Publication
Search for flavour-changing neutral current top quark decays $t\to Hq$ in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
| dc.contributor.author | ATLAS collaboration (2865 authors) | |
| dc.contributor.author | Aguilar-Saavedra, Juan Antonio | |
| dc.contributor.author | Amor Dos Santos, Susana Patricia | |
| dc.contributor.author | Anjos, Nuno | |
| dc.contributor.author | Araque, Juan Pedro | |
| dc.contributor.author | Cantrill, Robert | |
| dc.contributor.author | Carvalho, João | |
| dc.contributor.author | Castro, Nuno Filipe | |
| dc.contributor.author | Conde Muiño, Patricia | |
| dc.contributor.author | Da Cunha Sargedas De Sousa, Mario Jose | |
| dc.contributor.author | Fiolhais, Miguel | |
| dc.contributor.author | Galhardo, Bruno | |
| dc.contributor.author | Gomes, Agostinho | |
| dc.contributor.author | Gonçalo, Ricardo | |
| dc.contributor.author | Jorge, Pedro | |
| dc.contributor.author | Lopes, Lourenco | |
| dc.contributor.author | Machado Miguens, Joana | |
| dc.contributor.author | Maio, Amélia | |
| dc.contributor.author | Maneira, José | |
| dc.contributor.author | Onofre, António | |
| dc.contributor.author | Palma, Alberto | |
| dc.contributor.author | Pedro, Rute | |
| dc.contributor.author | Pina, João Antonio | |
| dc.contributor.author | Santos, Helena | |
| dc.contributor.author | Saraiva, João | |
| dc.contributor.author | Silva, José | |
| dc.contributor.author | Tavares Delgado, Ademar | |
| dc.contributor.author | Veloso, Filipe | |
| dc.contributor.author | Wolters, Helmut | |
| dc.date.accessioned | 2019-02-04T08:10:04Z | |
| dc.date.available | 2019-02-04T08:10:04Z | |
| dc.date.issued | 2015-12-10 | |
| dc.date.updated | 2019-02-04T08:10:04Z | |
| dc.description.abstract | A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to $ b\overline{b} $ , is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at $ \sqrt{s}=8 $ TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb$^{−1}$. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by $ t\overline{t}\to WbWb $ decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW$^{*}$, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ$_{tcH}$ | and |λ$_{tuH}$ | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on tqH interactions measured so far. | |
| dc.description.version | Peer Reviewed | |
| dc.identifier | JHEP 1512 (2015) 061; DOI 10.1007/JHEP12(2015)061 | |
| dc.identifier.uri | http://dx.doi.org/10.1007/JHEP12(2015)061 | |
| dc.identifier.uri | http://hdl.handle.net/10400.26/26936 | |
| dc.language.iso | eng | |
| dc.title | Search for flavour-changing neutral current top quark decays $t\to Hq$ in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector | |
| dc.type | journal article | |
| dspace.entity.type | Publication | |
| rcaap.rights | openAccess | pt |
| rcaap.type | article |