Charm hadronic decays and quantum correlations at CLEO-c

Several recent CLEO-c results on hadronic decays of charm mesons are reviewed.Topics include measurements of precision branching fractions for exclusive modes,investigations of inclusive rates,and analyses of Dalitz plots.In addition,the quantum correlations of the D pairs produced at the ψ(3770) are exploited to measure phase information that is of current interest for both D and B physics.     

Détermination des Axes Propres et des Valeurs Principales du Tenseur ḡ dans deux Radicaux Libres Nitroxydes par Étude de Monocristaux

The low temperature phase structure of the nitroxide radical 2,2,6,6-tetramethyl piperidin-1-oxyl (Tanane) is isomorphic of 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl (Tanol). An ESR study of single crystals yielded the principal values and position of principal axes of the ? tensor in these two radicals. The major significant differences observed in Tanol are a moderate decrease in the g_xx, g_yy and g_zz values, and a deviation of the principal axes situated in the molecular mirror plane from the N? O bond and π-orbital, respectively (8° ± 2°). The intermolecular hydrogen bond is probably responsible for this fact.     

A limit on the lepton-family number violating process π → μe

A FNAL E799 Collaboration has carried out a search for the lepton-family number violating decay π⁰ → μ^±e using π⁰'s produced from K_L → π⁰π⁰π⁰ decays in flight. No events were observed. Assuming that lepton-family number violation is charge independent, the 90% confidence level upper limit on

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was determined to be 8.6 × 10⁻⁹.     

Nitroxydes 91 : β-Cétoénolates nitroxydes

β-Ketoaldehyde derivatives of simple piperidine and pyrrolidine nitroxides as spin labelled ligands give paramagnetic three-electron copper complexes.     

Nitroxydes-LXVIII : Synthese et etude cinetique de la decomposition du t-butyl isopropyl nitroxyde. Effet isotopique

Decomposition of t-butyl isopropyl nitroxide and its β²H-labelled homologue has been examined by UV and EPR. The bimolecular reaction does not show reversible formation of a dimer, but exhibits an isotope effect (k_H/k_d)_30°C?9 which shows that the rupture of the CH bond is involved in the slow step of the decomposition. The β proton coupling constant, determined by NMR, is +1.84 G.     

Evidence for ψ' decays into γπ0 and γη

The decays ψ'→γπ(0), γη and γη' are studied using data collected with the BESIII detector at the BEPCII e(+)e(-) collider. The processes ψ'→γπ(0) and ψ'→γη are observed for the first time with signal significances of 4.6σ and 4.3σ, respectively. The branching fractions are determined to be B(ψ'→γπ(0))=(1.58±0.40±0.13)×10(-6), B(ψ'→γη)=(1.38±0.48±0.09)×10(-6), and B(ψ'→γη')=(126±3±8)×10(-6), where the first errors are statistical and the second ones systematic.     

Evidence for the decay D0-->K(-)pi(+)pi(-)e(+)nu(e)

Using a 281 pb{-1} data sample collected at the psi(3770) with the CLEO-c detector, we present the first absolute branching fraction measurement of the decay D0-->K(-)pi(+)pi(-)e(+)nu(e) at a statistical significance of about 4.0 standard deviations. We find 10 candidates consistent with the decay D0-->K(-)pi(+)pi(-)e(+)nu(e). The probability that a background fluctuation accounts for this signal is less than 4.1 x 10{-5}. We find B(D0-->K(-)pi(+)pi(-)e(+)nu(e)) = [2.8{-1.1}{+1.4}(stat)+/-0.3(syst)]x10{-4}. By restricting the invariant mass of the hadronic system to be consistent with K1(1270), we obtain the product of branching fractions B(D{0}-->K{1}{-}(1270)e{+}nu{e})xB(K1-(1270)-->K{-}pi{+}pi{-})=[2.5{-1.0}{+1.3}(stat)+/-0.2(syst)]x10{-4}. Using B(K1-(1270)-->K{-}pi{+}pi{-})=(33+/-3)%, we obtain B(D{0}-->K{1}{-}(1270)e{+}nu{e})=[7.6{-3.0}{+4.1}(stat)+/-0.6(syst)+/-0.7]x10{-4}. The last error accounts for the uncertainties in the measured K1-(1270)-->K{-}pi{+}pi{-} branching fractions.     

First search for the flavor changing neutral current decay D0-->gammagamma

Using 13.8 fb(-1) of data collected at or just below the Upsilon(4S) with the CLEO detector, we report the result of a search for the flavor changing neutral current process D0-->gammagamma. We observe no significant signal for this decay mode and determine 90% confidence level upper limits on the branching fractions B(D0-->gammagamma)/B(D0-->pi(0)pi(0))<0.033 and B(D0-->gammagamma)<2.9 x 10(-5).     

ConFlo III - an interface for high precision delta(13)C and delta(15)N analysis with an extended dynamic range

A newly developed interface coupling a CHN combustion device (elemental analyser 'EA') to an isotope ratio mass spectrometer is described and evaluated. The purpose of the device is to extend the dynamic range of delta(13)C and delta(15)N analysis from less than 2 orders of magnitude to more than 3 orders of magnitude. Carbon isotope ratio measurements of atropine as a model compound have been performed analysing between 1 μg to 5 mg C with acceptable to excellent precision (0.6 to 0.06 per thousand, delta-notation). The correction due to the blank signal is critical for sample amounts smaller than 4 μg C. The maximum sample weight is determined by the combustion capacity of the EA. Larger sample amounts are measured using dilution of a small part of the EA effluent with helium. The dilution mechanism works virtually free of isotope fractionation. Copyright 1999 John Wiley & Sons, Ltd.