14,864 research outputs found
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
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
Path integral quantization for massive vector bosons
A parity-conserving and Lorentz-invariant effective field theory of
self-interacting massive vector fields is considered. For the interaction terms
with dimensionless coupling constants the canonical quantization is performed.
It is shown that the self-consistency condition of this system with the
second-class constraints in combination with the perturbative renormalizability
leads to an SU(2) Yang-Mills theory with an additional mass term.Comment: 16 pages, 2 figures, REVTeX
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