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In the past decades, short baseline neutrino oscillation studies around experimental or commercial reactor cores have revealed two anomalies. The first one is linked to the absolute flux and the second one to the spectral shape. The first anomaly, called Reactor Antineutrino Anomaly (RAA), could be explained by the introduction of a new oscillation of antineutrinos towards a sterile state of the eV mass. The \stereo detector has been taking data since the end of 2016 at 10~m from the core of the Institut Laue-Langevin research reactor, Grenoble, France. The separation of its Target volume along the neutrino propagation axis allows for measurements of the neutrino spectrum at multiple baselines, providing a clear test of an oscillation at short baseline. In this contribution, a special focus is put on the data analysis and the neutrino extraction using the Pulse Shape Discrimination observable. The results from 119 days of reactor turned on and 210 days of reactor turned off are then reported. The resulting antineutrino rate is (365.7~$\pm$~3.2) \anue /day. The test of a new oscillation towards a sterile neutrino is found to be compatible with the non-oscillation hypothesis and the best fit of the RAA is excluded at 99\% C.L., Comment: 8 pages, 11 figures, Contribution to the 2019 EW/QCD/Gravitation session of the 54th Rencontres de Moriond

International audience; Missing transverse momentum, $E$$^{miss}_{T}$, is commonly used to study the production of weakly interacting particles. The missing transverse momentum significance, $S$, helps to separate events in which the reconstructed $E$$^{miss}_{T}$ originates from weakly interacting particles, from those in which $E$$^{miss}_{T}$ is consistent with contributions coming from particle measurement, resolutions and inefficiencies. A new definition of an object-based missing transverse momentum significance variable is presented and its performance is studied in $Z$ → $ee$ and $ZZ$ → $eeνν$ events. Finally, the impact of the $S$ varaible is presented for two physics analyses using Run 2 data: Search for dark matter in association with a Higgs decaying into b-quarks Search for bottom squark production in final states containing Higgs bosons, $b$-jets and $E$$^{miss}_{T}$ and the search for direct chargino pair production with W-boson mediated decays in events with two leptons and $E$$^{miss}_{T}$.

International audience; In the past decades, short baseline neutrino oscillation studies around experimental or commercial reactor cores have revealed two anomalies. The first one is linked to the absolute flux and the second one to the spectral shape. The first anomaly, called Reactor Antineutrino Anomaly (RAA), could be explained by the introduction of a new oscillation of antineutrinos towards a sterile state of the eV mass. The STEREO detector has been taking data since the end of 2016 at 10 m from the core of the Institut Laue-Langevin research reactor, Grenoble, France. The separation of its Target volume along the neutrino propagation axis allows for measurements of the neutrino spectrum at multiple baselines, providing a clear test of an oscillation at short baseline. In this contribution, a special focus is put on the data analysis and the neutrino extraction using the Pulse Shape Discrimination observable. The results from 119 days of reactor turned on and 210 days of reactor turned off are then reported. The resulting antineutrino rate is (365.7 $\pm$ 3.2) $\bar{v}$$_{e}$/day. The test of a new oscillation towards a sterile neutrino is found to be compatible with the non-oscillation hypothesis and the best fit of the RAA is excluded at 99% C.L.