Elementary Particles

High-energy physics is devoted to the study of fundamental interactions between elementary particles. The currently accepted theory of fundamental interactions – the Standard Model (SM) – has proven to be extremely accurate in describing the ultimate constituents of matter that can be measured experimentally. However, there are serious reasons to believe that it cannot represent a complete theory of the laws of nature, and we devote part of our research to the study of different theories going beyond the SM, whose aim is to describe this New Physics (NP).

Table of elementary particles.

Higgs Boson Physics

Contacts: A. DEANDREA, F.N. MAHMOUDI & F. NORTIER

The Higgs field is the origin of the mass of the elementary particles in the SM. The discovery of its main signature, the Higgs boson, has given us new tools to study the physics of spontaneous electroweak symmetry breaking.

Left: “Sombrero” potential of the Higgs field. Right: Feynman diagrams of the Higgs boson production modes at the LHC, and pie chart of the branching ratios (BRs) of its main decay channels.

The team proposed a new parameterization of the Higgs boson couplings, which allows to directly extract the loop contributions of New Physics (NP). We extended our studies by including a second Higgs boson, and we collaborate with CMS for the interpretation of the low-mass results. We are working on the characterization of the supersymmetric and composite Higgs sector, as well as on the prospects for future colliders such as the FCC.

Flavor Physics

Contact: S. DAVIDSON, L. DARMÉ, A. DEANDREA & F.N. MAHMOUDI

Flavor physics is at the heart of many unanswered mysteries in the SM and is intimately linked to the Higgs sector via Yukawa couplings. Therefore, solving the flavor puzzle involves seeking to elucidate the origin(s) of: the replication in generations of fermions, their mass hierarchy, the mass of neutrinos, the particular textures of quark and neutrino mixing matrices, and the matter-antimatter asymmetry via CP violation.

Left: Legend has it that Murray Gell-Mann and his student Harald Fritzsch came up with the idea of ​​distinguishing quarks by their “flavor” and “color” in 1971, while testing different flavors of ice cream. Center and right: Examples of Feynman diagrams, known as “penguin diagrams,” in flavor physics in the SM (center) and in a supersymmetric model (right).

Flavor physics has become an emerging field to probe new phenomena, mainly due to the emergence of several deviations from SM predictions in B-meson semi-leptonic decays. The ANR topic of F.N. MAHMOUDI focus on precision calculations of these observables, and more precisely the calculation of local and non-local hadronic effects. This constitutes an important challenge in the field, and a necessary step to unambiguously distinguish SM hadronic effects from potential NP phenomena. We have recently proposed a new method for calculating local form factors to reduce systematic theoretical uncertainties. We are also working on the theoretical interpretation of these anomalies in an NP context. For this, we will consider effective field theory approaches, with multidimensional fits of observables, as well as specific UV-models (supersymmetric models, extended scalar sector, etc). In parallel, the recruitment of L. DARMÉ opens collaborations on the phenomenology of flavor transfer models, as well as their experimental constraints. The return of S. DAVIDSON allows us to complete our activities by studying the phenomenological constraints on the change of flavor in the leptonic sector, initiating moreover collaborations with nuclear physics theorists. Finally, we are working on the development of numerical codes that will allow studying the phenomenological implications of experimental data. Our goal is in particular to automate the calculation of flavor observables in any NP model. Therefore, the public code SuperIso, for the calculation of flavor physics observables, has been considerably improved in recent years.

Collider Phenomenology

Contacts: L. DARMÉ, A. DEANDREA & F.N. MAHMOUDI

High-energy proton collisions continue to provide new high-precision results in previously unexplored energy regions. These results can be used to test theories beyond the SM.

Simulation of the showers of subatomic particles produced in the CMS detector, during the collision of proton-proton beams at the CERN LHC.

The team has developed world-class expertise in the phenomenology of heavy vectorlike quarks, composite Higgs, supersymmetry, and has developed several numerical tools for the detection of such particles at the LHC. We implemented vectorlike quarks with generic couplings in Monte Carlo tools such as MadGraph, allowing model-independent studies. NLO effects in QCD are also included, and our tools are regularly used by experimental collaborations, such as CMS, for the production of Monte Carlo data. We continue to develop the public code MARTY, which aims to perform automatic calculations of amplitudes, cross sections and Wilson coefficients in any NP model. The team is involved in the scientific preparation of future colliders, including the electron-positron and proton-proton FCCs, and is eagerly awaiting the start-up of the HL-LHC.

