466 research outputs found
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
Derivation of spontaneously broken gauge symmetry from the consistency of effective field theory II: Scalar field self-interactions and the electromagnetic interaction
We extend our study of deriving the local gauge invariance with spontaneous
symmetry breaking in the context of an effective field theory by considering
self-interactions of the scalar field and inclusion of the electromagnetic
interaction. By analyzing renormalizability and the scale separation conditions
of three-, four- and five-point vertex functions of the scalar field, we fix
the two couplings of the scalar field self-interactions of the leading order
Lagrangian. Next we add the electromagnetic interaction and derive conditions
relating the magnetic moment of the charged vector boson to its charge and the
masses of the charged and neutral massive vector bosons to each other and the
two independent couplings of the theory. We obtain the bosonic part of the
Lagrangian of the electroweak Standard Model as a unique solution to the
conditions imposed by the self-consistency conditions of the considered
effective field theory.Comment: 11 pp, 3 fig
Triviality of quantum electrodynamics revisited
Quantum electrodynamics is considered to be a trivial theory. This is based
on a number of evidences, both numerical and analytical. One of the strong
indications for triviality of QED is the existence of the Landau pole for the
running coupling. We show that by treating QED as the leading order
approximation of an effective field theory and including the next-to-leading
order corrections, the Landau pole is removed. Therefore, we conclude that the
conjecture, that for reasons of self-consistency, QED needs to be trivial is a
mere artefact of the leading order approximation to the corresponding effective
field theory.Comment: 3 pages, 2 figure
Complex mass renormalization in EFT
We consider an effective field theory of unstable particles (resonances)
using the complex-mass renormalization. As an application we calculate the
masses and the widths of the meson and the Roper resonance.Comment: 8 pages, 2 figures; Proceedings of 6th International Workshop on
Chiral Dynamics, 6-10 July 2009, Bern, Switzerlan
Chiral expansion of the nucleon mass to order q^6
We present the results of a complete two-loop calculation at order q^6 of the
nucleon mass in manifestly Lorentz-invariant chiral perturbation theory. The
renormalization is performed using the reformulated infrared renormalization,
which allows for the treatment of two-loop integrals while preserving all
relevant symmetries, in particular chiral symmetry.Comment: 6 pages, 2 figures, REVTeX
Improving the ultraviolet behavior in baryon chiral perturbation theory
We introduce a new formulation of baryon chiral perturbation theory which
improves the ultraviolet behavior of propagators and can be interpreted as a
smooth cutoff regularization scheme. It is equivalent to the standard approach,
preserves all symmetries and therefore satisfies the Ward identities. Our
formulation is equally well defined in the vacuum, one- and few-nucleon sectors
of the theory. The equations (Bethe-Salpeter, Lippmann-Schwinger, etc.) for the
scattering amplitudes of the few-nucleon sector are free of divergences in the
new approach. Unlike the usual cutoff regularization, our 'cutoffs' are
parameters of the Lagrangian and do not have to be removed.Comment: 19 pages, 3 figures, REVTeX 4; version to be published in Phys. Rev.
D, additional section on issues of renormalization in few-body sector
include
The magnetic moment of the \rho-meson
The magnetic moment of the \rho-meson is calculated in the framework of a
low-energy effective field theory of the strong interactions. We find that the
complex-valued strong interaction corrections to the gyromagnetic ratio are
small leading to a value close to the real leading tree level result, g_\rho =
2. This is in a reasonably good agreement with the available lattice QCD
calculations for this quantity.Comment: 10 pages, 4 figure
Complex-mass scheme and resonances in EFT
The complex-mass scheme (CMS) provides a consistent framework for dealing
with unstable particles in quantum field theory and has been successfully
applied to various loop calculations. As applications of the CMS in chiral
effective field theory we consider the form factor of the pion in the time-like
region and the magnetic moment of the Roper resonance.Comment: 4 pages, 2 figures, contribution to the workshop NSTAR 201
Complex-mass renormalization in hadronic EFT: applicability at two-loop order
We discuss the application of the complex-mass scheme to multi-loop diagrams
in hadronic effective field theory by considering as an example a two-loop
self-energy diagram. We show that the renormalized two-loop diagram satisfies
the power counting.Comment: 8 pages, 2 figures, version accepted for publication in EPJ
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