The Large Hadron Collider (LHC) at CERN explores the frontier of particle physics by colliding protons. Quarks and gluons are abundantly produced in high-energy collisions and are a major handle to probe fundamental interactions and discover new physics. Practically, quarks and gluons are observed in the form of collimated showers of particles, called jets. We have established the current framework to reconstruct jets at the LHC. With the higher energies reached at the LHC, massive objects such as W/Z or Higgs bosons or the top quark can be produced boosted, that is with an energy much larger than their mass. When they decay via strong interactions, their decay products will be collimated, and they will be seen as a single jet. This is a shift from the standard paradigm where a "jet" is now a proxy for more than just a quark or a gluon. To maximise the LHC potential one must be able to isolate the rare boosted jets coming from the decay of massive objects from the much more frequent quarks and gluons. This is achieved by exploiting the substructure of the jets, i.e. the properties of their constituents. Jet substructure has been a growingly active field of research during Run I of the LHC, with many methods proposed, mainly by the theory part of the community, and many validations and measurements performed on the experimental side. Today, we therefore have evidence that jet substructure techniques work and help in identifying boosted jets. Currently, the methods are usually proposed and tested numerically, based on event simulated using Monte-Carlo event generators. This empirical approach suffers from severe limitations: it does not explain why a method works better than another; it makes it hard and time-consuming to explore vast parameter spaces and extrapolate across a wide energy range; it does not allow for robust estimations of the theoretical uncertainties; it does not explain subtle differences between Monte-Carlo simulations and actual experimental data and, above all, it shines no light on how to improve existing techniques. The objective of this project is to alleviate the above limitations by providing a first-principle understanding of jet substructure based on the theory of strong interactions. First, this means understanding existing techniques analytically. Our major goals are then to use this understanding to (i) develop new, optimised, jet substructure methods and (ii) provide precise calculations to estimate the theoretical uncertainties and gauge the robustness of each method. The analytic approach that we will use has been proven very successful in preliminary studies. This also means that our project is not only feasible but also very promising. Besides the main, crucial, application to boosted-objects identification, this project can also have more generic implications on optimisation of final-state information at the LHC such as pileup mitigation or jet vetoes. Furthermore, we shall also provide high-quality open-source software implementations of our tools in order to make them easily accessible by the relevant scientific community. Altogether, our project will bring the field of jet substructure to a new level. It will set the framework of this rapidly growing field for the next decade and beyond. This has an impact on a broad range of analyses at the LHC and will improve its discovery potential. The experience of the members of this team in jet physics puts us in a unique position to achieve our goals.

For decades we have tried to explain the value of the Higgs boson mass in terms of symmetry. We have expected new symmetries and the new particles realizing them, to appear, first at LEP, then at the Tevatron and finally at the LHC. After more than 40 years we have not observed them and the origin of the scale of weak interactions remains mysterious. In this proposal I argue for a complete change of perspective on the problem. The origin of the weak scale can be found at early times in the history of the Universe, but it leaves non-trivial traces in the laboratory today. I discuss how the value of the Higgs boson mass can be tied to the evolution of the Universe, developing a program to fully explore the experimental consequences of this possibility. The impact of such a change of perspective is far reaching: it changes sharply our understanding of the origin of the weak scale. It offers a completely new motivation for current and future cosmological experiments. The impact is profound also on the high energy physics experimental program since this class of ideas points to a number of new experiments and signatures, ranging from probes of long-range forces to new signatures at the LHC and at future colliders.

Large-N approaches are powerful methods to study quantum many body problems such as those encountered in solid state physics and correlated electron problems. These methods consist in generalizing the problem to an arbitrary number, N, of particle flavors. When N goes to infinity the different flavors decouple and the interaction terms become solvable (quadratic and mean-field like). The task is then to expend the physical properties in 1/N to approach the initial model of interest. When applied to quantum spin systems in dimension greater than one, this approach has proven to be very fruitful and has provided the basis of our current understanding of the highly quantum phases these systems, and spin liquids in particular. However, one cannot make reliable quantitative predictions about a given microscopic model without including the fluctuation (i.e. finite-N) effects, some of which are known to be related to gauge degrees of freedom. In this project we will revisit and expand one particular large-N limit of antiferromagnetic Heisenberg model, that based on the Schwinger boson representation [Sp(2N)]. The idea is to start from some systematic numerical exploration of the low-energy landscape defined by the self-consistent mean-field solutions. For N=infinity the system is “locked” into the global energy minimum of this landscape. On the other hand, for finite N, the system can explore the low-energy regions of this landscape, and local minima and saddle-points in particular. Our idea is to gain some insight about the finite-N physics from the detailed knowledge of the mean-field energy landscape. As a first concrete application of this idea, we plan to study some frustrated spin models which have a Z2 spin liquid phase for small enough value of the spin (and large enough N), such as the triangular or kagome Heisenberg models. Such Z2 spin liquids are known to host some particular elementary excitations, dubbed visons, and which correspond to Pi-flux vortices for the (emergent) Z2-gauge field. We will look for these vortex states as saddle-points in the mean-field landscape, study their correlations and energetics (gap). Characterizing the excited mean-field states in magnetically ordered phases is also part of our program. Then, by computing numerically some (imaginary) time-dependent saddle-points of the large-N theory we will have access to the dynamical properties of these visons. Indeed, such instanton calculations should give the tunneling amplitudes for a vison to hop from one lattice plaquette to another, and thus their dispersion relation. This will provide an effective Ising-gauge theory model describing the non-perturbative finite-N fluctuations, and which will allow to address quantitatively some important questions such as the possible critical value of N below which the vison may condense and give rise to quantum phase transition (typically toward a valence-bond crystal).

