High Energy Physics

Final states involving hadronic jets are an important background to new physics processes in colliders, as well as a probe of QCD over a large range of energies. Because the physics of jets involves multiple energy scales, they are both complex theoretically and ideally suited to study using effective field theory techniques. In this talk I will discuss some recent progress in using effective field theory to describe the physics of jets.

It is usually assumed that dark matter direct detection is sensitive to a large fraction of the dark matter (DM) velocity distribution. I will explain an alternative form of dark matter-nucleus scattering which only probes a narrow range of DM velocities due to the existence of a resonance, a DM-nucleus bound state, in the scattering - resonant dark matter (rDM). The scattering cross section becomes highly element dependent, has increased modulation and as a result can explain the DAMA/LIBRA results whilst not being in conflict with other direct detection experiments. I will describe a simple model that realizes the dynamics of rDM, where the DM is the neutral component of a fermionic weak triplet whose charged partners differ in mass by approximately 10 MeV.

The simplest gravity duals for quantum critical theories with 'Lifshitz' scale invariance admit a marginally relevant deformation. We will explore the holographic renormalization of such theories, including this deformation. Additionally we explore how this holographic renormalization illuminates the physics of black holes in the qunatum critical regime.

When a pair of particles is produced close to threshold, they may form a bound state if the potential between them is attractive. Can we use such bound states to obtain information about new colored particles at the LHC? I will discuss the relevant issues using examples from the MSSM and other beyond the standard model scenarios.

In the context of AdS/CFT correspondence the AdS_3/CFT_2 instance of the duality stands apart from other well studied cases, like AdS_5/CFT_4 or AdS_4/CFT_3. One of the reasons is that the CFT side of this duality is not a theory of matrices but rather a two dimensional orbifold based on the group of permutations. In this talk we will discuss some aspects of this theory. In particular a diagrammatic language, akin to Feynman diagrams used for gauge theories, will be developed. Moreover, we will compute a large set of protected quantities in a certain symmetric product orbifold CFT, and show that these are elegantly given in terms of Hurwitz numbers.

Supersymmetry is a leading candidate for physics Beyond the Standard Model. However, a tree level in the Minimal Supersymmetric Standard Model the Higgs boson should be lighter than the Z boson. LEP did not discover the Higgs boson, so typically large radiative corrections are required to push the Higgs above the LEP lower limit, leading to fine tuning issues. In this talk I will describe how to avoid limits from the searches at LEP and discuss a potential early signal of a 90 GeV Higgs at the LHC.

The top quark is the heaviest known type of quark, and possibly the last. Particle physicists sometimes refer to it as the "truth” quark, not always with tongue in cheek. The top quark might be just an ordinary quark, no stranger than the "strange" one, but it might hold the key to major questions of Nature through its connection to the origin of mass, the Higgs boson, and cosmic dark matter. At the Fermi National Accelerator Laboratory outside Chicago, hundreds of these heavy quarks have been observed and some first snapshots of their behavior have been obtained. At the Large Hadron Collider at CERN, millions of the heavy quarks will be produced. This lecture will review current knowledge of the top quark and explain how this knowledge has been obtained through experiments at the giant particle accelerators. Future experiments, which might reveal the top quark's deeper mysteries, will also be described.

I will describe a new connection between supersymmetry, geometry and computer science. An exploration of the equations of supersymmetry has revealed a geometrical sub-structure whose classification depends on self-dual error correcting codes.

The BCFW recursion relations define Yang-Mills and gravity amplitudes in terms of lower-point amplitudes. I will discuss several connections between the internal consistency of this recursive definition and the allowed interactions of massless, higher-spin particles.