Decay Constants of Heavy-Light Mesons

The decay constants of the heavy-light pseudoscalar mesons are studied in a high statistics run using the Wilson action at $\beta=6.0$ and $\beta=6.2$, and the clover action at $\beta=6.0$. The systematics of $O(a)$ discretisation errors are discussed. Our best estimates of the decay constants are: $f_D$ = 218(9) MeV, $f_D/f_{Ds}$ = 1.11(1) and we obtain preliminary values for $f_B$.Comment: at the Dallas Lattice Conference, October 1993. 3 pages in a single postscript file, uuencoded form. Rome Preprint 93/98

High order harmonic generation from SF6: Deconvolution of macroscopic effects

Citation: Wilson, B. P., Fulfer, K. D., Mondal, S., Ren, X., Tross, J., Poliakoff, E. D., . . . Trallero-Herrero, C. (2016). High order harmonic generation from SF6: Deconvolution of macroscopic effects. Journal of Chemical Physics, 145(22), 11. doi:10.1063/1.4971244We measure high order harmonics from the molecule SF6 over a large range of phase matching conditions and observe several features in the harmonics that are largely independent of such macroscopic conditions. The experimental data are then compared to the quantitative rescattering theory for the generation of harmonics from three orbitals. With this comparison, we are able to assign spectroscopic features in the harmonics to contributions from 1t(1g) (HOMO) and 5t(1u) (HOMO-1) orbitals. Published by AIP Publishing

Atomic photoionization experiment by harmonic-generation spectroscopy

Citation: Frolov, M. V., Sarantseva, T. S., Manakov, N. L., Fulfer, K. D., Wilson, B. P., Tross, J., . . . Trallero-Herrero, C. A. (2016). Atomic photoionization experiment by harmonic-generation spectroscopy. Physical Review A, 93(3), 5. doi:10.1103/PhysRevA.93.031403Measurements of the high-order-harmonic generation yield of the argon (Ar) atom driven by a strong elliptically polarized laser field are shown to completely determine the field-free differential photoionization cross section of Ar, i.e., the energy dependence of both the angle-integrated photoionization cross section and the angular distribution asymmetry parameter

Tracking the ultraviolet-induced photochemistry of thiophenone during and after ultrafast ring opening

Photoinduced isomerization reactions lie at the heart of many chemical processes in nature. The mechanisms of such reactions are determined by a delicate interplay of coupled electronic and nuclear dynamics occurring on the femtosecond scale, followed by the slower redistribution of energy into different vibrational degrees of freedom. Here we apply time-resolved photoelectron spectroscopy with a seeded extreme ultraviolet free-electron laser to trace the ultrafast ring opening of gas-phase thiophenone molecules following ultraviolet photoexcitation. When combined with ab initio electronic structure and molecular dynamics calculations of the excited- and ground-state molecules, the results provide insights into both the electronic and nuclear dynamics of this fundamental class of reactions. The initial ring opening and non-adiabatic coupling to the electronic ground state are shown to be driven by ballistic S–C bond extension and to be complete within 350 fs. Theory and experiment also enable visualization of the rich ground-state dynamics that involve the formation of, and interconversion between, ring-opened isomers and the cyclic structure, as well as fragmentation over much longer timescales

A High Statistics Lattice Calculation of fBstaticf^{static}_B at β=6.2\beta=6.2 Using the Clover Action

We present a calculation of $f_B$ in the static limit, obtained by numerical simulation of quenched QCD, at $\beta=6.2$ on a $18^3 \times 64$ lattice, using the SW-Clover quark action. The decay constant has been extracted by studying heavy(static)-light correlation functions of different smeared operators, on a sample of 220 gauge field configurations. We have obtained $f_B^{static}=(290 \pm 15 \pm 45)$ MeV, where the first error comes from the uncertainty in the determination of the matrix element and the second comes from the uncertainty in the lattice spacing. We also obtain $M_{B_s}-M_{B_d}= (70 \pm 10)$ MeV and $f^{stat}_{B_s}/f^{stat}_{B_d}=1.11(3)$. A comparison of our results with other calculations of the same quantity is made.Comment: 12 pages, LaTex, 3 figs. (figures not included; available upon request from [email protected]) ROME prep. 94/981, 18 February 199

Effect of a Community Popular Opinion Leader HIV/STI Intervention on Stigma in Urban, Coastal Peru

Evaluating interventions that reduce HIV stigma may help to craft effective stigma-reduction programs. This study evaluates the effects of a community popular opinion leader HIV/STI intervention on stigma in urban, coastal Peru. Mixed effects modeling was used to analyze data on 3,049 participants from the Peru site of the NIHM collaborative trial. Analyses looked at differences between the comparison and intervention groups on a stigma index from baseline to 12- and 24-month follow-up. Sub-analyses were conducted on heterosexual-identified men (esquineros), homosexual-identified men (homosexuales), and socially marginalized women (movidas). Compared to participants in the comparison group, intervention participants reported lower levels of stigma at 12- and 24-month follow-up. Similar results were found within esquineros and homosexuales. No significant differences were found within movidas. Findings suggest that interventions designed to normalize HIV prevention behaviors and HIV communication can reduce HIV-related stigma and change community norms