429 research outputs found
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
ROTATIONAL LINE STRENGTHS FOR THE 1.27 ELECTRONIC TRANSITION OF
No full textAuthor Institution: Optical Technology Division, National Institute of Standards and TechnologyAccurate line parameters for the near-infrared electronic bands of are important for atmospheric modeling and remote sensing. Here, we report measurements of the rotional linestrengths and pressure-broadening coefficients for the component of the a band of near . The measurements have been measured at resolution and sample pressures from 13kPa to 101kPa using a Fourier-transform infrared spectrometer and a White cell with an optical pathlength of 84 m. The rotational lines follow magnetic-dipole selection rules and have intensities proportional to the sample pressure. The resolved rotational structure overlaps the electric-dipole-allowed collision-induced continuum absorption which is due to binary collisions and which dominates at higher sample pressures. The present measurements will be compared to recent results by other investigators. Efforts are presently underway to determine continuum parameters for the collision-induced background absorption
WIDE-BAND TUNABLE DIODE LASER HETERODYNE MEASUREMENTS
No full text J. P. Sattler, T. L. Worchesky, K. J. Ritter, and W. J. Lafferty, Opt. Lett. 5, 21 (1980)Author Institution:A technique for rapid, accurate, and copious diode laser heterodyne measurements of infrared absorption frequencies will be discussed in By use of a wideband (3 dB width, 1.2 GHz) HgCdTe photomixer and a laser local oscillator, absorptions lying within 9 GHz of a emission line may be measured with care to within 6 MHz. The data from accurate infrared heterodyne measurements of 1,1-difluoroethylene, when supplemented with existing microwave data on the ground state, permit the calculation of submilimeter wave laser emission frequencies to within a few megahertz. Similar measurements on carbonyl sulfide increase its utility as a secondary frequency standard
LINE INTENSITIES FOR THE 10 BANDS OF
No full textAuthor Institution: Analytical Chemistry Division, CSTL, National Institute of Standards and Technology; Optical technology Division, Physics Laboratory, National Institute of Standards and Technology; Laboratoire de photophysique Moleculaire, CNRS, Universite Paris Sub; Laboratoire de Physique Moleculaire et Applications, CNRS, Universite Paris Sub; Laboratoire de Physique Moleculaire et Applications, Jet Propulsions LaboratoryUsing both high resolution and medium resolution Fourier transform spectra recorded at LPMA Orsay and Kitt Peak, and at NIST Gaithersburg respectively, it has been possible to measure a large set of individual line intensities for the and bands of in the Spectral region. These intensities were introduced in a least squares fit calculation allowing one to get the expansion of the transition moment operator of the and bands of . For these intensities calculations, the theoretical model takes into account the vibration-rotation interactions linking the upper levels involved in the and interacting bands of . Finally a synthetic spectrum of the 10 bands of has been generated, using for the line intensities the dipole moment expansion determined in this work and for the lined positions the parameters and the Hamiltonian matrix given in a previous analysis [J.-M. Flaud, A. Perrin, L.M. Salah, W. J. Lafferty and G. Guelachvili, J. Mol. Spectrose. 160, 272-278 (1993)
DIODE LASER STUDY OF THE FUNDAMENTAL OF
No full text W. J. Lafferty, A. G. Maki, and E. K. Plyler, J. Chem. Phys. 40, 224 (1964). A. W. Mantz, P. Connes, G. Guelachvili, and C. Amiot, J. Mol. Spectrosc. 54, 43 (1975).""Author Institution: Scientific Research Staff Ford Motor Company; Department of Physics, The University of MichiganWe have used current-tunable, thin-film PbTe diode lasers to obtain Doppler-limited resolution of the band of in the region 1565-1600 . Roughly 60\% of the interval was covered using different modes of 2 lasers, each mode giving a tuning range of 1-3 cm, Calibration was obtained with HO and NH, while the frequency scale was given by the fringes of a 4-cm Ge etalon, recorded simultaneously using a double beam technique. Near 1600 cm a set of strong regularly spaced lines stands out, which is the R branch of the ground state transition. This band as wel as the ``hot” bands due to the bending vibration indicate a linear structure for the molecule. Preliminary values in cm for the ground state are 1587.392, B^{\prime\prime} - 0.07557, and B - B. This B^{\prime\prime} value differs from that reported by Lafferty et al., but agrees with that by Mantz et al. The next 2 strongest series were interpretable as a band with = 1580.910, B = 0.07606, B - 0.07646, B - B = 4,178 X 10, B - B = 5.259 10. These B values agree with Assignment 2 by Lafferty et al. The assignment of the ground state transition and the shift of the “hot” bands toward lower frequency were substantiated by temperature-difference FTS spectra
Measurement of the effective B0s→K+K− lifetime
No full textA measurement of the effective lifetime is presented using approximately 37 pb−1 of data collected by LHCb during 2010. This quantity can be used to put constraints on contributions from processes beyond the Standard Model in the meson system and is determined by two complementary approaches as