Extensions of the Standard Model

Contacts: L. DARMÉ, A. DEANDREA, F.N. MAHMOUDI, F. NORTIER & D. TSIMPIS

Beyond the flavor puzzle, there are several motivations to build extensions of the SM, such as dark matter, the electroweak hierarchy problem, the strong CP problem, gauge coupling unification, quantum gravity, etc.

Artistic illustration of various physics topics beyond the SM, represented by islands separated by seas of unknowns.

The team has developed expertise in different classes of models: extra dimensions, composite models, supersymmetry, extended scalar sectors, dark matter. The recruitment of F. NORTIER has allowed us to acquire new expertise on models with UV/IR mixing and non-locality. Concerning models with extra dimensions, we have proposed new models for dark matter candidates arising from geometric symmetries. We studied “gauge-Higgs unification” models, and shown the possibility of a unification of gauge and Yukawa couplings. Currently, we are building phenomenological models with compactifications on hyperbolic geometries, such as nilmanifolds and their implications for gauge-Higgs unification scenarios. In parallel, we are developing asymptotic grand unification models, with dark matter candidates called “Indalos”. As for composite Higgs models, we study the phenomenology of new resonances predicted by these models, and we developed UV-completions with fermionic fundamental constituents. In addition, we studied flavor constraints on composite models or with extra dimensions. Finally, we participate in the development of the GAMBIT code, whose goal is to perform global fits for generic NP scenarios.

N.B.: Page under construction. Update required.

Hadrons, Nuclei & Stars

Nuclear and hadronic physics is the study of atomic nuclei and their constituents: quarks and gluons. Some phenomena that we study occur at relatively low energy, while others occur in extreme environments, such as the interior of hot and dense stars.

Nuclear matter: from quarks and gluons to neutron stars.

Contacts

• X. ARTRU
• M. BENDER
• G. CHANFRAY
• K. BENNACEUR
• D. DAVESNE
• M. ERICSON
• H. HANSEN
• J. MEYER
• J.-M. RICHARD

Nuclear Energy Density Function Methods

The activities of nuclear structure physics focus on the description of low-energy phenomena with energy density functions (EDF). In recent years, we have focused on three aspects of these methods: the construction of generalized forms of EDFs and the establishment of advanced fitting protocols for adjusting their parameters; the construction of numerical tools to describe the ground and low-layer states of complex nuclei, and to characterize the effective interaction; and the application of available parameterizations and codes to questions of experimental interest.

There are several motivations, both phenomenological and formal, to study more general forms of the EDF. Several directions are currently being explored. In order to improve the performance of Skyrme-type contact interactions, their generalization including terms with four (N2LO) and six (N3LO) gradients is considered. To overcome some formal problems, a new type of nonlocal EDF based on finite-range generators has been proposed. New formal and numerical developments and exploratory fittings have been carried out.

A second major focus of this activity is the development of tools to study the properties of complex finite nuclei. One of these is a new 3D Cartesian coordinate code for self-consistent mean-field calculations. This code replaces the codes we have developed in the past and offers several major improvements, including numerical accuracy, a significant reduction in computation time, and a reduction in the need for fine tuning of numerical parameters. The second tool that is also constantly maintained and improved is a code for calculations of the generating coordinate method, based on the projected mean-field states of angular momentum and particle number.

Another activity of our group is related to the development of relativistic effective Lagrangians. The first relativistic Hartree-Fock-Bogoliubov calculation at finite temperature was performed by our group and applied to understand the pairing properties in finite nuclei, such as pairing persistence or pairing reentry, predicted in the drip-line nuclei of 48Ni and 48Si. The latter was also predicted to be a closed double-layer and double-bubble nucleus.

Neutrino-Nucleus Interaction & Hadronuclear Physics

One of the recognized expertise of our group concerns the interface between the nuclear many-body problem and the physics of its constituents. Our nuclear model for the neutrino-nucleus interaction incorporates np-nh interactions. This proposal is now recognized as a breakthrough. We compared our results with those of the “Continuum Random Phase Approximation” (CRPA), and we successfully tested our model on MiniBooNE or T2K data.

