Search For Neutral Long Lived Particles In Pp Collisions At Square Roots
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Author | : [Study Group] ATLAS Collaboration CERN |
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Total Pages | : 0 |
Release | : 2022 |
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Abstract: A search for decays of pair-produced neutral long-lived particles (LLPs) is presented using 139 fb−1 of proton-proton collision data collected by the ATLAS detector at the LHC in 2015-2018 at a centre-of-mass energy of 13 TeV. Dedicated techniques were developed for the reconstruction of displaced jets produced by LLPs decaying hadronically in the ATLAS hadronic calorimeter. Two search regions are defined for different LLP kinematic regimes. The observed numbers of events are consistent with the expected background, and limits for several benchmark signals are determined. For a SM Higgs boson with a mass of 125 GeV, branching ratios above 10% are excluded at 95% confidence level for values of c times LLP mean proper lifetime in the range between 20 mm and 10 m depending on the model. Upper limits are also set on the cross-section times branching ratio for scalars with a mass of 60 GeV and for masses between 200 GeV and 1 TeV
Author | : Rachel Rosten |
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Total Pages | : 180 |
Release | : 2017 |
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A search for the decay of a heavy scalar boson into pairs of long-lived neutral particles in \intlumi of proton proton collisions at $\sqrt{s}=8$~TeV and $3.2~\rm{fb}^{-1}$ at $\sqrt{s}=13$~TeV in the ATLAS detector is presented. The search focuses on final states where both long lived particles decay within the hadronic calorimeter of the detector, resulting in jets with unusual properties. No excess was observed and limits were set on the lifetime of the long lived particles for various combinations of scalar boson and long lived particle masses.
Author | : [Study Group] ATLAS Collaboration CERN |
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Total Pages | : 0 |
Release | : 2022 |
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Abstract: A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139 fb−1 of proton-proton collision data at √s=13 TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into t ̄t in the ATLAS muon spectrometer
Author | : Siinn Che |
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Total Pages | : 92 |
Release | : 2018 |
Genre | : Dilepton production |
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Total Pages | : 852 |
Release | : 1990 |
Genre | : Power resources |
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Author | : Peter Wagner |
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Total Pages | : |
Release | : 2010 |
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This dissertation presents the results of the first search for heavy, neutral, longlived particles that decay to photons at a hadron collider. We use a sample of +jet+missing transverse energy events in pp̄ collisions at s = 1.96 TEV taken with the Collider Detector at Fermilab. Candidate events are selected based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed. The final result is that we find 2 events, using 570"34 pb−1 of data collected during 2004-2005 at the Fermilab Tevatron, consistent with the background estimate of 1.3"0.7 events.
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Total Pages | : 149 |
Release | : 2009 |
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The existence of the Higgs boson is required by the Standard Model of particle physics, yet it has not been observed. The precise nature of the Higgs boson is unknown and the mechanism by which it interacts with known Standard Model particles is also not known. Long-lived, electrically neutral hadrons have recently been proposed in hidden-valley models and could constitute a pathway through which the Higgs boson communicates with the Standard Model. Such a scenario may provide a novel path to Higgs discovery at the Tevatron. This thesis describes a search for a neutral, long-lived particle produced in decays of Higgs bosons in p{bar p} collisions at a center-of-mass energy of (square root)s = 1.96 TeV, which decays to b-jets and lives long enough to travel at least 1.6 cm before decaying. This analysis uses 3.65 fb−1 of data recorded with the Run II D0 detector at the Fermilab Tevatron collider from April 2002 to August of 2008. We perform a search for eight possible hidden-valley scenarios resulting from a Higgs decay. No significant excess over background is observed and cross-section limits are placed at 95% CL.
Author | : Rachel Paula Yohay |
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Release | : 2012 |
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Author | : Shikma Bressler |
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Total Pages | : 59 |
Release | : 2011 |
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Author | : Martina Javůrková |
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Total Pages | : |
Release | : 2017 |
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