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Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at √s=8 TeV using the ATLAS experiment

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  • ATLAS Collaboration
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Article number407
<mark>Journal publication date</mark>3/09/2015
<mark>Journal</mark>European Physical Journal C: Particles and Fields
Issue number9
Volume75
Number of pages25
<mark>State</mark>Published
<mark>Original language</mark>English

Abstract

Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of 18.4 fb−1 of pp collisions at √s = 8 TeV. No signifi- cant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on Rhadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 % confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.