Evidence for single top-quark production in the s-channel in proton–proton collisions at with the ATLAS detector using the Matrix Element Method
This Letter presents evidence for single top-quark production in the s-channel using proton-proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The analysis is performed on events containing one isolated electron or muon, large missing transverse momentum and exactly t wo b-tagged jets in the final state. The analysed data set corresponds to an integrated luminosity of 20.3 fb -1 . The signal is extracted using a maximum-likelihood fit of a discriminant which is based on the matrix element method and optimized in order to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W boson production in association with heavy-flavour jets. The measurement leads to an observed signal significance of 3.2 standard deviations and a measured cross-section of σs=4.8±0.8(stat.)-1.3+1.6(syst.) pb, which is consistent with the Standard Model expectation. The expected significance for the analysis is 3.9 standard deviations.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- ATLAS Collaboration
- Grant/Contract Number:
- AC02-76SF00515; AC02-05CH11231
- OSTI ID:
- 1241427
- Alternate ID(s):
- OSTI ID: 1242386; OSTI ID: 1379336
- Journal Information:
- Physics Letters B, Journal Name: Physics Letters B Vol. 756 Journal Issue: C; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
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