We have solved another outstanding problem concerning the determination, in a given event, of the true neutrino energy from the information provided by the characteristics of the emitted lepton: its energy and its emission angle. We have introduced the distribution of the real energy around this reconstructed value and shown the existence of a low-energy shift induced by the excitations of the multinucleons.

Another topic concerns the coupling between the strong interaction of the n-body problem and the structure of the nucleons. In a chiral approach including the response of the nucleon to the nuclear vector and to the scalar fields, an EDF has been constructed, with parameters constrained by a non-perturbative QCD and the phenomenology of hadrons.

Hadronic Matter & Quark-Gluon Plasma

One of the recognized expertises of our group concerns the interface between the nuclear n-body problem and the physics of its constituents. Our nuclear model for the neutrino-nucleus interaction, incorporates the np-nh interactions. This proposal is now recognized as a breakthrough. We compared our results with those of the “Continuum Random Phase Approximation” (CRPA), and we successfully tested our model on MiniBooNE or T2K data.

We have solved another outstanding problem concerning the determination, in a given event, of the true neutrino energy from the information provided by the characteristics of the emitted lepton: its energy and its emission angle. We have introduced the distribution of the real energy around this reconstructed value and shown the existence of a low-energy shift induced by the excitations of the multinucleons.

Another topic concerns the coupling between the strong interaction of the n-body problem and the structure of the nucleons. In a chiral approach including the response of the nucleon to the nuclear vector and to the scalar fields, an EDF has been constructed, with parameters constrained by non-perturbative QCD and the phenomenology of hadrons.

Multiquarks

We have analyzed the spectroscopy of string-inspired models, and studied new flavor configurations for tetraquarks, pentaquarks and di-baryons with heavy quarks. We are currently working on heavy quark correlations.

Few-Body Systems

We have shown that some models of hyperon-nucleon and hyperon-hyperon interaction allow the existence of new light hypernuclei with strangeness S=-2. Our recent work includes the first study of an exotic three-body atom, and a review of the Hall-Post inequalities with new developments and applications.

We have realized the first three-dimensional (N,Z,S) hypernuclear diagrams based on a new density functional approach, and have studied the strangeness composition of these hypernuclei.

Neutron-Antineutron Oscillations

The neutron-antineutron oscillations in 40Ar have been revisited, in connection with the members of the DUNE collaboration. The spatial distribution of the antineutron cloud around the 39Ar nucleus and its subsequent annihilation have been estimated and used in the Monte Carlo simulations for the DUNE experiment.

Properties of Compact Stars: Equation of State, Thermal Emissivity, Neutrino Scattering

The inner core of neutron stars can reach high densities where a phase transition to deconfined quarks can occur. We have launched an ambitious research program to confront observations with a large set of nuclear equations of state, by setting up a meta-model for nuclear matter inspired by the EDF approach.

Neutrino scattering in neutron stars is crucially related to the neutrino spectrum observed on Earth. We have analyzed the coherent scattering of neutrinos in non-uniform matter, in order to clarify whether a coherent effect could enhance the scattering, thus reducing the neutrino mean free path.

Quark Polarimetry & Electromagnetism

We develop a recursive model for the Monte Carlo simulation of the fragmentation of a polarized quark, reproducing the Collins effect. A simplified version, where only pseudoscalar mesons are emitted, has been implemented in a Monte Carlo program interfaced with PYTHIA. The simulations are in qualitative agreement with COMPASS and BELLE data. In a stand-alone program, vector mesons have been included. We have found an analogue of the Collins effect in atomic physics.

We have studied the light created in an optical fiber when a charged particle passes through or near the fiber. We have highlighted the common properties of synchrotron radiation and light escaping from a bent optical fiber. We are involved in research on positron sources assisted by channeled radiation.

Current Activities

The development, implementation, fitting and validation of generalized nuclear energy density functions for the study of nuclear structures will be continued, with the long-term goal of extending their application to the mean-field level (and possibly beyond) and improving their predictive power. Particular emphasis will be placed on improving the description of the properties of very heavy and superheavy nuclei, which requires in particular better control of single particle spectra in deformed nuclei. Calculations of charge radii, electromagnetic moments, rotation band characteristics and other observables will be used in the evaluation of future experiments to be performed at ISOLDE/CERN, GANIL and elsewhere.

