The b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) and a1Delta(a2) --> X21 Transitions of SbF, SbCl, SbBr, and SbI

Emission spectra of the a1Delta(a2) --> X21 and b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) transitions of SbF, SbCl, SbBr, and SbI have been observed in the near-infrared spectral region. The antimony halide radicals were generated and excited in a fast-flow system by reaction of antimony vapor (Sbx) with the halides and microwave-discharged oxygen. The NIR chemiluminescence was measured with a Fourier-transform spectrometer equipped with Ge and InSb detectors. The spectra contain the known b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) transitions in the range 730-910 nm and the hitherto unknown a1Delta(a2) --> X21 transitions in the range 1600-1900 nm. Vibrational analyses have yielded improved molecular constants for the X10(+), X21, and b0(+) states and the following constants of the a2 states (in cm-1): 121SbF: Te = 6815.6(5), omegae = 615.75(3), omegaexe = 2.62(1); 121Sb35Cl: Te = 6546.3(2), omegae = 379.8(1), omegaexe = 1.20(2); 121Sb79Br: Te = 6496.4(4), omegae = 265.9(2), omegaexe = 0.55(3); 121SbI: Te = 6366.7(3), omegae = 214.20(5), omegaexe = 0.430(9), where the numbers in parentheses are the standard deviations of the parameters. Copyright 1999 Academic Press.     

Anomalously hindered E2 strength B(E2;2+(1)-->0+) in 16C

The electric quadrupole transition from the first 2(+) state to the ground 0(+) state in 16C is studied through measurement of the lifetime by a recoil shadow method applied to inelastically scattered radioactive 16C nuclei. The measured mean lifetime is 77+/-14(stat)+/-19(syst) ps. The central value of mean lifetime corresponds to a B(E2;2+(1)-->0(+)) value of 0.63e(2) fm(4), or 0.26 Weisskopf units. The transition strength is found to be anomalously small compared to the empirically predicted value.     

Differential cross section and photon-beam asymmetry for the gamma n --> K+ Sigma- reaction at E gamma = 1.5-2.4 GeV

Differential cross sections and photon-beam asymmetries have been measured for the gamma n --> K+ Sigma- and gamma p --> K+Sigma0 reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of E gamma = 1.5-2.4 GeV at 0.6 < cos ThetacmK< 1. The cross section ratio of sigma K+ Sigma-/sigma K+ Sigma0, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K+ Sigma- reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K+ Sigma- and K+ Sigma0 reactions cannot be explained by simple theoretical considerations based on Regge model calculations.     

High-Resolution Fourier Transform Emission Spectroscopy of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) Transition of the PN(+) Ion

Ultraviolet emission spectrum of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) transition of the PN(+) ion has been observed at a resolution of 0.05 cm(-1) by a Fourier transform spectrometer. The rotational analysis led to a great improvement of rotational constants in the B(2)Sigma(+) (v = 0) and X(2)Sigma(+) (v = 0) states as well as to the first determination of centrifugal distortion constants for both levels and spin-rotation interaction constant in the X(2)Sigma(+) (v = 0) state. Rotational perturbation in the B(2)Sigma(+) (v = 0) state was observed. Copyright 2000 Academic Press.     

Fourier Transform Spectroscopy of the A'(1)Pi-X(1)Sigma(+) System of CaO

The A'(1)Pi-X(1)Sigma(+) near-infrared system of CaO was observed for the first time at high resolution using a Fourier transform spectrometer. The A'(1)Pi-X(1)Sigma(+) chemiluminescence was excited in a Ca + N(2)O flame produced in a Broida-type oven. More than 3000 rotational lines, classified into 19 bands involving the A'(1)Pi 0 /= 2) levels with the nearby b(3)Sigma(+) (v-2) levels has been detected. An extended set of A'(1)Pi (v = 0-3) data has been obtained which is suitable for use in a future multistate deperturbation analysis of the a(3)Pi approximately A'(1)Pi approximately b(3)Sigma(+) approximately A(1)Sigma(+) complex of excited states. The new near-infrared spectra of the A'(1)Pi-X(1)Sigma(+) transition of CaO also permits the first direct high-resolution linkage between the orange and green systems and the near-infrared bands. Copyright 2000 Academic Press.     

