Visualisation Room (201)
Lloyd Building
Trinity College Dublin
Time: 2:00 pm
| Date | Speaker | Institute | Title |
| 15 Nov 2011 | Nicolas Garron | University of Edinburgh | b-physics from lattice heavy quark effective theory
View abstract Heavy quark effective theory (HQET) is a natural framework to study hadrons with a b-quark. Following the method proposed and developed by the Alpha collaboration, HQET can be implemented non-perturbatively beyond the static approximation (including corrections in inverse of the heavy quark mass). I will show how this method can be applied to the computation of physical quantities like the b-quark mass, the heavy-light decay constant, or the mass splitting mB*-mB. Finally I will present some results obtained with nf=2 flavours of dynamical quarks. |
| 29 Nov 2011 | Rachel Dowdall | University of Glasgow |
The Upsilon spectrum and the determination of the lattice spacing from
lattice QCD including charm quarks in the sea
View abstract We give results for the Upsilon spectrum from lattice QCD using an improved version of the NRQCD action for b quarks which includes radiative corrections to kinetic terms at O(v^4 ) in the velocity expansion. We also include for the first time the effect of up, down, strange and charm quarks in the sea using 'second generation' gluon field configurations from the MILC collaboration. Using the Upsilon 2S-1S splitting to determine the lattice spacing, we are able to obtain the 1P-1S splitting to 1.4% and the Upsilon 3S-1S splitting to 2.4%. Our improved result for M(Upsilon)-M(eta_b) is 69(9) and we predict M(Upsilon(2S)-M(eta_b(2S))=35(3) MeV. We also calculate pi, K and eta_s correlators using the Highly Improved Staggered Quark action and perform a chiral and continuum extrapolation to give values for M(eta_s) and f(eta_s) that allow us to tune the strange quark mass as well as providing an independent and consistent determination of the lattice spacing. Combining the NRQCD and HISQ analyses gives mb/ms=54.6(2.5) and a value for the heavy qiark potential parameter of r_1=0.3208(26)fm. |
| TBD | Assumpta Parreno | University of Barcelona |
View abstract |
| 21 February 2012 | Paula Perez Rubio | University of Regensburg |
Charmed hadron spectroscopy for $N_f =2+1$
View abstract The spectroscopy of hadrons containing charm quarks has undergone a renaissance in recent years. The triggering point was the discovery of several new narrow charmonium resonances close to the $D \bar D$ thresholds and new narrow $D_s$ mesons close to the DK thresholds. More results are expected to appear in the next few years from currently running experiments, e.g. Belle, BES-III and LHC and the future PANDA experiment at the FAIR facility at the GSI. We present the studies on the spectra of charmonium and charm-light mesons, including higher spin states using Lattice QCD, as well as the current status of the studies on the singly and doubly charmed baryon spectroscopy. |
| 6 March 2012 | Dirk Hesse | University of Parma |
Automated Lattice Perturbation Theory and Its Application to HQET
View abstract I will present the pastor software package for automated lattice perturbation theory calculations in the Schr?dinger functional and discuss an application in heavy quark effective theory (HQET). In the first part of the talk I will focus on the algorithms that are used to automatically generate Feynman Diagrams up to one loop order for a common class of observables and vertices up to arbitrary order in the bare coupling for a rather general class of quark and gluon actions, with a trivial or Abelian background field. I will comment on how the two parts of the pastor package that deal with these tasks work together but also how the vertex generator may be used on its own. In the second part of the talk I will present a one loop calculation involving heavy quarks that was performed using pastor. The observable under investigation was proposed to be used in the HQET matching step. Perturbation theory presents a good method to study properties such as the mass dependence without big numerical effort and thus acts as a guide for further non-perturbative studies. |
| 20 March 2012 | Pietro Giudice | Swansea University |
TBA
View abstract |
| 10 April 2012 | Gergely Enrodi | University of Regensburg |
View abstract |
| 24 April 2012 | Mario Schroek | Karl-Franzens-Universitaet Graz |
Effects of the low lying Dirac modes on the spectrum of QCD
View abstract Chiral symmetry breaking in Quantum Chromodynamics is associated with the low lying spectral modes of the Dirac operator according to the Banks-Casher relation. Here we study how removal of a variable number of low lying modes from the valence quark sector affects the ground and excited state masses of hadrons in two flavor lattice QCD using chirally improved (CI) fermions. |
| 8 May 2012 | Christoph Hanhart | Institut fur Kernphysik, Julich and University of Bonn |
How to reveal the mysteries of strong QCD
View abstract Recent years have experienced significant advances in both the development of effective field theories (EFTs) as well as lattice technologies to deal with QCD in the non-perturbative regime. In the talk on a few examples it will be shown how to exploit synergies from EFT and lattice QCD to learn about how QCD works at low energies as well as how one may hunt for the physics beyond the Standard Model. |
| 30 May 2012 | Seyong Kim | Sejong University, Seoul, South Korea |
Nonrelativistic QC2D in a non-zero baryon density environment
View abstract The heavy quarkonium spectrum of Two Color QCD (QC2D) at non-zero quark chemical potential mu and temperature T with mu/T>>1 has been calculated in both S- and P-wave channels using a lattice non-relativistic formulation of QC2D. As mu is varied, the quarkonium spectra reveal three separate regions, corroborating previous findings that there are three distinct physical regimes of QC2D at low temperature and high baryon density: hadronic matter, quark/quarkyonic matter, and deconfined matter. The results are interpreted in terms of the formation of heavy-light Qq states in the two-color baryonic medium. |