Our group studies the links between bare nuclear interactions, such as the exchange potential of a Bonn-type boson, and effective relativistic Lagrangians developed for finite nuclei and uniform matter. Our project aims to improve the boson exchange potential and to bridge the gap between the bare nuclear potential and the effective approaches used in finite nuclei. The ultimate goal of our project is to determine whether a new meson exchange Lagrangian, fitted to nucleon-nucleon scattering and complemented by off-shell interaction couplings, could bridge the gap between few-body and n-nucleon systems. Applications of this new model to neutron star crustal physics will also be investigated. This approach can be extended to the strange sector, including hyperon interactions.

We will continue and refine the construction of generalized Nambu-Jona-Lasinio models incorporating simultaneously chiral symmetry breaking and confinement, using either the field correlator method or the Coulomb gauge in QCD. One goal is to improve the calculation of condensates using an RPA-like method, but the main goal will be to derive an effective theory for nuclear physics or neutron star matter, generating at the microscopic scale the nuclear vector and scalar fields, and the medium polarization of nucleons, from pure QCD parameters (string tension and correlation length).

A better characterization of the properties of merging stars can translate into a better knowledge of the equation of state of dense matter, with potential indications for phase transitions, as well as for the conditions of heavy element nucleosynthesis. We plan to implement state-of-the-art microphysics in a global simulation for neutron star mergers, initially provided by D. Radice.

Other ongoing activities include work on luminous hypernuclei to include charmed baryons; systematic study of weak decays of stable tetraquarks, to predict their lifetimes and provide clues for discovery channels; simulation models of polarized quark jets and their polarimetry: search for effective estimators of quark polarization, and simulation of “spin entanglement” of two jets in e+e- annihilation.

N.B.: Page under construction. Update needed.

Astroparticles & Cosmology

Connections with astroparticle physics and cosmology are of great importance for understanding the properties of physics beyond the SM, particularly through its relationship to dark matter and dark energy, which constitute the majority of the current total energy composition of the observable Universe.

Top left: Simulation of the gravitational wave resulting from the merger of two black holes. Top right: Pie chart of the current energy composition of the Universe. Bottom: Schematic view of the expansion of the Universe during its cosmological history.

Contacts

• A. ARBEY
• L. DARMÉ
• S. DAVIDSON
• A. DEANDREA
• F.N. MAHMOUDI
• H. HANSEN
• S. HOHENEGGER
• D. TSIMPIS

Dark Matter

The activities on dark matter focus on the search for new particles by direct or indirect detection, the relic density of dark matter and the links with collider physics. The SuperIso Relic code was developed to provide a computational tool for different observables related to dark matter and particle physics. Initially dedicated to supersymmetry (SuperIso), the code is currently being developed to allow a flexible and generic implementation of all types of physics scenarios beyond the SM. In addition, we have studied the links with primordial cosmology, and shown that the discovery of new particles will provide information on the content of the Universe before primordial nucleosynthesis, despite the fact that this era is currently unobservable. In 2022, the DarkPACK code was published: interfaced with MARTY and SuperIso Relic, it automatically generates a numerical library of scattering amplitudes in a given model to calculate dark matter observables, such as the relic density.

Cosmology, Black Holes & Gravitational Waves

Our research includes the construction of alternative cosmological models, and the development of the public code AlterBBN. Our studies cover two directions: the consequences of the presence of cosmological scalars, and the existence of primordial black holes during primordial nucleosynthesis. For the first point, we have recently realized a composite model of inflation, using a construction similar to that of composite Higgs models, and we study string theory realizations of dark energy models, such as quintessence. The second point requires the study of Hawking radiation from Schwarzschild and Kerr black holes, and the BlackHawk code been developed, which is the first program allowing an automatic calculation of Hawking radiation from Schwarzschild and Kerr black holes. It allows us to continue studies in the field of cosmology, in particular for primordial black holes, and astroparticle physics, with the design of a new analysis to observe Hawking radiation with astroparticle physics experiments. Combined with the AlterBBN code, it also allows us to study the impact of primordial black holes or cosmological scalar fields on Big Bang nucleosynthesis.

We also developed an effective theory approach to include quantum corrections to the classical Schwarzschild geometry, and we studied the theoretical impact of extra dimensions and the “weak gravity conjecture” on quasi-normal modes of black holes.

