1,361 research outputs found
Hints on the quadrupole deformation of the (1232)
The E2/M1 ratio (EMR) of the (1232) is extracted from the world data
in pion photoproduction by means of an Effective Lagrangian Approach (ELA).This
quantity has been derived within a crossing symmetric, gauge invariant, and
chiral symmetric Lagrangian model which also contains a consistent modern
treatment of the (1232) resonance. The \textit{bare} s-channel
(1232) contribution is well isolated and Final State Interactions (FSI)
are effectively taken into account fulfilling Watson's theorem. The obtained
EMR value, EMR%, is in good agreement with the latest lattice
QCD calculations [Phys. Rev. Lett. 94, 021601 (2005)] and disagrees with
results of current quark model calculations.Comment: Enlarged conclusions and explanations on the E2/M1 ratio. Figure 3
improved. References updated. 5 pages. 3 figures. 2 tables. Accepted for
publication in Physical Review
On the Determination of and from Hadronic Two Body Decays
{}From Class I decays : B^o \ra \pi^+ ( \rho^+ ) + D^- ( {D^*}^- ), we
determine , and from Class III decays : B^+ \ra \pi^+ ( \rho^+ ) +
\ol{D}^o ( {\ol{D}^*}^o ), we determine an allowed domain in the plane. We find that within one standard deviation errors, the allowed band
of from Class I decays is at least three standard deviations removed from
the allowed domain from Class III decays.If we expand the
experimental errors to two standard deviations we do find a small intersection
between the band and the allowed domain. The results
usually quoted in the literature lie in this intersection. We suggest : (1) an
independent measurement of the branching ratio for the Class III decay, B^+
\ra \rho^+ \ol{D}^o , (2) a high-statistics measurement of the branching ratio
of the Class I decay, B \ra \ol{D} ( \ol{D}^* ) + D_s ( D_s^* ) in both
charged states, and (3) a measurement of the longitudinal polarization fraction
in the Class III decay B^+ \ra \rho^+ {\ol{D}^*}^o to shed more light on the
questions involved .Comment: 9pages(Latex)+4 figures(PS file appended), PAR/LPTHE/94-2
B ->\eta_c K(\eta_c^\prime K) decays in QCD factorization
We study the exclusive decays of meson into pseudoscalar charmonium
states and within the QCD factorization approach and
find that the nonfactorizable corrections to naive factorization are infrared
safe at leading-twist order. The spectator interactions arising from the kaon
twist-3 effects are formally power-suppressed but chirally and logarithmically
enhanced. The theoretical decay rates are too small to accommodate the
experimental data. On the other hand, we compare the theoretical calculations
for , and , and find that the
predicted relative decay rates of these four states are approximately
compatible with experimental data.Comment: 8 pages, LaTex, 1 figure, one footnote and two references adde
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