Search for a Higgs Portal scalar boson decaying to e+e- in MicroBooNE Pawel Guzowski (The University of Manchester) on behalf of the MicroBooNE collaboration The Higgs Portal model Production and decay of scalars Neutrino portal mixing of ν-N `, ⇡ New dark sector scalar S mixes with the Higgs boson Decay in detector Can be produced in kaon decays via penguin diagram ν (neutrinos) N? `, ⇡ Production in Scalars travel a macroscopic distance – hundreds of meters S acquires coupling to the Standard Model fermions Standard Vector portal Dark …? S Xµ? neutrino beamlines Model mixing Aµ-Xµ Sector? Decay to electron-positron pairs (for masses below the via the Higgs Yukawa coupling Aµ (photons) s d H (Higgs) di-muon threshold) S? K W c, t ⇡ Two model parameters: mixing angle θ, and scalar mass Higgs portal q q More info in Batell, Berger, Ismail, Phys Rev D 100, 115039 (2019) mixing H-S Signature of Higgs Portal scalars in MicroBooNE We utilize kaons decaying at rest in the NuMI hadron absorber (stops remnant protons & mesons in beamline) Aerial view of MicroBooNE Scalars coming from direction of hadron MicroBooNE: liquid argon absorber have an ‘opposite’ direction to typical time projection chamber µBooNE neutrino interactions in MicroBooNE mm-scale position resolution scalars Search for large-opening-angle events pointing towards the absorber NuMI beam: (arXiv 1507.06690) Reconstruction and selection Results 10 8 MicroBooNE Preliminary 10 MicroBooNE Preliminary 10 20 20 Run 1, NuMI FHC 0.92´10 POT 109 Run 1, NuMI FHC 0.92´10 POT 107 Counts / 1 Off-beam data Dirt n simulation Counts / 1 108 Off-beam data Dirt n simulation 106 We are using only 8% of the available NuMI Cosmic Cryo. n simulation 107 Cosmic Cryo. n simulation We observe 5 events in signal region after BDT cuts, 5 10 6 On-beam data 150 MeV/c2 signal 10 On-beam data 150 MeV/c2 signal 4 dataset for this first search 10 105 consistent with background expectation of 2.0±0.8 103 104 2 3 Run 1 Run 10 10 ➤ All 5 are visually consistent with backgrounds, e.g. 2 10 10 -3 Using Pandora reconstruction, search for pairs 10 10 1 stopping muons with decay electrons; three-prong 1 10-1 of reconstructed objects 10-1 10-2 neutrino interactions; photon+proton production 10-2 -20 -15 -10 -5 0 5 10 15 20 -20 -15 -10 -5 0 5 10 15 20 BDText score BDTnu score 0.5 0.5 0.4 0.4 Geometrical based selection e.g. angles, lengths 0.3 0.3 2 0.2 0.2 0.1 0.1 We set a competitive limit in the 120—160 MeV/c 0 0 -0.1 -0.1 -0.2 -0.2 -0.3 -0.3 q (obs-pred)/pred – no calorimetric or PID info used for this first -0.4 (obs-pred)/pred -0.4 -0.5 -0.5 scalar mass range BDT score vs cosmics BDT score vs neutrinos MicroBooNE Preliminary 95% CL limit analysis 107 MicroBooNE Preliminary MicroBooNE Preliminary 6 Run 3, NuMI RHC 1.01´1020 POT 10 Run 3, NuMI RHC 1.01´1020 POT 6 Counts / 1 10 Counts / 1 Off-beam data Dirt n simulation 5 10 Off-beam data Dirt n simulation KOTO ±1s allowed region We can exclude at 95%CL the remaining central value 105 Cosmic Cryo. n simulation Cosmic Cryo. n simulation Four Boosted Decision Trees trained to 2 4 10 2 4 On-beam data 150 MeV/c signal 10 On-beam data 150 MeV/c signal -4 model parameters required to explain the KOTO 103 10 CHARM limit 3 0 discriminate signal decays from background 10 anomalous excess of K →π +invisible decays 2 L 2 10 (cosmic or neutrino) across two run periods 3 Run 10 E949 limit 10 10 1 1 More info: MICROBOONE-NOTE-1092-PUB (’Run 1’ and ‘Run 3’) NA62 limit 10-1 10-1 -20 -15 -10 -5 0 5 10 15 20 -20 -15 -10 -5 0 5 10 15 20 See also the ICHEP talk: YouTube link (@4h30m) BDText score BDTnu score Two-dimensional BDT cuts are chosen to 0.5 0.5 100 110 120 130 140 150 160 170 180 190 200 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 2 -0.1 -0.1 maximize sensitivity -0.2 -0.2 Scalar mass (MeV/c ) -0.3 -0.3 (obs-pred)/pred -0.4 (obs-pred)/pred -0.4 -0.5 -0.5 2 This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 752309.