Black holes are also studied in the context of gravitational waves and the possibility of peculiar gravitational signatures in some exotic models (e.g. boson stars) or alternative gravitational theories (LQG, tensor scaling theories, etc.).

The detection of gravitational waves provided the first firm observational constraint on the radii of neutron stars, thanks to the tidal deformability measured during the last orbits of the “inspiral” merger phase. We found that modern nuclear physics-based calculations of the equation of state of dense neutron-rich matter predict radii that are compatible, but more restrictive than that of GW170817. We also determined how improved constraints from future observations can provide new insights into dense matter and possible phase transitions in the neutron-star core.

Current Activities

We plan to produce simulations of kilonovae with state-of-the-art nuclear input. This will allow us to study multi-messenger signals emitted by kilonovae, such as GWs. We will also have a new tool to study the continuous emission of GWs by neutron stars. These calculations provide a perfect framework for a close collaboration with the VIRGO and Observational Cosmology groups at IP2I. Modeling the nucleosynthesis r-process existing in the ejected matter offers a possibility of linking with the expertise of nuclear theorists and nuclear experimenters at IP2I. Questions related to dense matter also allow a decompartmentalization between nuclear physics and hadron physics. More generally, the modeling of kilonovae and, perhaps in the future, core-collapse supernovae, could animate an active research program in the laboratory, also including astroparticle physics and cosmology.

N.B.: Sections marked with an asterisk require updating.

Formal Physics

The problem of a UV completion to quantum gravity motivated the development of string theory. The search for a non-perturbative formulation, the “M-Theory”, is still an active field of research today. However, recent applications of string theory go far beyond its original framework. They are at the origin of many formal results in field theory, which have allowed important breakthroughs in understanding strongly coupled interactions in supersymmetric “toy” theories, such as with the AdS/CFT correspondence or the electric-magnetic duality. String theory has also stimulated the study of non-local and/or non-commutative field theories.

Superspace, Higher-Order Corrections & Fermionic Condensates*

Contact : D. TSIMPIS

The effective action of M-theory/string theory admits an infinite tower of derivative corrections, playing a crucial role in areas such as black holes, cosmology and AdS/CFT duality. We have applied superspace methods to constrain the form of M-theory invariants. The developed tools have been used to determine the quartic fermion terms of IIA supergravity and their impact on the search for de Sitter solutions.

Flux Compactification, NATD & Coherent Truncations*

Contact : D. TSIMPIS

Flux compactification (FC) refers to the most general configuration in which the different tensor fields of string theory are activated, which allows to solve the “moduli problem”. We have used generalized geometry and G-structures to discover some periodicities and general features of FC backgrounds. These tools have also been used to shed light on non-Abelian T-duality, and to construct consistent truncations admitting de Sitter solutions.

Small Strings & U-Duality*

Contact : S. HOHENEGGER

Small string theories are a class of complete, nonlocal, ultraviolet interacting quantum theories in six (or fewer) dimensions. Many of these theories lack a Lagrangian description and are therefore notoriously difficult to describe with field theory methods alone. However, their connection with string theory provides us with many new approaches and tools to analyze the nonperturbative aspects of these theories. In a series of works, we have shown that various incarnations of string U-duality lead to remarkable dualities and symmetries between these gauge theories, which are intrinsically nonperturbative in nature. These symmetries allow us to better understand gauge theories, as well as to construct new theories. We will continue this approach, focusing in particular on nonperturbative dualities between theories with different matter and gauge contents.

Monodromies in One-Loop String Amplitudes*

Contact : S. HOHENEGGER

The scattering amplitudes at the N-point tree level in open string theory are described as correlation functions on the worldsheet disk. It is possible to establish monodromy relations that have been instrumental in the study (and solution) of the tree-level string scattering amplitudes. A generalization of these relations to one-loop amplitudes has been performed, yielding new relations between the scattering amplitudes of one-loop strings.

