96 research outputs found

### Strong and Weak Interactions in B to pi+ pi- K Decays

To describe the weak three-body B decays into pi+ pi- K, we recently derived
amplitudes based on two-body QCD factorization followed by pi+ pi- final state
interactions in isoscalar S- and isovector P-waves. We study here the
sensitivity of the results to the values of the B to f0(980) transition form
factor and to the effective decay constant of the f0(980).Comment: Contribution to the Few Body 18 conference in Santos, Brazil, August
21-26, 2006, 5 pages, to be published in Nuclear Physics

### Lorentz contraction, geometry and range in antiproton-proton annihilation into two pions

We present a geometric interpretation of the so-called annihilation range in
reactions of the type $\bar pp \to$ {\em two light mesons} based upon Lorentz
effects in the highly relativistic final states
($\gamma=E_{\mathrm{cm}}/2mc^2\simeq 6.8-8.0$). Lorentz-boosted meson wave
functions, within the framework of the constituent quark model, result in a
richer angular dependence of the annihilation amplitudes and thus in higher
partial wave contributions ($J>1$) than usually obtained. This approach sheds
some light on what could be a "{\em short}" annihilation range and how it is
influenced by the angular distribution of the final states.Comment: LEAP05 (Bonn/Juelich) proceedings, 5 page

### Resonances and weak interactions in $D^+ \to\pi^+ \pi^- \pi^+$ decays

We describe the $\pi\pi$ $S$-wave in $D^+ \to\pi^+ \pi^- \pi^+$ decays using
a unitary model for the $\pi\pi$ Final State Interactions (FSI). The three body
decay is treated as a quasi two-body process where, at the weak vertex, the D
meson decays into a resonance and a pion. The weak part of the decay amplitude
is evaluated using the effective weak Hamiltonian within the factorization
approximation.Comment: 4 pages. Contribution to the X Hadron Physics, Florianopolis-Brazil,
March 26-31, 200

### On the structure of the X(1835) baryonium

The measurement by the BES collaboration of J/psi -> gamma p pbar decays
indicates an enhancement at the p-pbar threshold. In another experiment BES
finds a peak in the invariant mass of pi-mesons produced in the possibly
related decay J/psi -> gamma pi+ pi- eta'. Using a semi-phenomenological
potential model which describes all the N-Nbar scattering data, we show that
the explanation of both effects may be given by a broad quasi-bound state in
the spin and isospin singlet S wave. The structure of the observed peak is due
to an interference of this quasi-bound state with a background amplitude and
depends on the annihilation mechanism.Comment: 7 pages, 7 figures, this version corresponds to the published paper
in Phys. Rev. C: minor corrections done and in section 5 suggestions of
experiments to confirm the link of the X(1835) to the antiproton-proton
syste

### Relativistic effects and angular dependence in the reaction antiproton-proton -> pi^- pi^+

We present a new fit to the LEAR data on antiproton-proton -> pi^- pi^+
differential cross sections and analyzing powers motivated by relativistic
considerations. Within a quark model describing this annihilation we argue,
since the pions are highly energetic, that relativistic effects cannot be
neglected. The intrinsic pion wave functions are Lorentz transformed to the
center of mass frame. This change in quark geometry gives rise to additional
angular dependence in the transition operators and results in a relative
enhancement of higher J \ge 2 partial wave amplitudes. The fit to the data is
improved significantly.Comment: Revtex 4, 7 pages, 5 figures. Continuation and results of a previous
paper: nucl-th/040305