The (1)(3)Pi Electronic State of LaF

Rotational studies of bands of the infrared systems (1)(3)Pi-->(1)(3)Delta and (1)(3)Pi(1)-->X(1)Sigma(+) of lanthanum monofluoride were carried out with the aim of characterizing the (1)(3)Pi state, assuming the previous representations of X(1)Sigma(+) and (1)(3)Delta (1-3). The vibrational levels of (1)(3)Pi involved in the analyzed transitions were v=0, 1, 2 of the Omega=0 component, v=0, 1 of the Omega=1 component, and v=0 of the Omega=2 component. Perturbations were observed in both systems which were ascribed to spin-uncoupling interactions between (1)(3)Pi(2)(v=0) and (1)(3)Pi(1)(v=1) levels. A 9x9 matrix representation at equilibrium of the complex of interacting levels (v=0, 1, 2) was constructed, each diagonal v-block corresponding to a triplet model of the rovibrational (3)Pi Hamiltonian. The wavenumbers of some 1910 lines in the two systems were simultaneously fitted (rms error of the fit of about 0.0053 cm(-1)), thus yielding a consistent set of accurate spectroscopic constants for the (1)(3)Pi state; the spin-uncoupling interaction parameter was determined as B(Pi)(0, 1)=0.010917(13) cm(-1). Copyright 2001 Academic Press.     

Atom abstraction in the scattering of state-selected NO+(X1Sigma(+)) on O/Al(111)

The reactive scattering of state-selected NO+(X1Sigma(+)) on oxygen-covered Al(111) is explored at hyperthermal collision energies. Relative ion yields and mean translational energies of scattered NO-2 are presented as a function of oxygen exposure and NO+ collision energy. Above the 9+/-1 eV threshold for reaction, NO-2 products emerge with an average kinetic energy that depends linearly on incident NO+ energy. The formation of NO-2 is assigned to the direct, Eley-Rideal abstraction of an adsorbed O atom by an incident NO molecule.     

First measurement of form factors of the decay Xi(0) --> Sigma(+)e(-)nu macro(e)

We present the first measurement of the form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for the decay Xi(0)-->Sigma(+)e(-)nu macro(e) using the KTeV (E799) beam line and detector at Fermilab. From the Sigma(+) polarization measured with the decay Sigma(+)-->p pi(0) and the e(-)-nu; correlation, we measure g(1)/f(1) to be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming the SU(3)(f) (flavor) values for g(2)/f(1) and f(2)/f(1). Our results are all consistent with exact SU(3)(f) symmetry.     

Evidence for the decay sigma+ --> pmu+ mu-

We report the first evidence for the decay Sigma(+)-->pmu(+)mu(-) from data taken by the HyperCP (E871) experiment at Fermilab. Based on three observed events, the branching ratio is B(Sigma(+)-->pmu(+)mu(-))=[8.6(+6.6)(-5.4)(stat)+/-5.5(syst)]x10(-8). The narrow range of dimuon masses may indicate that the decay proceeds via a neutral intermediate state, Sigma(+)-->pP(0),P0-->mu(+)mu(-) with a P0 mass of 214.3+/-0.5 MeV/c(2) and branching ratio B(Sigma(+)-->pP(0),P0-->mu(+)mu(-))=[3.1(+2.4)(-1.9)(stat)+/-1.5(syst)]x10(-8).     

The Comet-Tail (A(2)Pi(i)-X(2)Sigma(+)) System of (12)C(16)O(+): A Reinvestigation

The emission spectrum of the comet-tail (A(2)Pi(i)-X(2)Sigma(+)) system of (12)C(16)O(+) produced in the cathode glow of a hollow-cathode discharge tube and photographed in the spectral region 3345-8500 ? at high resolution was reinvestigated. Detailed rotational analysis of 10 bands involving 5 vibrational levels v = 0 to 4 of each of the A and X states was carried out. Spin-splitting of the rotational levels was observed for the analyzed bands. The observed intensity distribution of the branches is found to be in good agreement with theoretical calculations. Molecular constants for both the A and X states were obtained from a global fit of the present data of the A-X system and the infrared and microwave data available from the literature for v = 0, 1, 2, 3, and 4 of state X, using effective Hamiltonian for the A(2)Pi state and matrix elements for both A and X states. The present work suggests that the A(2)Pi(i) state changes from Hund's case (a) at low J values to Hund's case (b) at high J values. Copyright 2000 Academic Press.     