Toroidal compactification theories of supergravity to lower dimensions reveal the presence of exceptional symmetries, which cannot be explained by the Riemannian geometry of the inner manifold alone (or any other “conventional” symmetry within SUGRA itself). These are vestiges of the U-duality theory of strings (or M-theory), which hint at more complex structures at higher energy scales. Since these exceptional symmetries are difficult to explain within the framework of standard SUGRA theories, attempts have been made to extend the higher-dimensional versions of the latter in such a way as to make the appearance of the exceptional symmetries manifest upon compactification. The resulting theories are called exceptional field theories. The basic idea behind these constructions is an extended spacetime, which allows a geometric realization of the U-duality group. We explore different possibilities to formulate the (3,1) and (4,0) supergravity theories within the framework of exceptional field theories.

Field Theory Models in Ordinary & Noncommutative Spaces*

Contacts : F. GIERES & S. HOHENEGGER

We have provided an improvement procedure to construct a gauge-invariant, symmetric energy-momentum tensor. We have generalized Wong’s equations to noncommutative space and determined the properties of the energy-momentum tensor of gauge fields coupled to matter. We have studied field-theoretic models on deformed spaces and obtained local conservation laws and equilibrium equations for interacting fields on these spaces.

Nonlocalizable Field Theories

Contact : F. NORTIER

Nonlocalizable field theories have seen a resurgence of activity in the last 15 years, notably to solve the UV completion problem of gravity or the electroweak hierarchy problem. When nonlocality is introduced via form factors in the classical Lagrangian, an infinite tower of Ostrogradsky ghosts usually appears upon spontaneous symmetry breaking. We have recently developed a new formalism where form factors are introduced via a covariant star product between the fields that avoids this pitfall. We are currently working on linking these theories to UV completions by classicalization, exhibiting UV/IR mixing via the Vainshtein screening phenomenon.

N.B.: Page under construction.

Interdisciplinary

Renormalization & Epidemiology

Contact: S. HOHENEGGER

Epidemiology: an interdisciplinary science.

From Physics to Neurosciences

Contact: A. ARBEY

Artistic view of neural connections.

Public Codes

Contacts : A. ARBEY & F.N. MAHMOUDI

Numerical tools are nowadays essential to the community of physics of 2 infinities. The theoretical physics teams of IP2I Lyon are particularly involved in the development of public codes for phenomenology, with international recognition in this field.

SuperIso (2007)

Link: http://superiso.in2p3.fr

Author: F.N. MAHMOUDI

Description: Public code for computing flavor physics observables in the Standard Model and in new physics models.

SuperIso Relic (2009)

Link: http://superiso.in2p3.fr/relic

Authors: F.N. MAHMOUDI, A. ARBEY & G. ROBBINS

Description: SuperIso Relic is an extension of SuperIso for the calculation of the dark matter relic density and direct and indirect dark matter detection observables. A special feature of SuperIso Relic is that, in addition to the cosmological Standard Model, it allows the calculation of the relic density in alternative cosmological scenarios, thus allowing to test the influence of cosmological hypotheses.

AlterBBN (2012)

Link: https://alterbbn.hepforge.org/

Authors : A. ARBEY, J. AUFFINGER, K. HICKERSON & E. JENSSEN

Description: AlterBBN is a C program that calculates the abundances of elements predicted by Big Bang Nucleosynthesis (BBN). Different cosmological scenarios are implemented in AlterBBN, which can change the BBN predictions. In addition, AlterBBN is included in the SuperIso Relic package, so that alternative models can be tested using BBN constraints.

GAMBIT (2017)

Link: https://gambitbsm.org

Collaboration: The GAMBIT collaboration is made up of more than 70 international experts. F.N. MAHMOUDI is the coordinator of the physical part of flavors (FlavBit) and a member of the collaboration office.

Description: GAMBIT is a global fitting code for generic theories beyond the Standard Model, designed to allow rapid and easy definition of new models, observables, likelihoods and scanners, and to easily support new physics codes.

BlackHawk (2019)

Link: https://blackhawk.hepforge.org/

Authors: A. ARBEY & J. AUFFINGER

Description: BlackHawk is a public C program for computing Hawking evaporation spectra of any black hole distribution. This program allows users to compute primary and secondary spectra of stable or long-lived particles generated by Hawking radiation from the black hole distribution, and to study their evolution over time.

MARTY (2020)

Link: https://marty.in2p3.fr

Authors: G. UHLRICH, F.N. MAHMOUDI & A. ARBEY

Description: The goal of MARTY is to perform automatic calculations of amplitudes, cross sections, and Wilson coefficients in any new physics model. Some of its advantages are that MARTY is written entirely in C++, does not rely on proprietary code such as Wolfram Mathematica, and contains its own symbolic computation module (CSL), which can be used separately.

