1,970 research outputs found
Dispersive representation of the K pi vector form factor and fits to tau -> K pi nu(tau) and Ke3 data
Recently, we introduced several dispersive representations for the vector
form factor and fitted them to the Belle spectrum of . Here, we briefly present the model and discuss the results for the
slope and curvature of arising from the best fit. Furthermore, we
compare the pole position of the charged computed from our model
with other results in the literature. Finally, we discuss the prospects of a
simultaneous fit to and spectra.Comment: Talk given at "International Workshop on Effective Field Theories:
from the pion to the upsilon", February 2009, Valencia, Spain. 7 pages, 2
figures. PoS style. Minor correction in figure
Central pseudoscalar production in pp scattering and the gluon contribution to the proton spin
Central pseudoscalar production in scattering is suppressed at small
values of , where is defined as the difference between the momenta
transferred from the two protons. Such a behaviour is expected if the
production occurs through the fusion of two vectors. Photon exchange could
provide the dominant contribution at low transferred momenta, but we argue that
an extension of the experiment could probe the gluon contribution to the proton
spin.Comment: 12 pages, 2 figures and 3 tables, uses epsf.sty. Added references and
tables. Minor changes include
The eta transition form factor from space- and time-like experimental data
The transition form factor is analysed for the first time in both
space- and time-like regions at low and intermediate energies in a
model-independent approach through the use of rational approximants. The
experimental data provided by the A2
Collaboration in the very low energy region of the dilelectron invariant mass
distribution allows for the extraction of the most precise up-to-date slope and
curvature parameters of the form factors as well as their values at zero and
infinity. The impact of these new results on the mixing parameters of the
- system, together with the role played by renormalisation
dependent effects, and on the determination of the couplings from
and radiative decays are also discussed.Comment: 16 pages, 17 figures; v2: additional comments, references added;
mathces published version in EPJ
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