Effective Field Theory of the Single-Nucleon Sector

We address the issue of a consistent power counting scheme in manifestly Lorentz-invariant baryon chiral perturbation theory. We discuss the inclusion of vector mesons in the calculation of the nucleon electromagnetic form factors. We comment on the chiral expansion of the nucleon mass to order O(q**6).Comment: 4 pages, talk at "Chiral Symmetry in Hadron and Nuclear Physics" (Chiral 07), Osaka, Japan, 13-16 Nov. 200

How to define physical properties of unstable particles

In the framework of effective quantum field theory we address the definition of physical quantities characterizing unstable particles. With the aid of a one-loop calculation, we study this issue in terms of the charge and the magnetic moment of a spin-1/2 resonance. By appealing to the invariance of physical observables under field redefinitions we demonstrate that physical properties of unstable particles should be extracted from the residues at complex (double) poles of the corresponding S-matrix.Comment: 11 pages, 3 figures, REVTeX

Cavity ringdown laser absorption spectroscopy and time-of-flight mass spectroscopy of jet-cooled silver silicides

The cavity ringdown technique has been employed for the first spectroscopic characterization of the AgSi molecule, which is generated in a pulsed laser vaporization plasma reactor. A total of 20 rovibronic bands between 365 and 385 nm have been measured and analyzed to yield molecular properties for the X, B, and C 2Sigma states of AgSi. A time-of-flight mass spectrometer simultaneously monitors species produced in the molecular beam and has provided the first direct evidence for the existence of polyatomic silver silicides. Comparison of the AgSi data to our recent results for the CuSi diatom reveals very similar chemical bonding in the two coinage metal silicides, apparently dominated by covalent interactions

Generalized orientations and the Bloch invariant

Abstract. For compact hyperbolic 3-manifolds we lift the Bloch invariant defined by Neumann and Yang to an integral class in K3(C). Applying the Borel and the Bloch regulators, one gets back the volume and the Chern-Simons invariant of the manifold. We also discuss the non-compact case, in which there appears a Z/2-ambiguity

Magnetic moment of the Roper resonance

The magnetic moment of the Roper resonance is calculated in the framework of a low-energy effective field theory of the strong interactions. A systematic power-counting procedure is implemented by applying the complex-mass scheme.Comment: 13 pages, 4 figure