DarkPACK (2022)

Link: https://gitlab.in2p3.fr/darkpack/darkpack-public

Authors: M. PALMIOTTO, A. ARBEY & F.N. MAHMOUDI

Description: DarkPACK automatically generates a numerical library of scattering amplitudes in a given model to calculate dark matter observables, such as the relic density. DarkPACK is currently interfaced with MARTY and SuperIso Relic.

ANR Fundings

RELANSE (2024)

Complete Title: Lagrangians for finite nuclei and dense matter

Coordinator: Jérôme MARGUERON

Co-workers: Guy CHANFRAY & Hubert HANSEN

Duration: 48 months

Link: https://anr.fr/Project-ANR-23-CE31-0027

Description :

This ANR project RELANSE explores matter properties in a regime where the theory of the strong interaction, the quantum chromo-dynamics (QCD), could not be applied directly because of its non-perturbative nature at low-energy. This theory predicts however the onset of a chiral field emerging spontaneously at low-energy as well as the color confinement. These two properties imply that nucleons and mesons are the important degrees of freedom at low-energy. In this project, we develop an innovative, effective and relativistic approach describing chiral, nucleon and meson fields, and we contribute to consolidate the unified description of finite nuclei and neutron stars. The uniqueness of our project lies in the fact that we consistently analyze model predictions based on Hartree and Hartree-Fock approaches, which are adjusted to the same data. In particular, we address the question of the relativistic description of dense matter, where the sound speed, for instance, becomes comparable to the speed of light.
The originality of our project is to anchor the relativistic approaches employed in finite nuclei to the phenomenology of the quark substructure, e.g. results from Lattice QCD, the nucleon polarizability, VDM and quark model. In this way, the in-medium effects appear in our model in a very simple and traceable way compared to currently employed ones and our approach provides a robust guide to predict the properties of dense matter existing in neutron stars. We employ Bayesian statistics to compare the different scenarios to nuclear and astrophysical data, e.g., gravitational waves, x-ray emission from neutron stars. In this framework the theoretical, experimental and astrophysical uncertainties are employed in order to estimate the goodness of our new models.
For finite nuclei, we investigate the impact of the new models on ground state properties, e.g. energies, radii, neutron skin, as well as deformation, clustering, alpha decay and their experimental consequences. The novelty of our model is to possibly reduce the computing time of the present approaches, which employ density-dependent coupling constants. We estimate that our models can be as accurate as the present ones, and our project is instrumental to demonstrate it. We use all existing data to further constraint our models, we investigate the question of the understanding of the parity violating electron scattering puzzle from PREX and CREX experiments, and we address the description of exotic nuclei.
For neutron stars, we complement our relativistic models considering different scenarios for dense matter. Our methodology consists in exploring all various equations of state, which explore the current theoretical uncertainties in the existence of new phases of matter at high density, e.g. quark matter, hyperonic matter, quarkyonic matter. We then compare the predictions of these various scenarios to astrophysical data and we investigate to what extent these data indicate a preference for one of the scenarios describing the core of neutron stars.
The development of new effective Lagrangians helps us to address fundamental questions related to the strong force in dense matter and the Bayesian approach establishes the link between these fundamental properties and the existing data in finite nuclei and in neutron stars. We want to understand how the gaps between first principle, finite nuclei and neutron stars could be bridged and which effective properties of QCD are crucial in dense matter and low-energy. In addition, we will explore dense and finite temperature phases and produce new tables suitable for astrophysical simulations of core-collapse supenovae and kilonovae from neutron star mergers.
In addition, all data and codes from our project will be made publicly available (open-access) and a user-friendly interface in python will be provided to the community.