One of the central themes in modern day nuclear physics is the exploration of the structure of nuclei far from stability – the so-called “exotic” nuclei. Of particular interest is the light (A<40) neutron dripline region, which not only provides an ideal testing ground for many theoretical models of nuclear structure but also exhibits a number of unique phenomena, such as neutron haloes. Experimentally it has become possible in recent years to begin to access light unbound systems lying beyond the neutron dripline in this region and, as such, probe the evolution of structure into the continuum. The overall physics objectives of the EXPAND project are to undertake, using the unique opportunities offered by the recently commissioned RIBF facility at RIKEN (Saitama, Japan), the study of the structure and intrinsic correlations present in light neutron-rich nuclei lying at and beyond the neutron dripline and to search for exotic new phenomena, including resonance structures in multi-neutron systems such as the tetra-neutron. The choice of the RIBF as the venue for this work is a compelling one: high intensity primary beams (most notably 48Ca) coupled with the BigRIPS fragment separator allow for the production of the most intense secondary beams of light neutron dripline nuclei in the world – typically three or four orders of magnitude higher than any other facility. Moreover, in many cases, the RIBF is the only facility capable of producing these beams. In addition, the beam energies (~250 MeV/nucleon) are ideally matched, both experimentally and theoretically, to the reactions of interest – nucleon “knockout”, breakup and inelastic scattering. The investigations will be undertaken using kinematically complete measurements of the beam velocity reaction products – charged fragment and neutrons – arising from the in-flight decay of the system of interest. The detection of the charged fragment will be undertaken using the SAMURAI superconducting dipole and associated detectors. The present proposal focuses on developing the neutron detection and aims to provide us with a world class array to match the beams provided by the RIBF. Specifically it is planned to transform the existing neutron array (NEBULA) through the doubling of the number of scintillator walls – forming the “NEBULA-Plus” array – to enable 3 and 4 neutron detection capabilities, as well as augmenting dramatically the single and two-neutron detection efficiencies. As such, within the four year timeframe of the EXPAND project, 28O (Z=8, N=20), the only remaining unexplored doubly-magic nucleus yet to be observed will be investigated for the first time and its structure and multi-neutron correlations probed. In parallel, the “heavy” candidate two-neutron halo nuclei 29,31F and the associated unbound systems 28,30F will be explored. In addition, the search for multi-neutron correlations in the form of resonances in the 4n system will be pursued in combination with the study of the most neutron-asymmetric nucleus known, 7H and the four-neutron dissociation of 8He. These lines of research will continue well beyond the period of the grant whereby the investigation of heavier systems will be pursued. It is expected that a state-of-the-art physics programme with the NEBULA-Plus array will be maintained for at least 15 years. In summary, the EXPAND project will allow the highest intensity beams of light neutron dripline nuclei to be coupled with unique neutron detection capabilities, thus permitting the exploration of nuclear structure in the most exotic neutron-rich systems. The project will position us as leaders in the field for at least the next decade and provide an essential base, both technical and scientific, for extending these studies with the future European 3rd generation radioactive beam facility EURISOL.

Laterites are deep weathering covers of the critical zone that occupy 80% of the total soil-mantle volume of the Earth’s landscape and significantly participate to the global geochemical budget of weathering and erosion, and greenhouse gas consumption. Despite their factual importance on Earth surface, the timing of their formation and evolution in response to climatic and geodynamic forcing are still obscure. RECA project will address both the topics of "Functioning and evolution of climate, oceans and major cycles" and "Continental Surfaces: critical zone and biosphere" from ANR Axis 1 – Challenge 1., by reconstructing the influence of climate change laterites formation. The originality of the RECA project is to combine chronometric, weathering and climatic proxies developed in the recent years in order to build a comprehensive and predictive scenario of laterite formation and evolution. We will concentrate our effort on geodynamically stable Guyana Shield and Central Amazonia regions, where laterites formed through the whole Cenozoic and can be associated with major geomorphological units. This ambitious multidisciplinary project proposes, for the first time, to perform absolute dating of lateritic duricrusts associated to five episodes of planation in the South American subcontinent. We will date mineralogically well-identified populations of iron oxides and oxyhydroxides (hematite, goethite) and clays (kaolinites) by using (U-Th)/He, (U-Th)/Ne and electron paramagnetic resonance spectroscopy, respectively. These recent methods are appropriates because they can be applied to the most common secondary minerals found in laterites and span geological time scales. The inherent complexity of weathering materials, which may contain different populations of a same secondary mineral related to distinct stages of lateritization will be taken into account. The timing of duricrust formation will then be related to paleoclimatic conditions (temperature, rainfall) derived from a combination of geochemical or mineralogical indices and proxies: (i) at global scale, through, e.g., the known continental drainage curves; (ii) at a more regional scale through the intensity of weathering, the ratio hematite/goethite or O and H isotope systems of kaolinite and iron oxides and oxyhydroxides. A second task will associate non-conventional Li, Si and Fe isotopic methods that will help to decipher the evolution of weathering processes linked to the various stages of laterite formation. Coupling weathering budget and the ages of weathering profiles will yield average weathering and erosion rates, allowing comparison with other weathering environments or paleo-environments at the Earth surface. To tackle this ambitious task, the RECA project gathers an international consortium made of skilled researchers in the identification of lateritic soils, dating methods, environmental mineralogy; "traditional" and "non-traditional" stable isotope geochemistry, and modeling approaches of the formation of weathering profiles. The synergy of the identified teams offers the highest level of guarantee to lift off the identified scientific and technical barriers, giving access to yet hidden information on soil formation as a response to climate change through geological times.