τKK=1.440±0.096 (stat)±0.008 (syst)±0.003 (model) ps
VIRATIONAL, ROTATIONAL, AND TUNNELING DEPENDENCE OF VIBRATIONAL PREDISSOCIATION IN THE HF DIMER
No full text A. S. Pine and W.J. Lafferty, J. Chem. Phys. 28, 2154 (1983). A. S. Pine, W. J. Lafferty. and B. J. Howard, J. Chem. Phys. 81, 2939 (1984). Z. S. Huang. K. W. Jucks and R. E. Miller. J. Chem. Phys. 85, 3338 (1986).Author Institution: Molecular Spectroscopy Division, National Bureau of StandardsAs observed , there is a marked vibrational dependence to the vibrational predissociation rate in the HF dimer with the free-H stretching mode, , much longer lived than the bound-H stretching mode, . Using an optothermal (bolometer-detected) crossed molecular-beam color-center laser spectrometer, we have achieved sufficient resolution to measure the narrow homogeneous linewidths for the band with high precision (). We observe a substantial K, but negligible J. dependence for the predissociation linewidths, and a smaller, but statistically significant, dependence on the tunneling state. For the symmetric lower tunneling level of , the predissociation linewidths are almost twice as broad as the . The widths for the antisymmetric tunneling level are roughly 50\% greater than for the symmetric level for and about for . We also report improved measurements of the broader band predissociation linewidths with reduced spectral congestion and afforded by the low effective temperatures of the adiabatic expansion
HIGH RESOLUTION FT.IR SPECTROSCOPY OF TRANS-1,2-DIFLUOROETHYLENE.D2
No full textS. Saebo and H. Sellers, J. Phys. Chem. 92, 4266 (1988). N. C. Craig, D. W. Brancon and W. J. Lafferty, Forty-Fifth Symposlum on Molecular Spectroscopy, Columbus, OH, MF11. N. C. Craig and J.Overend J. Chem. Phys. 51, 1127 (1969).""Author Institution: Department of Chemistry, Oberlin College; Molecular Physics Division, National Institute of Standards and TechnologyA complete structure of trans-1,2-difluoroethylene, which is a non-polar molecule, would assist in interpreling the surprisingly greater energy of this isomer in comparison with its cis We are in the process of obtaining high resolution () spectra of several bands of three isotopomers of this near-symmetric prolate top molecule with the goal of finding precise ground state rotational constants and a reliable structure. Last year we reported an analysis of three bands in the spectrum of the This year, we report on the preliminary analysis of two bands in the spectrum of the species. From the A-type band at 1176 which is due to antisymme\""oe CF stretching. we obtain initial values of and equal to 0.134021(5) and 0.121108(5) . The higher K levels of this band are slightly perturbed, but a set of upper state constants can be obtained by fitting all observed transitions through K-6. The two ground state constants are in good agreement with values calculated from geometric parameters in which the CCF bond angle and CF bond length were fit to moments of inertia for the species while fixing other parameters to those transferred from the cis isomer. In the trans isomer, the CCF bond angle is smaller, and the CF bond length is longer. In addition the A/B-hybrid band at 1331 has been examined. This band, which is due to the combination tone, is heavily perturbed. The A-type O-branch is split into two strong components separated by 1
VERY HIGH RESOLUTION FOURIER TRANSFORM AND DIODE LASER SPECTRA OF THE BAND OF
No full text. Flicker, R. S. McDowell, N. G. Nereson, and K. Fox, Molecular Spectroscopy Symposium, The Ohio State University, Paper TB5 (1997). A. S. Pine and W. J. Lafferty. Molecular Spectroscopy Symposium, The Ohio State University, Paper ME12 (1978). J. T. Hougen, J. Mol. Spectrosc. 82, 92 (1980).Author Institution:The infrared spectrum of the band of ethane has been recorded with a resolution of using a Fourier transform spectrometer. In addition, twelve Q-branches ranging from have been measured with a diode laser spectrometer capable of Doppler limited resolution (). The line splittings reported by Flicker et , in the Q-branches of this band have been verified and observed in the P- and R-branches as well. Quantum number assignments have been made with the aid of combination differences calculated from well determined ground state Nuclear spin statistics clearly show that the individual transitions are split into their two torsional components even though torsional splitting for this band would be expected to be un-resolvable. The observed splitting is J dependent and varies from K to K. The large splitting observed probably results from an interaction of the state with the components of the v - 3 level of the torsional vibration. Preliminary results will be reported. The most recent theoretical work on this molecule was presented by Hougen and some of the above studies were undertaken as a sequel to the recommendations in his paper
Observation of double charm production involving open charm in pp collisions at sqrt{s}=7 TeV
No full textThe production of J/Ψ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7TeV using an integrated luminosity of 355 pb -1 collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured J/Ψ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions
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