Figure caption: The rules governing the dynamics of the balls in the "box ball system" can be illustrated with the help of a carrier that loads and unloads the balls by running through the system from left to right at each time step.   Understanding how macroscopic laws and large-scale properties emerge from the microscopic interactions between the constituents of a system is a major problem in statistical physics. One can for instance consider the appearance of hydrodynamic behaviors or the way currents react to external forces. It is generally very challenging to connect the microscopic rules to these large-scale properties, and there are relatively few systems for which exact results can be obtained. The “Box-ball system” (BBS), a particular cellular automaton, is such an example. The BBS consists of “balls” occupying “boxes” arranged on a line, with at most one ball per box.

Many natural systems remain far from thermodynamic equilibrium by exchanging matter, energy or information with their surroundings. As these transfers, or fluxes, break timereversal invariance, such processes are beyond the realm of traditional thermodynamics and their statistical fluctuations do not follow the principles of equilibrium statistical mechanics. Though a fully general theory of non-equilibrium systems still remains to be constructed, a physical principle describing the macroscopic behaviour of diffusive systems far from equilibrium has been proposed by G. Jona-Lasinio and his collaborators in 2001: this is the Macroscopic Fluctuation Theory (MFT). In the MFT framework, macroscopic fluctuations far from equilibrium are determined by two coupled non-linear hydrodynamic equations. However, for a long time, the MFT equations have remained intractable. In a recent work that has appeared in Physical Review Letters, K. Mallick (IPhT), H. Moriya and T.

The IPhT is strongly involved in the preparation of the scientific exploitation of the Euclid mission. This participation is done at two levels. Francis Bernardeau is in charge of the coordination of the Science Performance Verification, an exercise that aims to ensure that the core objectives of the mission - constraints on the parameters of the dark energy equation of state - will be achieved given what is known about the general parameters of the mission. But more generally, the IPhT researchers are involved in the preparation of the tools necessary for the analysis of cosmological data. In particular, it is a question of developing and validating the tools allowing to predict the expected observables for a large variety of cosmological models. Thus, Filippo Vernizzi coordinates the efforts within the Euclid consortium to develop simulations and theoretical tools to study the non-linear development of modified gravity models.

Conference: June 6-10 - Workshop: June 13-17

Very light scalar fields could be at the origin of large-scale phenomena such as dark energy. Unfortunately, they would also lead to large deviations in solar system physics. For instance, they would appear as fifth forces and deviate planets in their orbits around the Sun. This can be avoided if their local effects are screened. Screening mechanisms are now well understood and currently tested in the laboratory. Associated light scalar particles could also be created from photons in dense environments in the presence of intense magnetic fields. This could happen deep inside the Sun where magnetic fields can reach several Tesla. These light particles would then propagate through the interplanetary medium and penetrate the earth’s atmosphere. Detectors such as XENON1T, originally designed to detect the presence of dark matter, can be used to track the passage of these elusive light particles. In 2020, the XENON1T experiment claimed to have seen an unexpected signal.

Mariana Graña and Stéphane Lavignac, researchers at the IPhT, are among the organizers of the 2022 session of the Planck Conference Series « From the Planck scale to the electroweak scale ». The conference will be held in Paris from May 30 to June 2nd, complemented on June 3rd by a special day dedicated to Ignatios Antoniadis, one of the founders of these conferences.

We warmly welcome Luc Blanchet, who will be a regular visitor of the IPhT  during the next six month. 

The Institut de Physique Théorique invites applications for a junior CEA permanent position in quantum condensed matter theory or/and quantum information sciences. Candidates with interest in one of the following scientific areas will be considered with the highest priority: Quantum matter, quantum and topological materials, classical and quantum simulations, quantum computing, quantum communication Interested candidates should apply via AcademicJobsOnline (Job #20967) and applications should be received by March 1st, 2022 in order to receive full consideration. Contact: position2022@ipht.fr  

The Institut de Physique Théorique invites applications for a junior CEA permanent position in theoretical physics. Candidates with interest in one of the two following scientific areas will be considered with the highest priority: « High-energy phenomena and quantum field theory, from amplitudes and integrability to gravitational waves » « Applications of statistical physics: physics of life, artificial intelligence, neuroscience, complex systems, etc.». Interested candidates should apply via AcademicJobsOnline (Job #20703) and applications should be received by Feb. 15, 2022 in order to receive full consideration. Contact: position2022@ipht.fr