### A combined study of the pion's static properties and form factors

We study consistently the pion's static observables and the elastic and
\gamma*\gamma -> \pi^0 transition form factors within a light-front model.
Consistency requires that all calculations are performed within a given model
with the same and single adjusted length or mass-scale parameter of the
associated pion bound-state wave function. Our results agree well with all
extent data including recent Belle data on the \gamma*\gamma -> \pi^0 form
factor at large q^2, yet the BaBar data on this transition form factor resists
a sensible comparison. We relax the initial constraint on the bound-state wave
function and show the BaBar data can partially be accommodated. This, however,
comes at the cost of a hard elastic form factor not in agreement with
experiment. Moreover, the pion charge radius is about 40% smaller than its
experimentally determined value. It is argued that a decreasing charge radius
produces an ever harder form factor with a bound-state amplitude difficultly
reconcilable with soft QCD. We also discuss why vector dominance type models
for the photon-quark vertex, based on analyticity and crossing symmetry, are
unlikely to reproduce the litigious transition form factor data.Comment: 14 pages, 7 figures, 2 Tables; minor changes; 2 new references added
(Ref. 54 and 57); version to be published in Few Body Physic

### Towards a unitary Dalitz plot analysis of three-body hadronic B decays

A unitary model of the final state kaon pion interaction amplitudes in the B
--> K pi pi decays is constructed. The weak decay penguin amplitudes, derived
in QCD factorization, are supplemented by phenomenological contributions. The
strange kaon- pion scalar and vector form factors are used to calculate the
kaon pion effective mass and helicity angle distributions, branching ratios, CP
asymmetries and the phase difference between the B0 and anti B0 decay
amplitudes to K*(892) pi. The fit on the phenomenological parameters leads to a
good agreement with the experimental data, particularly for the
B --> K*(892) pi decays. However, our predicted B+- --> K*0(1430) pi+-,
K*0(1430)--> K+-pi-+ branching fraction is smaller than the results of the
Belle and BaBar collaborations, obtained from isobar model analyses. A new
parameterization of the S-wave kaon- pion effective mass distribution, which
can be used in future experimental Dalitz plot analyses, is proposed.Comment: 5 pages, 1 figure, contribution to Proc. Int. Europhysics Conference
on High Energy Physics (HEP2009), July 16-22, 2009, Krakow, Poland,
PoS(HEP2009)20

### Final state interactions and CP violation in B decays to three pseudoscalars

We study CP violation and final state interactions between pions and kaons in
B+, B-, B0 and bar B0 decays into K pi pi. The weak transition amplitudes
consist of two terms: the first part is derived in QCD factorization approach
and the second one is a phenomenological long-distance charming penguin
contribution. The final state K pi interactions in S- and P-waves are described
by strange scalar and vector form factors, respectively. These are determined
using a unitary coupled channel model together with chiral symmetry and
asymptotic QCD constraints. The final state interactions are dominated by
presence of the scalar K*0(1430) and the vector K*(892) resonances. We show
that additional charming penguin amplitudes are needed to reproduce the latest
experimental K pi effective mass and helicity angle distributions, branching
fractions and asymmetries obtained by Belle and BaBar collaborations.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Nov. 29 - Dec. 4 2009, Florida State Universit

### Pseudoscalar-scalar transition form factors in covariant light front dynamics

In an explicitly covariant light-front formalism, we analyze transition form
factors between pseudoscalar and scalar mesons. Application is performed in
case of the $B \to f_0(980)$ transition in the full available transfer momentum
range $q^2$.Comment: 4 pages, 4 figures. Talk given at the XXXIII International Conference
on High Energy Physics, ICHEP06, Moscow, 26 July-02 Augus

### A relativistic treatment of pion wave functions in the annihilation antiproton-proton -> pi^-pi^+

Quark model intrinsic wave functions of highly energetic pions in the
reaction \bar pp->\pi^-\pi^+ are subjected to a relativistic treatment. The
annihilation is described in a constituent quark model with A2 and R2
flavor-flux topology and the annihilated quark-antiquark pairs are in 3P_0 and
3S_1 states. We study the effects of pure Lorentz transformations on the
antiquark and quark spatial wave functions and their respective spinors in the
pion. The modified quark geometry of the pion has considerable impact on the
angular dependence of the annihilation mechanisms.Comment: 10 pages in revtex format, 3 figure

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