1,761 research outputs found
Lowest Order Effective Field Theory for the weak interaction
The interaction, responsible for the decay of
hypernuclei, is studied by means of an Effective Field Theory where the long
range physics is described by pion and kaon exchange mechanisms, and its short
range counterpart is obtained from the most general non-derivative local
four-fermion interaction. We show that, including the Lowest Order Parity
Conserving contact terms, allows us to reproduce the total decay rates for
, and with
a reasonable value of , while in order to get a prediction for
the Parity Violating (PV) asymmetry compatible with experiments, we have to
include the Lowest Order PV contact pieces.Comment: 3 pages, no figures. Contribution to the 17th International IUPAP
Conference on Few-body Problems in Physics, June 5-10, 2003 Durham, North
Carolina, USA. Uses espcrc1.st
Neutrino Physics
The basic concepts of neutrino physics are presented at a level appropriate
for integration into elementary courses on quantum mechanics and/or modern
physics.Comment: Prepared for the American Journal of Physics; 50 pages; 11 figures
(10 included); late
Hadronic parity violation and effective field theory
The subject of hadronic parity violation is briefly reviewed and an approach based on effective field theory is advocated in order to resolve current problems
The role of resonances in non-leptonic hyperon decays
We examine the importance of resonances for the non-leptonic hyperon decays
in the framework of chiral perturbation theory. Lower lying resonances are
included into the effective theory. Integrating out the heavy degrees of
freedom in the resonance saturation scheme generates higher order counterterms
in the effective Lagrangian, providing an estimate of the pertinent coupling
constants. A fit to the eight independent decay amplitudes that are not related
by isospin symmetry is performed and reasonable agreement for both s- and p-
waves is achieved.Comment: 16 pages, 2 figure
Non-leptonic hyperon decays in chiral perturbation theory
The non-leptonic hyperon decays are analyzed up to one-loop order including
all counterterms in the framework of heavy baryon chiral perturbation theory.
We use the exchange of the spin-3/2 decuplet resonances as an indication of
which low-energy constants contribute significantly to these investigated
processes . We choose four independent decay amplitudes that are not related by
isospin relations in order to perform a fit for the pertinent low-energy
constants and find a satisfactory fit both for s- and p-waves. The chiral
corrections to the lowest order forms for the s-waves are moderate whereas
there are significant modifications of the p-wave amplitudes.Comment: 40 pages, 4 figure
Extracting Electric Polarizabilities from Lattice QCD
Charged and neutral, pion and kaon electric polarizabilities are extracted
from lattice QCD using an ensemble of anisotropic gauge configurations with
dynamical clover fermions. We utilize classical background fields to access the
polarizabilities from two-point correlation functions. Uniform background
fields are achieved by quantizing the electric field strength with the proper
treatment of boundary flux. These external fields, however, are implemented
only in the valence quark sector. A novel method to extract charge particle
polarizabilities is successfully demonstrated for the first time.Comment: 17 pages, 6 figures, a few clarifications added, published versio
Subleading corrections to parity-violating pion photoproduction
We compute the photon asymmetry Bγ for near threshold parity-violating (PV) pion photoproduction through subleading order. We show that subleading contributions involve a new combination of PV couplings not included in previous analyses of hadronic PV. We argue that existing constraints on the leading order contribution to Bγ—obtained from the PV γ-decay of 18F—suggest that the impact of the subleading contributions may be more significant than expected from naturalness arguments
Chiral Symmetry and the Parity-Violating Yukawa Coupling
We construct the complete SU(2) parity-violating (PV)
interaction Lagrangian with one derivative, and calculate the chiral
corrections to the PV Yukawa coupling constant through in the leading order of heavy baryon expansion. We
discuss the relationship between the renormalized \hpi, the measured value of
\hpi, and the corresponding quantity calculated microscopically from the
Standard Model four-quark PV interaction.Comment: RevTex, 26 pages + 5 PS figure
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