91 research outputs found

    Simulations and Data analysis for the 35 ton Liquid Argon detector as a prototype for the DUNE experiment

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    The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment which will be built at the Sanford Underground Research Facility (SURF), and will receive a wide-band neutrino beam from Fermilab, 1300 km away. At this baseline DUNE will be able to study many of the properties of neutrino mixing, including the neutrino mass hierarchy and the value of the CP-violating complex phase (őīCP). DUNE will utilise Liquid Argon (LAr) Time Projection Chamber (TPC) (LArTPC) technology, and the Far Detector (FD) will consist of four modules, each containing 17.1 kt of LAr with a fiducial mass of around 10 kt. Each of these FD modules represents around an order of magnitude increase in size, when compared to existing LArTPC experiments. The 35 ton detector is the first DUNE prototype for the single (LAr) phase design of the FD. There were two running periods, one from November 2013 to February 2014, and a second from November 2015 to March 2016. During the second running period, a system of TPCs was installed, and cosmic-ray data were collected. A method of particle identification was developed using simulations, though this was not applied to the data due to the higher than expected noise level. A new method of determining the interaction time of a track, using the effects of longitudinal diffusion, was developed using the cosmic-ray data. A camera system was also installed in the detector for monitoring purposes, and to look for high voltage breakdowns. Simulations concerning the muon-induced background rate to nucleon decay are performed, following the incorporation of the MUon Simulations UNderground (MUSUN) generator into the DUNE software framework. A series of cuts which are based on Monte Carlo truth information is developed, designed to reject simulated background events, whilst preserving simulated signal events in the n‚ÜíK++e‚ąí decay channel. No background events are seen to survive the application of these cuts in a sample of 2 √ó 109 muons, representing 401.6 years of detector live time. This corresponds to an annual background rate of < 0.44 events¬∑Mt‚ąí1¬∑year‚ąí1 at 90% confidence, using a fiducial mass of 13.8 kt

    Erratum to: Combined analysis of Belle and Belle II data to determine the CKM angle Ōē3 using B+ ‚Üí D(K0Sh+h‚ąí)h+ decays

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    Search for dark matter produced in association with bottom or top quarks in ‚ąös = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb‚ąí1 of proton‚Äďproton collision data recorded by the ATLAS experiment at ‚ąös = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Measurement of the branching fraction and CP\it CP asymmetry of B0‚ÜíŌÄ0ŌÄ0B^{0} \rightarrow \pi^{0} \pi^{0} decays using 198√ó106198 \times 10^6 BB‚ÄĺB\overline{B} pairs in Belle II data

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    We report measurements of the branching fraction and CP\it CP asymmetry in B0‚ÜíŌÄ0ŌÄ0B^{0} \to \pi^{0} \pi^{0} decays reconstructed at Belle II in an electron-positron collision sample containing 198√ó106198 \times 10^{6} BB‚ÄĺB\overline{B} pairs. We measure a branching fraction \mathcal{B}(\Bpipi) = (1.38 \pm 0.27 \pm 0.22) \times 10^{-6} and a CP\it CP asymmetry \Acp(\Bpipi) = 0.14 \pm 0.46 \pm 0.07, where the first uncertainty is statistical and the second is systematic

    Measurements of the branching fractions for B‚ÜíK‚ąóő≥B \to K^{*}\gamma decays at Belle II