Precision determination of the pi-N scattering lengths and the charged pi-NN coupling constant

We critically evaluate the isovector GMO sumrule for the charged $\pi N N$ coupling constant using recent precision data from $\pi ^-$p and $\pi^-$d atoms and with careful attention to systematic errors. From the $\pi ^-$d scattering length we deduce the pion-proton scattering lengths ${1/2}(a_{\pi ^-p}+a_{\pi ^-n})=(-20\pm 6$(statistic)$\pm 10$ (systematic))~$\cdot 10^{-4}m_{\pi_c}^{-1}$ and ${1/2}(a_{\pi ^-p}-a_{\pi ^-n})=(903 \pm 14)\cdot 10^{-4}m_{\pi_c}^{-1}$. From this a direct evaluation gives $g^2_c(GMO)/4\pi =14.20\pm 0.07$(statistic)$\pm 0.13$(systematic) or $f^2_c/4\pi= 0.0786\pm 0.0008$.Comment: 4 pages, 1 figure, latex and postscript; invited talk at PANIC99; to appear in Nucl. Phys. A; changed notation: g^2 and f^2 replaced by conventional g^2/4\pi and f^2/4\p

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

Form factors in B->f0(980) and D->f0(980) transitions from dispersion relations

Within the dispersion relation approach we give the double spectral representation for space-like and time-like B-> f_0(980) and D-> f_0(980) transition form factors in the full q^2 range. The spectral densities, being the input of the dispersion relations, are obtained from a triangle diagram in the relativistic quark model.Comment: Talk given at MESON 2006, Krakow, 9-13 June 200

CP violation and final state interactions in B --> K pi pi decays

Effects of CP violation and of final state interactions between pairs of pseudoscalar mesons are studied in three-body B+, B-, B0 and antiB0 decays into K pi pi. An alternative approach to the isobar model for three-body B decays is proposed. It is based on the QCD factorization approximation and the knowledge of the meson-meson form factors. Some phenomenological charming penguin amplitudes are needed to describe the branching fractions, direct CP asymmetries of the quasi-two-body B --> K*(892) pi and B --> K0*(1430) pi decays as well as the K pi effective mass and the helicity angle distributions. The experimental branching fractions for the B --> K0*(1430) pi decay, obtained by the Belle and BaBar collaborations using the isobar model, are larger than our predictions by about 52 per cent.Comment: 3 pages, contribution to International Europhysics Conference on High Energy Physics HEP 2007, Manchester (England), July 19-25, 200

New Extended and Quantified Constraints in XML Schema

Date du colloque : 01/2009International audienc

Scalar resonances in a unitary π−π\pi-\pi SS-wave model for D+→π+π−π+D^+ \to \pi^+ \pi^- \pi^+

We propose a model for $D^+ \to \pi^+ \pi^- \pi^+$ decays following experimental results which indicate that the two-pion interaction in the $S$-wave is dominated by the scalar resonances $f_0(600)/\sigma$ and $f_0(980)$. The weak decay amplitude for $D^+\to R \pi^+$, where $R$ is a resonance that subsequently decays into $\pi^+\pi^-$, is constructed in a factorization approach. In the $S$-wave, we implement the strong decay $R\to \pi^-\pi^+$ by means of a scalar form factor. This provides a unitary description of the pion-pion interaction in the entire kinematically allowed mass range $m_{\pi\pi}^2$ from threshold to about 3 GeV$^2$. In order to reproduce the experimental Dalitz plot for \Dppp, we include contributions beyond the $S$-wave. For the $P$-wave, dominated by the $\rho(770)^0$, we use a Breit-Wigner description. Higher waves are accounted for by using the usual isobar prescription for the $f_2(1270)$ and $\rho(1450)^0$. The major achievement is a good reproduction of the experimental $m_{\pi\pi}^2$ distribution, and of the partial as well as the total \Dppp branching ratios. Our values are generally smaller than the experimental ones. We discuss this shortcoming and, as a byproduct, we predict a value for the poorly known $D\to \sigma$ transition form factor at $q^2=m_\pi^2$.Comment: 23 pages, 2 figures. Two new equations. The value for the strength of the contribution of the scalar form factor now agrees with other results in the literature. Main results unchanged. Version to appear in Phys. Rev.