Phase Motion of the Scalar ππ\pi \pi Amplitudes in D+D^+, Ds+→π−π+π+D^+_s \to \pi^-\pi^+\pi^+ Decays

We make a direct and model-independent measurement of the low $\pi^+\pi^-$ mass phase motion in the $D^+ \to \pi^-\pi^+\pi^+$ decay. Our preliminary results show a strong phase variation, compatible with the isoscalar $\sigma(500)$ meson. This result confirms our previous result where we found evidence for the existence of this scalar particle using full Dalitz-plot analysis. We apply the Amplitude Difference (AD) method to the same Fermilab E791 data sample used in the preceding analysis. We also give an example of how we extract the phase motion of the scalar amplitude, looking at the $f_0(980)$ in $D^+_s \to \pi^-\pi^+\pi^+$ decay.Comment: Invited talk given at Scalar Meson Workshop, SUNY Institute of Technology, May 2003, Utica, NY. 14 pages, 13 figure

Charmless B decays in modes with similar tree and penguin contributions

Charmless $B$ decays are dominated by contributions from the short distance amplitudes from tree level and penguin loop-level amplitudes. The Tree contribution presents a weak phase $\gamma$. The relationship between these two amplitudes can generated a CP asymmetry depending from the relative amount among them in a particular decay. In multi-body charmless $B$ decays, these relative contribution can change along the phase space, given a non isotropic distribution of CP asymmetries in the Dalitz plot. Two recent LHCb analyses involving charmless multi-body B decays are discussed: the obsevation of CP asymmetries in the phase space of the three-body decays $B^\pm \to \pi^\pm \pi^+ \pi^-$ and $B^\pm \to \pi^\pm K^+ K^-$; and the angular analysis of the $B^0 \to \phi K^*(892)^0$ decay.Comment: Proceedings to FPCP-2014- Flavor Physics \& CP Violation, Marseille, France, May 25-30, 201

Light Scalar Mesons σ(500)\sigma(500), f0(980)f_0(980) and κ\kappa in Charm Meson Decays

We present recent results on scalar light mesons based on Dalitz plot analyses of charm decays from Fermilab experiment E791. Scalar mesons are found to have large contributions to the decays studied, $D^+\to K^-\pi^+\pi^+$ and $D^+, D_s^+\to\pi^-\pi^+\pi^+$. From the first decay, we find good evidence for the existence of the light and broad $\kappa$ meson and we measure its mass and width. We find strong evidence for the $\sigma(500)$ meson from $D^+\to\pi^-\pi^+\pi^+$ decay and measure its mass and width. We also present the results obtained for the $f_0(980)$ parameters through the $D^+_s \to\pi^-\pi^+\pi^+$ decay. These results demonstrate the importance of charm decays as a new environment for the study of light meson physics.Comment: 10 pages, 2 figures. To appear in proceedings of VIII International Workshop on Hadron Physics 2002 Rio Grande do Sul, Brazil. World Scientific editio

Charm rescattering contribution in rare Bc+→K+K−π+B^+_c \to K^+ K^- \pi^+ decay

Following the experimental results from LHCb on the rare decay $B^+_c \to K^-K^+\pi^+$, we investigate the possibility where this process is dominated by a double charm rescattering. The $B_c$ decay to double charm channels have a weak topology that is favoured in comparison with the direct production of $K^-K^+\pi^+$ in the final state, suppressed by quark annihilation. The decay amplitude for $B^+_c \to K^-K^+\pi^+$ with $B_c$ decaying first to double charm channels is described by a charm penguin diagram, represented by charm hadronic triangle loops, which reach the final state of interest after $D\bar{D}\to K\bar{K}$ or $D^+ D^-_s \to \pi^+ K^-$ transitions. We show that these processes give rise to non-resonant amplitudes with a clear signature in the Dalitz plot. In a near future, the new data from LHCb run II will be able to confirme if the main hypotheses of this work is correct and the dominant mechanism to produce $K^+K^+\pi^-$ from the decay of $B^+_c$ is through charm rescattering

Dalitz plot analysis and branching fraction measurement of D+ and Ds+ -> pi+pi-pi+

Fermilab fixed target experiment E791 obtained a sample of $1172 \pm 61$ events of $D^+ \to \pi^- \pi^+ \pi^+$ and 848 $\pm 44$ events of $D_s^+ \to \pi^- \pi^+ \pi^+$ decays. We find respectively $B (D^+ \to \pi^- \pi^+ \pi^+) / B (D^+ \to K^- \pi^+ \pi^+) = 0.0311 \pm 0.0018 ^ {+0.0016}_{-0.0026}$ and $B(D_s^+ \to \pi^+ \pi^- \pi^+) / B(D_s^+ \to \phi \pi^+) = 0.245 \pm 0.028^{+0.019}_{-0.012}$. Using a coherent amplitude analysis to fit the Dalitz plot of the $D^+ \to \pi^- \pi^+ \pi^+$ decay, we find strong evidence for a scalar resonance of mass $478^{+24}_{-23} \pm 17$MeV/$c^2$ and width $324^{+42}_{-40} \pm 21$ MeV/$c^2$, compatible with what is expected for the isoscalar meson $\sigma$ >. The $D^+ \to \sigma(500) \pi^+$ fraction accounts for approximately half of all three-charged-pion decays of the $D^+$ . From the Dalitz plot analysis of the $D_s^+ \to \pi^- \pi^+ \pi^+$ decay events, we find significant contributions from the channels $\rho^0(770)\pi^+$, $\rho^0(1450)\pi^+$, $f_0(980)\pi^+$, $f_2(1270)\pi^+$, and $f_0(1370)\pi^+$. We also present new measurement of the masses and widths of the isoscalar resonances $f_0(980)$ and $f_0(1370)$.Comment: 4 pages, 4 figures, talk presented in BEACH2000, Valencia, Spai