Measurement of the differential cross section for the production of an isolated photon with associated jet in ppbar collisions at sqrt(s)=1.96 TeV

The process ppbar -> photon + jet + X is studied using 1.0 fb^-1 of data collected by the D0 detector at the Fermilab Tevatron ppbar collider at a center-of-mass energy sqrt(s)=1.96 TeV. Photons are reconstructed in the central rapidity region |y_gamma|<1.0 with transverse momenta in the range 30<Pt_gamma<400 GeV while jets are reconstructed in either the central |y_jet|15 GeV. The differential cross section d^3sigma/dPt_gamma dy_gamma dy_jet is measured as a function of Pt_gamma in four regions, differing by the relative orientations of the photon and the jet in rapidity. Ratios between the differential cross sections in each region are also presented. Next-to-leading order QCD predictions using different parameterizations of parton distribution functions and theoretical scale choices are compared to the data. The predictions do not simultaneously describe the measured normalization and Pt_gamma dependence of the cross section in any of the four measured regions.Comment: 13 pages, 10 figure

Multigas survey from low-T° fumaroles in a tropical environment.: Effects from internal and external forcing: example from La Soufriere de Guadeloupe (FWI).

International audienceFumarolic gas survey of dormant volcanoes is fundamental because the compositional and flux changes in gas emissions have actually been recognised as signals of unrest or even precursors of eruptions on several dormant volcanoes in hydrothermal unrest [1-5]. Here we report on the chemical compositions (CO2, H2S, SO2, H2) and mass fluxes of fumarolic gas emissions from the low-temperature (from 97° to 104°C) volcanic-hydrothermal system of La Soufrière de Guadeloupe (Lesser Antilles). These data, since 2017, are acquired from portable MultiGAS (measurements performed monthly) and two permanent MultiGAS stations (4 automated 20’ measurements per day). These MultiGAS data are discussed along with other geochemical and geophysical parameters monitored at OVSG, such as the complete chemical gas composition sampled by Giggenbach bottles, fumarole temperature and volcanic seismicity in order to track the deep-sourced magmatic signal and detect potential signs of unrest [6]. However, dealing with the MultiGAS data in a low-T fumarolic system in a tropical environment is not straightforward due to external forcing. Hence, interpretation of the observed chemical changes must consider the dynamics of (i) scrubbing processes by the hydrothermal system and the perched volcanic pond [7], (ii) rainfall and the groundwater circulation (i.e. rainy vs non-rainy seasons, extreme events), (iii) water-gas-rock interactions [7], (iv) plume condensation, (v) sulphur deposition and remobilization, and (vi) gas-atmosphere chemical interaction. [1] Giggenbach and Sheppard, 1989; [2] Symonds et al., 1994; [3] Hammouya et al., 1998; [4] De Moor et al., 2016; [5] Allard et al., 2014; [6] Moretti et al., submitted; [7] Symonds et al., 200