An Improved Action for Heavy Quarks

We extend the Fermilab method for heavy quarks to include all interactions of dimension six in the action. We discuss a subtlety in the power counting, which implies that, for heavy quarks, certain interactions of dimension seven are commensurate with some of those of dimension six. We then present tree-level matching conditions obtained from calculating the Compton scattering amplitude for (lattice) QCD. When the matching conditions have been applied, the improved action removes (tree-level) discretization errors of order $a^2\bm{p}^3/m_Q$ and $a^3\bm{p}^3$.Comment: 1+5 pp., contribution to Lattice 2006(Quark Masses, Gauge Couplings, and Renormalization

A Solution to Matching with Preferences over Colleagues

We study many-to-one matchings, such as the assignment of students to colleges, where the students have preferences over the other students who would attend the same college. It is well known that the core of this model may be empty, without strong assumptions on agents' preferences. We introduce a method that finds all core matchings, if any exist. The method requires no assumptions on preferences. Our method also finds certain partial solutions that may be useful when the core is empty.Matching markets, Core, Lattice, Gale-Shapley algorithm

Why blame?

We provide experimental evidence that subjects blame others based on events they are not responsible for. In our experiment an agent chooses between a lottery and a safe asset; payment from the chosen option goes to a principal who then decides how much to allocate between the agent and a third party. We observe widespread blame: regardless of their choice, agents are blamed by principals for the outcome of the lottery, an event they are not responsible for. We provide an explanation of this apparently irrational behavior with a delegated-expertise principal-agent model, the subjects’ salient perturbation of the environment

DNA Typing Compatibility with a One Step Saliva Screening Test

Screening a substrate for bodily fluids is an extremely important step for locating areas that may contain DNA. Several different methods have been developed for saliva (1). The Phadebas® Forensic Press (PFP) test is a presumptive saliva test that utilizes a preloaded paper that will react with the enzyme amylase, a component of saliva (2-5). Because of its ability to screen for amylase while simultaneously locating stains, the PFP may prove to be an effective, rapid method for screening. However it is important to assess whether the PFP introduces any inhibitors (7) to downstream processing such as PCR amplification. Based on previous studies, we hypothesize that the PFP will provide a rapid and sensitive method for locating multiple saliva stains simultaneously, without introducing inhibitors to DNA profiling. To test the limitations of PFP as well as evaluated its effects on DNA profiling we first created a dilution series of saliva ranging from neat to 1:5000. After this we preformed sensitivity tests on an indirect method, UV degraded samples and washed samples as well as with bodily fluid mixtures. Once all sensitivity tests were done, cuttings were taken from the substrate and PFP paper and analyzed for DNA. Tests found that the sensitivity ranges of the PFP were between 1:10 and 1:1000, indirect tests were less sensitive than direct, all bodily fluid mixtures were detected, and UV degraded samples took more time to react. In addition our DNA results confirmed our hypothesis that PFP does not inhibit DNA and is a useful method for locating stains. This project was funded by NSFREU Grant DBI 1262832

Engineering nonlinear response of nanomaterials using Fano resonances

We show that, nonlinear optical processes of nanoparticles can be controlled by the presence of interactions with a molecule or a quantum dot. By choosing the appropriate level spacing for the quantum emitter, one can either suppress or enhance the nonlinear frequency conversion. We reveal the underlying mechanism for this effect, which is already observed in recent experiments: (i) Suppression occurs simply because transparency induced by Fano resonance does not allow an excitation at the converted frequency. (ii) Enhancement emerges since nonlinear process can be brought to resonance. Path interference effect cancels the nonresonant frequency terms. We demonstrate the underlying physics using a simplified model, and we show that the predictions of the model are in good agreement with the 3-dimensional boundary element method (MNPBEM toolbox) simulations. Here, we consider the second harmonic generation in a plasmonic converter as an example to demonstrate the control mechanism. The phenomenon is the semi-classical analog of nonlinearity enhancement via electromagnetically induced transparency.Comment: 10 pages, 6 figure

Spectral functions of charmonium from 2 flavour anisotropic lattice data

The spectral functions of QCD can give us insight into properties of hadrons, and they are useful in probing the QCD vacuum. I will discuss the correlators and spectral functions of charmonium in high temperature two flavour QCD. The spectral functions have been obtained using the Maximum Entropy Method from anisotropic lattice data using the conserved vector current. This work has been done as part of the FASTSUM collaboration. We find that the spectral functions for zero momentum are stable. At non-zero momentum the spectral functions are less stable but still produce resonance and transport peaks. This work is part of our programme to calculate the heavy quark diffusion constant.Comment: 7 pages, 5 figures, 31st International Symposium on Lattice Field Theory LATTICE 201

Heavy-quark meson spectrum tests of the Oktay-Kronfeld action

The Oktay-Kronfeld (OK) action extends the Fermilab improvement program for massive Wilson fermions to higher order in suitable power-counting schemes. It includes dimension-six and -seven operators necessary for matching to QCD through order ${\mathrm{O}}(\Lambda^3/m_Q^3)$ in HQET power counting, for applications to heavy-light systems, and ${\mathrm{O}}(v^6)$ in NRQCD power counting, for applications to quarkonia. In the Symanzik power counting of lattice gauge theory near the continuum limit, the OK action includes all ${\mathrm{O}}(a^2)$ and some ${\mathrm{O}}(a^3)$ terms. To assess whether the theoretical improvement is realized in practice, we study combinations of heavy-strange and quarkonia masses and mass splittings, designed to isolate heavy-quark discretization effects. We find that, with one exception, the results obtained with the tree-level-matched OK action are significantly closer to the continuum limit than the results obtained with the Fermilab action. The exception is the hyperfine splitting of the bottom-strange system, for which our statistical errors are too large to draw a firm conclusion. These studies are carried out with data generated with the tadpole-improved Fermilab and OK actions on 500 gauge configurations from one of MILC's $a\approx0.12$~fm, $N_f=2+1$-flavor, asqtad-staggered ensembles.Comment: 12 pages, 5 figure