Observation of B+-->a1+(1260)K0 and B0-->a1-(1260)K+

We present branching fraction measurements of the decays B(+)-->a(1)(+)(1260)K(0) and B(0)-->a(1)(-)(1260)K(+) with a(1)(+/-)(1260)-->pi(-/+)pi(+/-)pi(+/-). The data sample corresponds to 383 x 10(6) BB pairs produced in e(+)e(-) annihilation through the Upsilon(4S) resonance. We measure the products of the branching fractions B(B(+)-->a(1)(+)(1260)K(0)B(a(1)(+)(1260)-->pi(-)pi(+)pi(+))=(17.4+/-2.5+/-2.2) x 10(-6) and B(B(0)-->a(1)(-)(1260)K(+)B(a(1)(-)(1260)-->pi(+)pi(-)pi(-)) = (8.2+/-1.5+/-1.2) x 10(-6). We also measure the charge asymmetries A(ch)(B(+)-->a(1)(+)(1260)K(0) = 0.12+/-0.11+/-0.02 and A(ch)(B(0)-->a(1)(-)(1260)K+) = -0.16+/-0.12+/-0.01. The first uncertainty quoted is statistical and the second is systematic.     

Observation of Psi(3770)-->gammachi(c1)-->gammagammaJ/Psi

From e(+)e(-) collision data acquired with the CLEO detector at the Cornell Electron Storage Ring, we observe the non-DD(_) decay Psi(3770))-->gammachi(c1) with a statistical significance of 6.6 standard deviations, using the two-photon cascades to J/Psi and J/Psi-->l(+)l(-). We determine sigma(e(=)e(-)-->Psi(3770))xBeta(Psi(3770)-->gammachi(c1))=(18.0 +/- 3.3 +/- 2.5) pb and branching fraction Beta(Psi(3770)-->gammachi(c1)=(2.8 +/- 0.5+/-0.4) x 10(-3). We set 90% C.L. upper limits for the transition to chi(c2) (chi(c0)): sigma x Beta<5.7 pb (<282 pb) and Beta<0.9 x 10(-3) (<44 x 10(-3)). We also determine Gamma(Psi(3770)gammachi(c1))/Gamma(Psi(3770)-->pi(+)pi(-)J/Psi)=1.5 +/- 0.3 +/- 0.3 (>1.0 at 90% C.L.), which bears upon the interpretation of X(3872).     

Direct CP violating asymmetry in B0-->K+pi- decays

We present a measurement of the direct CP violating asymmetry in the decay B0-->K+pi(-) using a data sample of 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We observe a total signal yield of nK-(pi(+))+nK+(pi(-))=1606+/-51 decays and measure the asymmetry (nK-(pi(+))-nK+(pi(-)))/(nK-(pi(+))+nK+(pi(-)))=-0.133+/-0.030(stat)+/-0.009(syst). The probability of observing such an asymmetry in the absence of direct CP violation is 1.3x10(-5), corresponding to 4.2 standard deviations.     

Experimental evidence for a light and broad scalar resonance in D(+) --> pi(-)pi(+)pi(+) decay

From a sample of 1172 +/- 61 D(+)-->pi(-)pi(+)pi(+) decays, we find gamma(D(+)-->pi(-)pi(+)pi(+))/gamma(D(+)-->K-pi(+)pi(+)) = 0.0311 +/- 0.0018(+0.0016)(-0.0026). Using a coherent amplitude analysis to fit the Dalitz plot of these decays, we find strong evidence that a scalar resonance of mass 478(+24)(-23) +/- 17 MeV/c(2) and width 324(+42)(-40) +/- 21 MeV/c(2) accounts for approximately half of all decays.     

The Near-Infrared (3)Phi --> (1)(3)Delta Transition of LaF

Rotational analyses of 32 subbands of the near-infrared (3)Phi --> (1)(3)Delta system of LaF have been carried out, involving the levels v = 0-7 of the two states. The three subsystems were first treated as separate singlet systems, directly at equilibrium. Perturbations were revealed in the lower state, ascribed to spin-uncoupling interactions between (1)(3)Delta(3)(v) and (1)(3)Delta(2)(v + 1) levels. A 21 x 21 matrix representation at equilibrium of the complex of interacting levels (v = 0-6) was then constructed, each diagonal v-block corresponding to a triplet model of the rovibrational (3)Delta Hamiltonian. The observed perturbations were completely reduced in the harmonic oscillator approximation with an experimental value of the interaction parameter B(Delta)(0,1) = 0.01322(2) cm(-1). The wavenumbers of some 4500 lines of the system were fitted with an rms error of about 0.005 cm(-1). (Line lists are available in electronic form via http://www-obs.univ-lyon1.fr/~ABernard/index.html.) Copyright 2000 Academic Press.     

