Strong Decays of Excited Heavy Mesons In Chiral Perturbation Theory

We construct an effective Lagrangian describing the interaction of soft pions and kaons with mesons containing a heavy quark and light degrees of freedom in an orbital $p$ wave. The formalism is easily extended to heavy mesons and baryons in arbitrary excited states. We calculate the leading contributions to the strong decays \dtwo\to\d\pi, \dtwo\to\dstar\pi and \done\to\dstar\pi. We confirm the relations between the rates previously obtained by Isgur and Wise using heavy quark symmetry, and find that the absolute widths are consistent with na\"\i ve power counting. We also estimate the branching ratios for the two pion decays \dtwo\to\dstar\pi\pi, \done\to\dstar\pi\pi and \done\to\d\pi\pi, which are dominated by pole graphs. Our predictions depend on the masses and widths of the as yet unseen scalar-pseudovector $p$-wave doublet. Heavy quark spin symmetry predicts \Gamma(\dtwo\to\dstar\pi\pi): \Gamma(\done\to\dstar\pi\pi):\Gamma(\done\to\d\pi\pi)=3:1:2, but this relation is badly violated in practice because $1/M$ effects arising purely from kinematics are large.Comment: (14 pages, 2 figures available from the authors, harvmac.tex required), SLAC-PUB-5812, UCSD/PTH 92-1

Reconclining phi radiative decays with other data for a0(980), fo(980), pi-pi -> KK and pi-pi -> eta-eta

Data for phi -> gamma (eta-pizero) are analysed using the KK loop model and compared with parameters of a0(980) derived from Crystal Barrel data. The eta-pi mass spectrum agrees closely and the absolute normalisation lies just within errors. However, BES parameters for fo(980) predict a normalisation for phi -> gamma (pizero-pizero) at least a factor 2 lower than is observed. This discrepancy may be eliminated by including constructive interference between fo(980) and sigma. The magnitude required for sigma -> KK is consistent with data on pi-pi -> KK. A dispersion relation analysis by Buttiker, Descotes-Genon and Moussallam of pi-pi -> KK leads to a similar conclusion. Data on pi-pi -> eta-eta also require decays of sigma to eta-eta. Four sets of pi-pi -> KK data all require a small but definite fo(1370) signal.Comment: 21 pages, 11 figures, Small rearrangement of reference

Production of eta and 3pi mesons in the pd->3HeX reaction at 1360 and 1450 MeV

The cross sections of the pd -> 3He eta, pd -> 3He pi0 pi0 pi0 and pd -> 3He pi+ pi- pi0 reactions have been measured at beam kinetic energies T_p= 1360 MeV and T_p= 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the differential cross section dsigma/dOmega of the eta meson in the pd -> 3He eta reaction shows a strong forward-backward asymmetry in the CMS. The ratio between the pd -> 3He pi+ pi- pi0 and the pd -> 3He pi0 pi0 pi0 cross sections has been analysed in terms of isospin amplitudes. The reconstructed invariant mass distributions of the pi-pi, 3He-pi and 3He-2pi systems provide hints on the role of nucleon resonances in the 3pi production process.Comment: Shorter version accepted to EPJA 10 pages 14 figure

Model-independent determination of the strong phase difference between D0D^0 and Dˉ0→π+π−π+π−\bar{D}^0 \to\pi^+\pi^-\pi^+\pi^- amplitudes

For the first time, the strong phase difference between $D^0$ and $\bar{D}^0\to\pi^+\pi^-\pi^+\pi^-$ amplitudes is determined in bins of the decay phase space. The measurement uses $818\,\mathrm{pb}^{-1}$ of $e^+e^-$ collision data that is taken at the $\psi(3770)$ resonance and collected by the CLEO-c experiment. The measurement is important for the determination of the $C P$-violating phase $\gamma$ in $B^{\pm}\to D K^{\pm}$ (and similar) decays , where the $D$ meson (which represents a superposition of $D^0$ and $\bar{D}^0$) subsequently decays to $\pi^+\pi^-\pi^+\pi^-$. To obtain optimal sensitivity to $\gamma$, the phase space of the $D \to \pi^+\pi^-\pi^+\pi^-$ decay is divided into bins based on a recent amplitude model of the decay. Although an amplitude model is used to define the bins, the measurements obtained are model-independent. The $CP$-even fraction of the $D \to \pi^+\pi^-\pi^+\pi^-$ decay is determined to be $F_{+}^{4\pi} = 0.769 \pm 0.021 \pm 0.010$, where the uncertainties are statistical and systematic, respectively. Using simulated $B^{\pm}\to D K^{\pm}, D \to \pi^+\pi^-\pi^+\pi^-$ decays, it is estimated that by the end of the current LHC run, the LHCb experiment could determine $\gamma$ from this decay mode with an uncertainty of $(\pm10\pm7)^\circ$, where the first uncertainty is statistical based on estimated LHCb event yields, and the second is due to the uncertainties on the parameters determined in this paper

Production of isoscalar pion pairs in the pd -> 3He pi pi reaction near threshold

The production near threshold of isoscalar pion pairs in the pd -> 3He(pi pi)^0 reaction is estimated in a two-step model which successfully describes the production of eta, omega and eta' mesons. A virtual pion beam, generated through an NN -> d pi reaction on one of the nucleons in the deuteron, produces a second pion via a pi N -> pi pi N reaction on the other nucleon. Using the same scale factor as for heavy meson production, the model reproduces the total pi^0 pi^0 production rate determined at an excess energy of 37 MeV. There are some indications in the data for a suppression of events with low pi pi masses, as in the pi^- p -> pi^0 pi^0 n reaction, and this is confirmed within the model. The model suggests that a significant fraction of the charged pion production in the p d -> 3He pi^+ pi^- reaction at Q=70 MeV might be associated with isoscalar pion pairs, though this does not explain the strong dependence observed on the pi^+ pi^- relative momentum angle.Comment: 13 pages including 4 eps figure

First determination of the CPCP content of D→π+π−π+π−D \to \pi^+\pi^-\pi^+\pi^- and updated determination of the CPCP contents of D→π+π−π0D \to \pi^+\pi^-\pi^0 and D→K+K−π0D \to K^+K^-\pi^0

Quantum-correlated $\psi(3770) \to D\bar{D}$ decays collected by the CLEO-c experiment are used to perform a first measurement of $F_+^{4\pi}$, the fractional $CP$-even content of the self-conjugate decay $D \to \pi^+\pi^-\pi^+\pi^-$, obtaining a value of $0.737 \pm 0.028$. An important input to the measurement comes from the use of $D \to K^0_{\rm S}\pi^+\pi^-$ and $D \to K^0_{\rm L}\pi^+\pi^-$ decays to tag the signal mode. This same technique is applied to the channels $D \to\pi^+\pi^-\pi^0$ and $D \to K^+K^-\pi^0$, yielding $F_+^{\pi\pi\pi^0} = 1.014 \pm 0.045 \pm 0.022$ and $F_+^{KK\pi^0} = 0.734 \pm 0.106 \pm 0.054$, where the first uncertainty is statistical and the second systematic. These measurements are consistent with those of an earlier analysis, based on $CP$-eigenstate tags, and can be combined to give values of $F_+^{\pi\pi\pi^0} = 0.973 \pm 0.017$ and $F_+^{KK\pi^0} = 0.732 \pm 0.055$. The results will enable the three modes to be included in a model-independent manner in measurements of the unitarity triangle angle $\gamma$ using $B^\mp \to DK^\mp$ decays, and in time-dependent studies of $CP$ violation and mixing in the $D\bar{D}$ system.Comment: Minor revisions following journal acceptanc