2,039 research outputs found
Vector Meson Masses in Chiral Perturbation Theory
We discuss the vector meson masses within the context of Chiral Perturbation
Theory performing an expansion in terms of the momenta, quark masses and 1/Nc.
We extend the previous analysis to include isospin breaking effects and also
include up to order . We discuss vector meson chiral perturbation theory
in some detail and present a derivation from a relativistic lagrangian. The
unknown coefficients are estimated in various ways. We also discuss the
relevance of electromagnetic corrections and the implications of the present
calculation for the determination of quark masses.Comment: 17 pages, LaTeX, 2 figures. Revised version to appear in Nuclear
Physics B. One reference added, some misprints, mainly in the appendix,
correcte
The Vector and Scalar Form Factors of the Pion to Two Loops
We calculate the vector and scalar form factors of the pion to two loops in
Chiral Perturbation Theory. We estimate the unknown O(p^6) constants using
resonance exchange. We make a careful comparison to the available data and
determine two O(p^4) constants rather precisely, and two O(p^6) constants less
precisely. We also use Chiral Perturbation Theory to two loops to extract in a
model--independent manner the charge radius of the pion from the available
data, and obtain \rpiV=0.437\pm 0.016 fm^2.Comment: Latex2e, JHEP.cls, 30 pages 5 figure
Matching the Heavy Vector Meson Theory
We show how to obtain a ``heavy'' meson effective lagrangian for the case
where the number of heavy particles is not conserved. We apply the method in a
simple example at tree level and perform then the reduction for the case of
vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant
fashion. Some examples showing that ``heavy'' meson effective theory also works
at the one-loop level are included.Comment: 11 pages, 2 figures, revte
Low Energy Constants from Kl4 Form-Factors
We have calculated the form-factors F and G in K ---> pi pi e nu decays (Kl4)
to two-loop order in Chiral Perturbation Theory (ChPT). Combining this together
with earlier two-loop calculations an updated set of values for the L's, the
ChPT constants at p^4, is obtained. We discuss the uncertainties in the
determination and the changes compared to previous estimates.Comment: 6 pages, uses axodraw.sty, 2 figures, bug in program corrected, new
numerical result
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