Visualisation Room (201)
Lloyd Building
Trinity College Dublin
Time: 2:00 pm
| Date | Speaker | Institute | Title |
| 21 Sept 2010 | Andre Sternbeck | Universitaet Regensburg | The QCD Lambda parameter from Landau-gauge gluon and ghost correlations
View abstract |
| 15 March 2011 | James Zanotti | University of Edinburgh |
Determining Vus from semileptonic Kaon decays
View abstract One area where physics beyond the Standard Model is hoped to be seen is in precision calculations of the elements of the CKM quark mixing matrix. While the SM predicts that the matrix should be unitary, it is unable to predict the numerical values of the individual elements. This talk will focus on the progress being made by the UKQCD and RBC collaborations in calculating the semi-leptonic (Kl3) K --> pi form factor which allows for an accurate determination of the CKM matrix element |V_us|, and hence is an important ingredient for testing the unitarity of the CKM matrix. |
| 22 March 2011 | Jonna Koponen | University of Glasgow |
The D to K and D to pi semileptonic decay form factors from Lattice QCD
View abstract We present a new study of D semileptonic decay form factors on the lattice. We work with MILC N_f=2 lattices and use the Highly Improved Staggered Action (HISQ) for both the charm and the light valence quarks. We use both scalar and vector currents to determine the form factors f_0(q^2) and f_+(q^2) for D to pi and D to K semileptonic decays. |
| 5 April 2011 | Liuming Liu | TCD |
Singly and Doubly Charmed $J=1/2$ Baryon Spectrum from Lattice QCD
View abstract We compute the masses of the singly and doubly charmed baryons in full QCD using the relativistic Fermilab action for the charm quark. For the light quarks we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We use the low-lying charmonium spectrum to tune our heavy-quark action and as a guide to understanding the discretization errors associated with the heavy quark. Our results are in good agreement with experiment within our systematics. For the $\Xi_{cc}$, we find the isospin-averaged mass to be $M_{\Xi_{cc}} = 3665 \pm17 \pm14\^{+0}_{-78}$~MeV; the three given uncertainties are statistical, systematic and an estimate of lattice discretization errors, respectively. In addition, we predict the mass splitting of the (isospin-averaged) spin-1/2 $\Omega_{cc}$ with the $\Xi_{cc}$ to be $M_{\Omega_{cc}} - M_{\Xi_{cc}} = 98 \pm9 \pm22\pm13$~{MeV} (in this mass splitting, the leading discretization errors are also suppressed by $SU(3)$ symmetry). Combining this splitting with our determination of $M_{\Xi_{cc}}$ leads to our prediction of the spin-1/2 $\Omega_{cc}$ mass, $M_{\Omega_{cc}} = 3763\pm19\pm26\^{+13}_{-79}$~{MeV}. |
| 19 April 2011** | Justin Foley | University of Utah |
Tuning improved anisotropic actions for Lattice QCD
View abstract Lattice regularisations of QCD provide a framework for non-perturbative studies of the strong interaction. A number of different discretisation schemes are in common use in current simulations, each with its own practical advantages and technical challenges. In this talk, we describe the tuning, using weak-coupling perturbation theory, of the anisotropic clover quark action and Symanzik-improved gluon action used in the simulations of the Hadron Spectrum Collaboration. The quark action is constructed from stout-smeared spatial links, which complicates these calculations considerably. We focus in particular on the determination of the action parameters which fix the aspect ratio, and show results for varying quark masses and smearing-parameter choices. |
| 3 May 2011 | Carleton DeTar | University of Utah/University of Glasgow |
High Temperature QCD from Lattice Gauge Theory: Recent Results
View abstract At extremely high temperatures and densities, strongly interacting matter undergoes a dramatic transition to a quark gluon plasma state. Studying the properties of this state of matter is a major goal of experiments at heavy-ion colliders. Numerical simulation of lattice gauge theory provides the only method for obtaining ab initio nonperturbative QCD predictions for the behavior of matter at high temperatures and low densities. In the past few years we have made considerable progress in removing the most important lattice cutoff effects, and we are starting to make confident predictions for the transition temperature, equation of state, and other quantities of importance for analyzing measurements of heavy ion collisions. This talk is meant for nonspecialists with an interest in the properties of strongly interacting matter at extreme temperatures. I will introduce briefly the simulation methods, and then discuss contemporary issues, including recent results from the HotQCD collaboration. |