Non-renormalization theorems without supergraphs: The Wess-Zumino model

The non-renormalization theorems of chiral vertex functions are derived on the basis of an algebraic analysis. The property, that the interaction vertex is a second supersymmetry variation of a lower dimensional field monomial, is used to relate chiral Green functions to superficially convergent Green functions by extracting the two supersymmetry variations from an internal vertex and transforming them to derivatives acting on external legs. The analysis is valid in the massive as well as in the massless model and can be performed irrespective of properties of the superpotential at vanishing momentum.Comment: 20 pages, Latex, added acknowledgment

Axial Anomaly from the BPHZ regularized BV master equation

A BPHZ renormalized form for the master equation of the field antifiled (or BV) quantization has recently been proposed by De Jonghe, Paris and Troost. This framework was shown to be very powerful in calculating gauge anomalies. We show here that this equation can also be applied in order to calculate a global anomaly (anomalous divergence of a classically conserved Noether current), considering the case of QED. This way, the fundamental result about the anomalous contribution to the Axial Ward identity in standard QED (where there is no gauge anomaly) is reproduced in this BPHZ regularized BV framework.Comment: 10 pages, Latex, minor changes in the reference

Procedural Skills Training During Emergency Medicine Residency: Are We Teaching the Right Things?

Objectives: The Residency Review Committee training requirements for emergency medicine residents (EM) are defined by consensus panels, with specific topics abstracted from lists of patient complaints and diagnostic codes. The relevance of specific curricular topics to actual practice has not been studied. We compared residency graduates’ self-assessed preparation during training to importance in practice for a variety of EM procedural skills.Methods: We distributed a web-based survey to all graduates of the Denver Health Residency Program in EM over the past 10 years. The survey addressed: practice type and patient census; years of experience; additional procedural training beyond residency; and confidence, preparation, and importance in practice for 12 procedures (extensor tendon repair, transvenous pacing, lumbar puncture, applanation tonometry, arterial line placement, anoscopy, CT scan interpretation, diagnostic peritoneal lavage, slit lamp usage, ultrasonography, compartment pressure measurement and procedural sedation). For each skill, preparation and importance were measured on four-point Likert scales. We compared mean preparation and importance scores using paired sample t-tests, to identify areas of under- or over-preparation.Results: Seventy-four residency graduates (59% of those eligible) completed the survey. There were significant discrepancies between importance in practice and preparation during residency for eight of the 12 skills. Under-preparation was significant for transvenous pacing, CT scan interpretation, slit lamp examinations and procedural sedation. Over-preparation was significant for extensor tendon repair, arterial line placement, peritoneal lavage and ultrasonography. There were strong correlations (r>0.3) between preparation during residency and confidence for 10 of the 12 procedural skills, suggesting a high degree of internal consistency for the survey.Conclusions: Practicing emergency physicians may be uniquely qualified to identify areas of under- and over-preparation during residency training. There were significant discrepancies between importance in practice and preparation during residency for eight of 12 procedures. There was a strong correlation between confidence and preparation during residency for almost all procedural skills, re-enforcing the tenet that residency training is the primary locus of instruction for clinical procedures.[WestJEM. 2009;10:152-156.

On a class of embeddings of massive Yang-Mills theory

A power-counting renormalizable model into which massive Yang-Mills theory is embedded is analyzed. The model is invariant under a nilpotent BRST differential s. The physical observables of the embedding theory, defined by the cohomology classes of s in the Faddeev-Popov neutral sector, are given by local gauge-invariant quantities constructed only from the field strength and its covariant derivatives.Comment: LATEX, 34 pages. One reference added. Version published in the journa

Stickiness in Hamiltonian systems: from sharply divided to hierarchical phase space

We investigate the dynamics of chaotic trajectories in simple yet physically important Hamiltonian systems with non-hierarchical borders between regular and chaotic regions with positive measures. We show that the stickiness to the border of the regular regions in systems with such a sharply divided phase space occurs through one-parameter families of marginally unstable periodic orbits and is characterized by an exponent \gamma= 2 for the asymptotic power-law decay of the distribution of recurrence times. Generic perturbations lead to systems with hierarchical phase space, where the stickiness is apparently enhanced due to the presence of infinitely many regular islands and Cantori. In this case, we show that the distribution of recurrence times can be composed of a sum of exponentials or a sum of power-laws, depending on the relative contribution of the primary and secondary structures of the hierarchy. Numerical verification of our main results are provided for area-preserving maps, mushroom billiards, and the newly defined magnetic mushroom billiards.Comment: To appear in Phys. Rev. E. A PDF version with higher resolution figures is available at http://www.pks.mpg.de/~edugal

Hyperbolic outer billiards : a first example

We present the first example of a hyperbolic outer billiard. More precisely we construct a one parameter family of examples which in some sense correspond to the Bunimovich billiards.Comment: 11 pages, 8 figures, to appear in Nonlinearit

A Generalized Gauge Invariant Regularization of the Schwinger Model

The Schwinger model is studied with a new one - parameter class of gauge invariant regularizations that generalizes the usual point - splitting or Fujikawa schemes. The spectrum is found to be qualitatively unchanged, except for a limiting value of the regularizing parameter, where free fermions appear in the spectrum.Comment: 16 pages, SINP/TNP/93-1

Explicit Bosonization of the Massive Thirring Model in 3+1 Dimensions

We bosonize the Massive Thirring Model in 3+1D for small coupling constant and arbitrary mass. The bosonized action is explicitly obtained both in terms of a Kalb-Ramond tensor field as well as in terms of a dual vector field. An exact bosonization formula for the current is derived. The small and large mass limits of the bosonized theory are examined in both the direct and dual forms. We finally obtain the exact bosonization of the free fermion with an arbitrary mass.Comment: Latex, 7 page

Higher-order non-symmetric counterterms in pure Yang-Mills theory

We analyze the restoration of the Slavnov-Taylor (ST) identities for pure massless Yang-Mills theory in the Landau gauge within the BPHZL renormalization scheme with IR regulator. We obtain the most general form of the action-like part of the symmetric regularized action, obeying the relevant ST identities and all other relevant symmetries of the model, to all orders in the loop expansion. We also give a cohomological characterization of the fulfillment of BPHZL IR power-counting criterion, guaranteeing the existence of the limit where the IR regulator goes to zero. The technique analyzed in this paper is needed in the study of the restoration of the ST identities for those models, like the MSSM, where massless particles are present and no invariant regularization scheme is known to preserve the full set of ST identities of the theory.Comment: Final version published in the journa