Measurements of branching fractions for B --> K pi and B --> pi pi decays

We report measurements of branching fractions for B --> K pi and B --> pi pi decays based on a data sample of 449 x 10(6) BB[over] pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We also measure the ratios of partial widths for B-->Kpi decays, namely R(c) identical with 2Gamma(B(+) --> K(+) pi(0))/Gamma(B(+) --> K(0) pi(+)) = 1.08+/-0.06+/-0.08 and R(n) identical with Gamma(B(0) --> K(+) pi(-))/2 Gamma(B(0) --> K(0) pi(0)) = 1.08+/-0.08+/-0.08, where the first and the second errors are statistical and systematic, respectively. These ratios are sensitive to enhanced electroweak penguin contributions from new physics; the new measurements are, however, consistent with standard model expectations.     

The Radial Hamiltonians for the X(1)Sigma(+) and B(1)Sigma(+) States of HCl

All literature vibration-rotational and pure rotational transition energies for the ground X(1)Sigma(+) electronic state of H(35)Cl, H(37)Cl, D(35)Cl, and D(37)Cl, along with the entire collection of electronic B(1)Sigma(+) --> X(1)Sigma(+) emission data for the four isotopomers, have been used in a least-squares fit of compact analytic Born-Oppenheimer potential functions for the B(1)Sigma(+) and X(1)Sigma(+) electronic states. Additional functions related to the adiabatic and nonadiabatic corrections have also been determined. Separate least-squares fits were made according to the hamiltonian operators of J. K. G. Watson (J. Mol. Spectrosc. 80, 411 (1980)) and R. M. Herman and J. F. Ogilvie (Adv. Chem. Phys. 103, 187 (1998)). The results from the separate analyses demonstrate clearly that the two hamiltonian operators are essentially equivalent, both achieving equally satisfactory representations of the spectral data, and furnishing virtually identical Born-Oppenheimer potential functions. Fully quantum-mechanical vibrational eigenvalues and rotational perturbation series parameters B(v)-O(v) are presented for the lower levels of the X(1)Sigma(+) ground state for which infrared and/or microwave data are available (v" 相似文献   

Laser-Induced Fluorescence and Fourier Transform Spectroscopy of NiCl: Identification of a Low-Lying (2)Sigma(+) State (1768 cm(-1))

From a comparison with the spectrum of NiF, a low-lying (2)Sigma(+) state is expected to lie in the first 2000 cm(-1) above the ground X(2)Pi(3/2) state of NiCl. The identification of this (2)Sigma(+) (v = 0) state (at 1768 cm(-1)) has been carried out through the analysis of two electronic transitions (2)Pi(3/2)-(2)Sigma(+) (22 720 cm(-1)) and (2)Pi(1/2)-(2)Sigma(+) (23 210 cm(-1)) recorded by high-resolution Fourier transform spectroscopy. Dispersed fluorescence spectroscopy allowed these transitions to be located on an absolute energy-level diagram that includes the previously studied electronic states. Copyright 2000 Academic Press.     

The Rotational Spectrum of SO(2) and the Determination of the Hyperfine Constants and Nuclear Magnetic Shielding Tensors of (33)SO(2) and SO(17)O

Rotational analyses of the B(2)Sigma(+)(u) --> X(2)Sigma(+)(g) system of the (14)N(+)(2) molecule have been extended to include the vibrational levels up to v' = 4. Spectral data from 20 bands obtained from high-resolution Fourier transform spectrometry of a hollow-cathode and a Pointolite lamp were included in the analysis. A global deperturbation yielded molecular parameters of the highly perturbed B(2)Sigma state and interaction parameters A(2)Pi(u) approximately B(2)Sigma(u) with a standard deviation of 0.011 cm(-1). Rotational term values of the B(2)Sigma(+) state were also determined. New perturbations in the B(2)Sigma(+) (v = 0) level have been observed at N approximately 85 and N approximately 96. Copyright 2000 Academic Press.     

Observation of the psi(4415)-->DD2*(2460) decay using initial-state radiation

We report measurements of the exclusive cross section for e(+)e(-)-->D(0)D(-)pi(+) over the center-of-mass energy range 4.0 GeV to 5.0 GeV with initial-state radiation and the first observation of the decay psi(4415)-->D(0)D(-)pi(+). From a study of the resonant substructure in psi(4415) decay we conclude that the psi(4415)-->D(0)D(-)pi(+) decay is dominated by psi(4415)-->DD(2)(*)(2460). We obtain B(psi(4415)-->D(0)D(-)pi(nonresonant)(+))/B(psi(4415)-->DD(2)(*)(2460)-->D(0)D(-)pi(+))<0.22 at 90% C.L. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 fb(-1).