Topological Susceptibility on Dynamical Staggered Fermion Configurations

The topological susceptibility is one of the few physical quantities that directly measure the properties of the QCD vacuum. Chiral perturbation theory predicts that in the small quark mass limit the topological susceptibility depends quadratically on the pion mass, approaching zero in the chiral limit. Lattice calculations have difficulty reproducing this behavior. In this paper we study the topological susceptibility on dynamical staggered fermion configurations. Our results indicate that the lattice spacing has to be small, around a~0.1fm for thin link staggered fermion actions to show the expected chiral behavior. Our preliminary result indicates that fat link fermions, on the other hand, reproduce the theoretical expectations even on lattices with a~0.17fm. We argue that this is due to the improved flavor symmetry of fat link fermionic actions.Comment: 16 pages, 4 figure

Glueballs and the superfluid phase of Two-Color QCD

We present the first results on scalar glueballs in cold, dense matter using lattice simulations of two color QCD. The simulations are carried out on a $6^3 \times 12$ lattice and use a standard hybrid molecular dynamics algorithm for staggered fermions for two values of quark mass. The glueball correlators are evaluated via a multi-step smearing procedure. The amplitude of the glueball correlator peaks in correspondence with the zero temperature chiral transition, $\mu_c = m_\pi/2$, and the propagators change in a significant way in the superfluid phase, while the Polyakov loop is mearly insensitive to the transition. Standard analysis suggest that lowest mass in the $0^{++}$ gluonic channel decreases in the superfluid phase, but these observations need to be confirmed on larger and more elongated lattices These results indicate that a nonzero density induces nontrivial modifications of the gluonic medium.Comment: 26 pages, 13 figures; discussions and one figure added; to appear in EPJ

Context-aware compliance checking

Organizations face more and more the burden to show that their business is compliant with respect to many different boundaries. The activity of compliance checking is commonly referred to as auditing. As information systems supporting the organization’s business record their usage, process mining techniques such as conformance checking offer the auditor novel tools to automate the auditing activity. However, these techniques tend to look at process instances (i.e., cases) in isolation, whereas many compliance rules can only be evaluated when considering interactions between cases and contextual information. For example, a rule like a paper should not be reviewed by a reviewer that has been a co-author cannot be checked without considering the corresponding context (i.e., other papers, other issues, other journals, etc.). To check such compliance rules, we link event logs to the context. Events modify a pre-existing context and constraints can be checked on the resulting context. The approach has been implemented in ProM. The resulting context is represented as an ontology, and the semantic web rule language is used to formalize constraints