Colloquia Archive 2013

I describe the analysis of the Standard Model of particle physics that has led a generation to believe that there is (accessible) physics beyond it. I also introduce the idea of the multiverse that has shaken that belief. Then I present the impact data from the Large Hadron Collider has ...

The present understanding of the properties of the recently discovered Higgs boson is discussed, based on the most recent results from the ATLAS experiment. These results include measurements of the mass, spin, production mechanisms, and couplings to fermions and bosons, and are based in most cases on the full data ...

The term Tensor Network States (TNS) encloses a number of families that represent different ansatzes for the efficient description of the state of a quantum many-body system. The first of these families, Matrix Product States (MPS), lies at the basis of Density Matrix Renormalization Group methods, which have become the ...

Variational principles of fluid turbulence offer an attractive alternative to numerical solution of the Navier-Stokes equation, especially for global climate studies. In this talk I'll discuss the conjecture of maximum kinetic energy dissipation and its application to turbulent channel flow and climate systems, as well as its theoretical basis ...

I will summarize the status of the Higgs boson after the first run of the LHC. The emphasis will be on interpreting the Higgs results as constraints on physics beyond the Standard Model. I will discuss a general effective Lagrangian that allows one to parametrize deviations of the Higgs couplings ...

With the successes of observational cosmology, a new window has opened up on to gravitational physics. By carefuly measuring the morphology and growth of structure in the Universe it may be possible to constrain general relativity on a completely new range of scales. It also allows us to explore a ...

The cellular world is inhabited by a myriad of microorganisms able to self- propel, including many bacteria, spermatozoa, ciliates, and plankton. Here, we focus on the biophysics of ciliary locomotion. Cilia are short slender whiplike appendages (a few microns long, one tenth of a micron wide) internally actuated by molecular ...

The average quantum physicist on the street would say that a quantum- mechanical Hamiltonian must be Dirac Hermitian (invariant under combined matrix transposition and complex conjugation) in order to guarantee that the energy eigenvalues are real and that time evolution is unitary. However, the Hamiltonian H=p^2+ix^3 ...

This talk will review a series of results obtained recently on the fluctuations of current in diffusive systems for several geometries: steady state obtained by contact with two reservoirs or two heat baths, system at equilibrium on a ring geometry, two systems at unequal temperatures which are connected at time ...

The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. In March of 2013, ESA and the Planck Collaboration released to the public a first complete set data products. I will review some of ...

"Frames" consisting of nodes connected pairwise by rigid rods or central-force springs can model systems as diverse as architectural structures, crystalline and amorphous solids, granular matter, and protein structures. The rigidity of these networks depends on their average coordination number z: If z is small enough, the system has internal ...

Observing new physics at hadron colliders requires a detailed description of multi-particle scattering events. It is not practical to evaluate Feynman diagrams directly for all significant processes. Moreover, adding all diagrams reveals many cancellations: scattering amplitudes in gauge theories such as QCD take remarkably simple forms. This simplicity is a ...

I will discuss three apparently unrelated subjects: (i) Wishart random matrices that appear in statistics and data analysis; (ii) Vicious Random Walkers model in statistical mechanics introduced by de Gennes and Fisher; (iii) pure Yang-Mills gauge theory in two dimensions on a sphere. The goal of this talk is to ...

I briefly review models of dark energy. These include models of a cosmological constant including those arising in string theory, and dynamical models where a scalar field may be responsible for the observed late time acceleration, through to the possibility that we are not fully in control of the gravity ...

Active Matter is composed of particles each supplied with energy which it dissipates, often resulting in systematic movement. Examples include living organisms, their motile constituents and some surprising mechanical and chemical analogues. These strongly driven systems offer a new arena in which to study the interplay of broken symmetry, conservation ...

Over the last decade, considerable effort has been expended to understand how subtle correlations in the pattern of hot- and cold-spots in the cosmic microwave background anisotropy, or the details of galaxy clustering, can teach us about physics at very high energies. I will review this effort and explain how ...

Predictions for scattering processes at particle colliders are done using perturbation theory, mostly using Feynman diagrams. Increasing precision requires increasing the order to which one computes, but sheer complexity puts a block on that road. Even worse, the corrections in many situations are too large for comfort. In this talk ...

I consider the non-equilibrium time evolution after a "quantum quench": an isolated many-particle system is initially prepared in its ground state and at time t=0 a parameter such as a magnetic field or an interaction strength is changed suddenly. I discuss realisations of such effects in systems of ultra- ...