DNA oligomers can nowadays be assembled to produce a large variety of nanometric constructs, via a cascade of self-assembly processes, each one guided by the length of complementary sequences of distinct DNA strands. In the seminar I will show that it is possible to build bulk quantities of DNA-made nanoparticles that closely match idealised colloids, transferring modern in-paper and in-silico intuitions into experimental realisations. I will show how unconventional collective behaviours, recently explored theoretically and numerically, can indeed be reproduced in the lab. Specifically I will discuss: (i) how to exploit limited valence interactions to suppress phase separation, enhancing the stability of the equilibrium gel phase; (ii) how to exploit competing interactions to generate a material that is fluid both at high and at low temperatures and a solid-like disordered open network structure in between and (iii) how to exploit bond-swap dynamics to create an all-DNA vitrimer.

We will explore the integrable non-linear sigma models obtained by reduction of 4D/5D gravitational theories to 2D, identify the Lax Pair system corresponding to the generator of the infinite integrals of motion, and map the solutions of this system to a Riemann-Hilbert matrix factorization problem, which we can explicitly factorize, thus generating solutions of the original 4D/5D gravity theory as well as identifying various solution generating symmetries in terms of elementary matrix operations.

Hard spheres are the simplest statistical mechanical model to describe particulate systems, such as atoms, colloids, and grains. Despite its simplicity, this model shows a rich phenomenology when compressed beyond the freezing point. Several scenarios have been proposed to describe the nature of arrested amorphous states at large densities, where both a glass transition (in colloidal systems) and a jamming transition (in granular systems) are observed. So far, however, none of these scenarios could be tested explicitly, because both experiments and computer simulations failed to thermalize the system in the density range where both transitions occur. Recently, we implemented a very efficient simulation algorithm that enabled us to thermalize systems of polydisperse hard spheres at unprecedently high densities, surpassing both experiments and previous simulations by several orders of magnitude. Here we use these numerical advances to demonstrate that the jamming transition cannot be the ultimate fate of dense hard spheres, and that a thermodynamic glass transition cannot be ruled out.

Ref.: "Equilibrium sampling of hard spheres up to the jamming density and beyond ", Phys. Rev. Lett. 116, 238002 (2016)

We consider quantization of a cosmological model in which matter is represented by a series of concentric spherical dust shells. It is shown that the distances between the shells have discrete spectra when they are timelike. Essential for seeing this discreteness is the use of global coordinates covering the entire phase space of the model. In particular, it explains why quantization of cosmological models which uses local values of fields as phase space variables doesn't reveal any discreteness.

The electric double layer is generally viewed as simply the boundary that interpolates between an electrolyte solution and a metal surface. Contrary to that view, molecular simulations show that the interface between ionic liquids and metallic electrodes can exhibit structures and fluctuations that are not simple reflections of surrounding bulk materials. This rich behavior is absent from a mean-field picture that averages over intraplanar structure. The charge of the electrode is screened by the interfacial fluid and induces subtle changes in its structure, which cannot be captured by the conventional Gouy-Chapman theory.

In recent years, we have performed molecular dynamics simulations on a variety of electrochemical systems  made of ionic liquids (either pure or mixed with acetonitrile), and electrodes of different geometries ranging from planar to nanoporous. A key aspect of our simulations is to use a realistic model for the electrodes, by allowing the local charges on the atoms to vary dynamically in response to the electrical potential caused by the ions and molecules in the electrolyte.

These simulations have allowed us to gain strong insight on the structure and dynamics of ionic liquids at electrified interfaces. From the comparison between graphite and porous CDC electrodes, we have elucidated the molecular mechanism at the origin of the increase of the capacitance enhancement in nanoporous carbons. The simulations also provide us the diffusion coefficients of the ions and the charging times for the full supercapacitor device. 

In the first part of the talk I will review the experimental and theoretical status of physics Beyond the Standard Model (SM) in the light of the LHC results of the recent years.
Then, motivated by the lack of signals of New Physics in indirect searches and by the fact that the SM possesses various accidental and approximate symmetries, I will talk about extensions of the SM that automatically preserve such symmetries. I will finally comment about cosmological as well as phenomenological implications of such a framework.

I review recent progress in understanding the dynamics of light self-interacting scalar fields in de Sitter space at low (superhorizon) momenta. In this regime, perturbation theory is plagued by secular/infrared divergences due to the gravitational amplification of long wavelength quantum fluctuation and a correct description requires resummation schemes and/or nonperturbative tools. I present recent advances based on solutions of the Dyson-Schwinger equations and on nonperturbative renormalization group techniques. The gravitationally enhanced infrared fluctuations trigger dramatic phenomena such as the radiative restoration of spontaneously broken continuous symmetries.