Description:

The N-jettiness subtraction scheme

Andrea Isgrò, Graduate Student

abstract: The increasing experimental precision in Standard Model measurements at the Large Hadron Collider requires equally precise theoretical predictions. All theoretical predictions for cross sections in Quantum ChromoDynamics are perturbative series in the strong coupling constant. The Leading Order and Next-to-Leading Order of such series are known for all the relevant processes, while the NNLO still represents a challenge. In my talk, I first review why we really need NNLO predictions and why they are so hard to compute. Then, I present the N-jettiness subtraction scheme: a tool that has recently allowed us to compute for the first time NNLO cross sections for processes with 1 jet in the final state. Finally, I show how the method can be improved by analytically computing power corrections to the SCET (Soft-Collinear Effective Theory) factorization formula.

Characterizing doping in cuprate superconductor Hg1201 with Nuclear Magnetic Resonance

Ingrid Stolt, Graduate Student

abstract: The cuprates are a class of materials that become superconducting when additional holes are introduced through doping. In the high-temperature cuprate superconductor HgBa2CuO4+δ (Hg1201) the dopant that induces superconductivity is oxygen. We have measured the Nuclear Magnetic Resonance (NMR) spectrum at the 199Hg site of several Hg1201 single-crystal samples of various hole doping concentration, δ. Our data reveal up to four distinct peaks in the 199Hg NMR spectra and the spectral weights of these peaks follow a binomial distribution dependence on δ. In this talk I will show these results and discuss their implications regarding the electromagnetic environment in the Hg-plane. I will also mention a measured linear dependence of the peak frequencies on doping that could be amenable to theoretical description.