FlavBSM (2021)

Complete Title: Flavoured path Beyond the Standard Model of Particle Physics

Coordinator: Farvah Nazila MAHMOUDI

Duration: 60 months

Link: https://anr.fr/Project-ANR-21-CE31-0002

Description :

Despite its tremendous success, the shortcomings of the Standard Model (SM) of particle physics are well-known, and it is now commonly accepted in the particle physics community that going beyond the SM is a necessity. Search for physics beyond the SM started in the 1970’s, and no new physics signal has been discovered so far.
Recently, experimental results in flavour physics have exhibited a series of deviations from the SM predictions. These deviations in B meson decays, referred to as “flavour anomalies”, have been growing with time both in terms of statistical significance and in terms of internal consistency. We may therefore be on the verge of the discovery of New Physics (NP).
The FlavBSM proposal aims at understanding the origin of the discrepancies, and determining the underlying new physics model. This objective can be achieved by following three complementary research axes.
The first axis concerns precise calculations of the exclusive semileptonic B decays, and more specifically the calculation of the nonlocal hadronic effects. This constitutes an important challenge in the field, and a necessary step in order to unambiguously distinguish between SM hadronic effects and NP phenomena.
The second axis concerns the design and study of NP models. For this, we will consider not only effective field theory approaches, but also simplified models, based on which we will finally design and study well-motivated “complete” NP models, extending the validity range of the models far beyond the previous effective descriptions.
The third axis consists in software development to study the phenomenological implications of the flavour data. We aim in particular at an automatic calculation of the flavour observables in any NP model, and we will create new tools and techniques to perform statistical analyses and exploration of the parameter spaces of NP models, using simultaneously the constraints from the different sectors of particle physics. The first steps in this direction have already been successfully taken by the coordinator.
This project proposes therefore a full program to address the question of flavour anomalies in its generality. Understanding the origin of flavour anomalies is extremely important for a deeper understanding of fundamental interactions. The determination of the underlying new physics theory will constitute a major step in particle physics, providing directions towards the discovery of new particles. In addition, the project will provide new techniques, calculations and public computing tools to the community which will remain useful independently of the flavour anomalies.

NEWFUN (2019)

Complete: New energy functional for heavy nuclei

Coordinator: Michael BENDER

Co-worker: Karim BENNACEUR

Duration: 36 months

Link: https://anr.fr/Projet-ANR-19-CE31-0015

Description :

The project aims at the improved theoretical modelling and consistent interpretation of experimental data on very heavy and superheavy atomic nuclei with charge numbers Z greater than 82 and neutron numbers N beyond 126. These finite self-bound systems, many of which owe their very existence to quantal shell effects, exhibit a rich phenomenology of excitation and decay modes that are governed by the competition between the strong nuclear interaction, Coulomb repulsion, surface effects, and quantal shell structure of single-particle states. The available experimental data begin to reveal a consistent picture of their structure in terms of deformed shapes and shells, which at present, however, is not yet satisfactorily described by purely microscopic models. The main deficiency that has been clearly identified, and which is common to all presently available types of effective interactions, concerns the distance between single-particle levels near the Fermi energy. While global trends of observables are unaffected, the description of individual features of specific nuclei is in many cases lacking.

The goal of our project is to arrive at an unprecedented level of accuracy for the theoretical description of very heavy and superheavy nuclei through the adjustment of an effective interaction containing qualitatively new and hitherto unused higher-order terms. The fit of its parameters will take into account information about relevant properties of states of heavy nuclei and be accompanied by an analysis of statistical errors. The resulting interactions will subsequently be employed in systematic symmetry-unrestricted self-consistent mean-field calculations of a wide spectrum of observables of interest addressed in in-beam gamma-ray and conversion-electron spectroscopy, implanted-ion decay spectroscopy, and laser spectroscopy. The results then can be used for the planning and evaluation of experiments at existing and future heavy-ion-beam facilities.

We expect this project to make a decisive contribution to the progress in the theoretical description of the heaviest elements that will expand our understanding of these systems.

Awards & Distinctions

CNRS Medals

Silver

2021: Michael BENDER

Institut Universitaire de France (IUF)

Senior Members

2023: Farvah Nazila MAHMOUDI

2013: Aldo DEANDREA

Junior Members

2016: Alexandre ARBEY

2014: Farvah Nazila MAHMOUDI

Other Awards & Distinctions

Chevalière de la Légion d’honneur (2015): Magda ERICSON

Prix Thibaud (Académie des sciences, belles lettres et arts de Lyon, 1993): Guy CHANFRAY

Prix Gay-Lussac Humboldt (1992): Magda ERICSON

Prix Paul Marguerite de la Charlonie (Académie des sciences française, 1987): Magda ERICSON

Chevalière de l’ordre des Palmes académiques (1978): Magda ERICSON