20 research outputs found
Chiral Symmetry and Charmonium Decays to Two Pseudoscalars
We apply hard pion Chiral Perturbation Theory to charmonium decays to
, and . We first discuss why we expect to be able to
provide results for the chiral logarithms in and decays
to two pseudoscalars while for the decays from , and
no simple prediction is possible. The leading chiral logarithm
turns out to be absent for . This result is true for
all fully chiral singlet states of spin zero and two.Comment: 7 page
Determination of Low Energy Constants and testing Chiral Perturbation Theory at Next to Next to Leading Order
We present the results of a search for relations between observables that are
independent of the Chiral Pertubation Theory (ChPT) Next-to-Next-to-Leading
Order (NNLO) Low-Energy Constants (LECs). We have found some relations between
observables in , scattering and decay which have been
evaluated numerically using the old fit (fit 10 in [1] of the NLO LECs.Comment: 7 page
Determination of Low Energy Constants and testing Chiral Perturbation Theory at order (NNLO)
We present the results of a search for relations between observables that are
independent of the Chiral Perturbation Theory (ChPT) Next-to-Next-to-Leading
Order (NNLO) Low-Energy Constants (LECs). We have found some relations between
observables in , scattering and decay which have been
evaluated numerically using fit 10 in \cite{Amoros:2001cp} for the NLO LECs. We
also show some preliminary results for a new global fit of the NLO LECsComment: 9 page
Hard Pion Chiral Perturbation Theory for and Formfactors
We use one-loop Heavy Meson Chiral Perturbation Theory (HMCHPT) as well as a
relativistic formulation to calculate the chiral logarithms
contributing to the formfactors of
the semileptonic decays at momentum transfer away from
. We give arguments why this chiral behavior is
reliable even in the energy regime with hard or fast pions. These results can
be used to extrapolate the formfactors calculated on the lattice to lower light
meson masses.Comment: 16 pages, two wrong statements about relation relativistic-heavy
meson formfactors changed and (a lot of) misprints corrected. These include
misprints in the main result
A new global fit of the at next-to-next-to-leading order in Chiral Perturbation Theory
A new fit is done to obtain numerical values for the order
low-energy-constants in Chiral Perturbation Theory. This includes both
new data and new calculated observables. We take into account masses, decay
constants, , and scattering lengths and slopes and
the slope of the pion scalar formfactor. We compare in detail where the changes
w.r.t. to the 10 year old "fit 10" come from. We discuss several scenarios for
estimating the order constants and search for possible values of
them that provide a good convergence for the ChPT series. We present two such
sets. One big change is that the fits do not have the expected behaviour in the
limit of large as well as before.Comment: 41 pages, p^4 values of the l_i added, numerical values for f_+(0) in
Kl3 added, a comparison with the LECS from Ecker et al., Phys. Lett. B692
(2010) 184 [arXiv:1004.3422 [hep-ph]] adde
Relations at Order in Chiral Perturbation Theory
We report on a search of relations valid at order in Chiral
Perturbation Theory. We have found relations between ,
scattering, decays, masses and decay constants and scalar and
vector form factors. In this paper we give the relations and a first numerical
check of them.Comment: 18 pages, numerical discussion extended including a new figur