

2020-10-15 15:06:00

An strongly secured encryption

2020-09-17 17:01:00

Un nouvel ouvrage co-écrit par Pierfrancesco Urbani, physicien à l’IPhT

2020-01-31 14:15:00

Un nouvel ouvrage co-écrit par Henri Orland, physicien à l'IPhT

2020-01-28 16:16:00

From theoretical physics to artificial intelligence

2016-01-13 00:00:00

Tue, Apr. 23rd, 11:00-12:00

Séminaire général de l'IPhT - Sophie Szopa

Tue, Apr. 23rd, 14:00-15:00

Séminaire de physique des particules et de cosmologie - Lucas Pinol

Tue, Apr. 30th, 14:00-15:00

Séminaire de physique des particules et de cosmologie - Stefan Stelzl