Deutsches Elektronen-Synchrotron Desy

N =1 supersymmetric Yang-Mills theory on the lattice

University of Munster, Institute for Theoretical Physics,Wilhelm-Klemm-Str. 9, D-48149 Munster, GermanyE-mail:munsteg@uni-muenster.deNumericalsimulations of supersymmetrictheorieson the lattice are intricate and challengingwithrespect to their theoretical foundations and algorithmic realisation. Nevertheless, the simulationsof a four-dimensional supersymmetric gauge theory have made considerable improvements overthe recent years. In this contributionwe summarise the results of our collaborationconcerningthemass spectrum of this theory. The investigation of systematic errors allows now a more preciseestimate concerningthe expected formationof supersymmetricmultiplets of the lightest particles.These multiplets contain flavour singlet mesons, glueballs , and an additional fermionic state.31st International Symposium on Lattice Field Theory LATTICE 2013July 29 - August 3, 2013Mainz, Germany

Determination of the spin-dependent potentials with the multi-level algorithm

The spin-dependent corrections to the static interquark potential are relevant to describing the fine and hyper-fine splittings of the heavy quarkonium spectra. We investigate these corrections in SU(3) lattice gauge theory with the Polyakov loop correlation function as the quark source by applying the multi-level algorithm. We observe remarkably clean signals for the spin-dependent potentials up to intermediate distances.

Marking up lattice QCD configurations and ensembles

QCDml is an XML-based markup language designed for sharing QCD configurations and ensembles world-wide via the International Lattice Data Grid (ILDG). Based on the latest release, we present key ingredients of the QCDml in order to provide some starting points for colleagues in this community to markup valuable configurations and submit them to the ILDG.

The gluino-glue particle and relevant scales for the simulations of supersymmetric Yang-Mills theory

Supersymmetric Yang-Mills theory is in several respects different from QCD and pure Yang-Mills theory. Therefore, a reinvestigation of the scales, at which finite size effects and lattice artifacts become relevant, is necessary. Both, finite size effects and lattice artifacts, induce a breaking of supersymmetry. In view of the unexpected mass gap between bosonic and fermionic particles an estimation of these effects is essential.

Trajectory Length and Autocorrelation Times - N f = 2 simulations in the Schrödinger functional

Humboldt-Universitat, Institut fur PhysikNewtonstrasse 15, D-12489 BerlinA status report is presented on the large-volume simulations in the Schrodinger functional withtwo flavours of O( a) improved Wilson quarks performed by the ALPHA collaboration. Thephysics goal is to set the scale for the computation of the fundamental parameters of QCD. Inthis talk the emphasis is on aspects of the Hybrid Monte-Carlo algorithm, which we use with(symmetric) even-odd and Hasenbusch preconditioning. We study the dependence of aucorrela-tion times on the trajectory length. The latter is found to be significant for fermionic correlators,the trajectories longer than unity performing better than the shorter ones.DESY 06-161HU-EP-06/28SFB/CPP-06-42XXIV International Symposium on Lattice Field TheoryJuly 23-28 2006Tucson Arizona, US

Octet baryon mass splittings from up-down quark mass differences

Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the neutron-proton, Sigma and Xi mass splittings of the baryon octet due to updown (and strange) quark mass differences. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Full details and numerical results are given in [1].

Probing the chiral phase transition of N_f=2 clover fermions with valence overlap fermions

Overlap fermions are a powerful tool for investigating the chiral and topological structure of the vacuum and the thermal states of QCD. We study various chiral and topological aspects of the finite temperature phase transition of N_f=2 flavours of O(a) improved Wilson fermions, using valence overlap fermions as a probe. Particular emphasis is placed upon the analysis of the spectral density and the localisation properties of the eigenmodes as well as on the local structure of topological charge fluctuations in the vicinity of the chiral phase transition. The calculations are done on 16^3x8 lattices generated by the DIK collaboration.