Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSM

We study the nine possible rare charm meson decays D->Pl^+l^- (P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with the branching ratio 1*10^(-6) is expected to have the best chances for an early experimental discovery. The short distance contribution in the five Cabibbo suppressed channels arises via the c->ul^+l^- transition; we find that this contribution is detectable only in the D->pi l^+l^- decay, where it dominates the differential spectrum at high-q^2. The general Minimal Supersymmetric Standard Model can enhance the c->ul^+l^- rate by up to an order of magnitude; its effect on the D->Pl^+l^- rates is small since the c->ul^+l^- enhancement is sizable in low-q^2 region, which is inhibited in the hadronic decay.Comment: 17 page

Study of the process e+e−→π+π−π0e^+e^- \to \pi^+\pi^-\pi^0 in the energy region s\sqrt[]{s} from 0.98 to 1.38 GeV.}

The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $\sqrt[]{s} = 980 \div 1380$ MeV. The measured cross section, together with the $e^+e^-\to \pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $\omega$, $\phi$ mesons and two $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions, with masses $m_{\omega^\prime}\sim 1490$,$m_{\omega^{\prime\prime}}\sim 1790$ MeV and widths $\Gamma_{\omega^\prime}\sim 1210$, $\Gamma_{\omega^{\prime\prime}}\sim 560$ MeV. The analysis of the $\pi^+\pi^-$ invariant mass spectra in the energy region $\sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-\to\omega\pi^0\to\pi^+\pi^-\pi^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-\to\omega\pi$ and $e^+e^-\to\rho\pi$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.Comment: 29 pages REVTEX and 17 figures, accepted for publication in Physical Review

Infra-red, Raman and p.m.r. spectra of trimethyltriammineplatinum(IV) chloride

The infra-red spectra of solid [Pt(CH 3) 3(NH 3) 3]Cl and [Pt(CH 3) 3(ND 3) 3]Cl between 4000 and 300 cm -1 the Raman spectra of the compounds in H 2O and D 2O have been obtained. Vibrational assignments have been made on the basis of C 3v symmetry for the complex ion. In the Raman spectrum of the light compound, lines at 584 and 390 cm -1 were assigned to PtC and PtN stretching vibrations respectively. In the N-deuterated compound the corresponding frequencies were 585 and 364 cm -1. The infra-red spectra of the solid compounds included bands at 581, 410 and 377 cm -1 (light) and 585, 381 and 352 cm -1 (N-deuterated) which were attributed to skeletal stretching vibrations. From the p.m.r. spectrum J 195PtCH3 was found to be 71 c/s. The Raman spectra and solution behaviour of Pt[(CH 3) 3(NH 3) 3] + and [Pt(NH 3) 6] 4+ were compared

1H NMR spectra and characterization of some trimethylplatinum(IV) compounds. Evidence for cis and trans influences

1H NMR spectra of complexes of the types Pt(CH3)3L2X (L2 = 2,2′-bipyridine, bis(pyridine), or bis(3,5-lutidine), and X = uninegative unidentate ligand); [Pt(CH3)3BipyX]ClO4 (X = neutral unidentate ligand), and Pt(CH3)3LI (L = substituted 2,2′-pipyridine or 1,10-phenanthroline) have been recorded. The magnitude of J(195PtCH) for the methyl group trans to X has been found to be markedly dependent on X, with values ranging from 40.5 to 82.0 Hz. Much smaller variations occur in J(195PtCH) for the methyl groups trans to the heterocyclic ligands as X is varied ( CN > PPh3 > NO2 > amines ∼ Py ∼ SCN > NCO ∼ NCS ∼ I > Br ∼ Cl >/ CH3COO > NO3 > H2O. Infrared data for the vibrations of X, where X = polyatomic uninegative ligand, and for the methyl vibrations have also been recorded

Pentacoordinate silicon complexes with dynamic motion resembling a pendulum on the SN2 reaction pathway

A series of glutarimide derivatives which has two carbonyl coordination sites for intramolecular pentacoordination at silicon with a X1+nSiC3-nO moiety have been synthesised and characterized. The substituent (leaving group) effects on the Si-O bond exchange between the two coordination sites (resembling a pendulum) have been studied by comparison of the differently substituted (X = F, Cl, OTf, Br and I) structures. The activation parameters for the Si-O bond exchange process were measured by NMR and separately computed and are consistent with the strength of Si-O bond coordination and the nature of the leaving group, X. The temperature-dependent Si-29 NMR spectroscopy is supported by X-ray crystallography and shows that the tetrahedral reactant is converted into pentacoordinate intermediates by intramolecular O-Si association followed by reversion to a tetrahedral geometry by Si-X dissociation. The two association/dissociation patterns offer a model for nucleophilic substitution at a silicon atom. A continuum of structures on the S(N)2 reaction profile from the glutarimide derivatives correlates reasonably well with the structural data obtained from derivatives of lactams, diketopiperazines and quinolones