Decay widths and scattering processes in massive QED2_2

Using mass perturbation theory, we infer the bound-state spectrum of massive QED$_2$ and compute some decay widths of unstable bound states. Further, we discuss scattering processes, where all the resonances and particle production thresholds are properly taken into account by our methods.Comment: Latex file, 5 pages, 8 ps-figures & 1 style-file; written version of a talk given at the QCD97 conference in Montpellier, Franc

Integrating evidence-based dentistry concepts throughout pre-doctoral dental curriculum

Evidence-based dentistry (EBD), an evolving educational tool that started its rise in the late 1990’s and early 2000’s, is being used more every year in dentistry. EBD combines the most current scientific and clinical evidence with the dentists’ expertise and the patients’ needs and preferences to formulate the best option to treat the patient. Since patients are taking more time to research their oral health issues before seeing their dentists, the dentists and the dental team must be prepared for all types of questions. Having the tools necessary to understand the latest and most significant research allows dental professionals to consistently educate themselves. However, there is no independent committee that handles the current issues facing dentistry. Using the topic of asymptomatic removal of third molars as a framework for EBD education, it can be used to help improve how schools educate their students. It is important that both the dental community and the public understand the scientific literature behind the removal of third molars because the existing practice of removing third molars without adverse symptoms is not statistically supported. Unfortunately, there is not enough evidence in favor of either side of the situation. Major databases, like PubMed, contain very little research on the asymptomatic removal of third molars, and those studies were not done recently. For EBD to be successful in dentistry, it must function in the clinical environment, but initial training in the concepts of EBD must start during pre-doctoral education. The dental practitioner still must rely on his or her own experience, but the patient must also trust his or her dentist. EBD is based on trust because it is based on the trust you have demonstrated through your skills and your usage of all available resources. If the dentist can compile pertinent scientific data and information to share with the patient and make the best decision together, then the use of EBD will be beneficial to the field of dentistry

Decay widths in the massive Schwinger model

By a closer inspection of the massive Schwinger model within mass perturbation theory we find that, in addition to the $n$-boson bound states, a further type of hybrid bound states has to be included into the model. Further we explicitly compute the decay widths of the three-boson bound state and of the lightest hybrid bound state.Comment: 8 pages, Latex file, no figure

Two-dimensional Chiral Anomaly in Differential Regularization

The two-dimensional chiral anomaly is calculated using differential regularization. It is shown that the anomaly emerges naturally in the vector and axial Ward identities on the same footing as the four-dimensional case. The vector gauge symmetry can be achieved by an appropriate choice of the mass scales without introducing the seagull term. We have analyzed the reason why such a universal result can be obtained in differential regularization.Comment: 9 pages, RevTex, no figures, a mistake in the massive case pointed out by the referee is correcte

Normalization of the chiral condensate in the massive Schwinger model

Within mass perturbation theory, already the first order contribution to the chiral condensate of the massive Schwinger model is UV divergent. We discuss the problem of choosing a proper normalization and, by making use of some bosonization results, we are able to choose a normalization so that the resulting chiral condensate may be compared, e.g., with lattice data.Comment: Latex file, 8 pages, 1 figure, needed macro: psbox.te

The Schwinger Mass in the Massive Schwinger Model

We derive a systematic procedure to compute Green functions for the massive Schwinger model via a perturbation expansion in the fermion mass. The known exact solution of the massless Schwinger model is used as a starting point. We compute the corrections to the Schwinger mass up to second order.Comment: Latex, 7 pages, no figure

THE DYSON-SCHWINGER EQUATION FOR A MODEL WITH INSTANTONS - THE SCHWINGER MODEL

Using the exact path integral solution of the Schwinger model -- a model where instantons are present -- the Dyson-Schwinger equation is shown to hold by explicit computation. It turns out that the Dyson-Schwinger equation separately holds for every instanton sector. This is due to Theta-invariance of the Schwinger model.Comment: LATEX file 11 pages, no figure

Four-point Green functions in the Schwinger Model

The evaluation of the 4-point Green functions in the 1+1 Schwinger model is presented both in momentum and coordinate space representations. The crucial role in our calculations play two Ward identities: i) the standard one, and ii) the chiral one. We demonstrate how the infinite set of Dyson-Schwinger equations is simplified, and is so reduced, that a given n-point Green function is expressed only through itself and lower ones. For the 4-point Green function, with two bosonic and two fermionic external `legs', a compact solution is given both in momentum and coordinate space representations. For the 4-fermion Green function a selfconsistent equation is written down in the momentum representation and a concrete solution is given in the coordinate space. This exact solution is further analyzed and we show that it contains a pole corresponding to the Schwinger boson. All detailed considerations given for various 4-point Green functions are easily generizable to higher functions.Comment: In Revtex, 12 pages + 2 PostScript figure

The General Correlation Function in the Schwinger Model on a Torus

In the framework of the Euclidean path integral approach we derive the exact formula for the general N-point chiral densities correlator in the Schwinger model on a torusComment: 17 pages, misprints corrected, references adde

A New Finite-lattice study of the Massive Schwinger Model

A new finite lattice calculation of the low lying bound state energies in the massive Schwinger model is presented, using a Hamiltonian lattice formulation. The results are compared with recent analytic series calculations in the low mass limit, and with a new higher order non-relativistic series which we calculate for the high mass limit. The results are generally in good agreement with these series predictions, and also with recent calculations by light cone and related techniques