Search for pair-production of vector-like quarks in $pp$ collision events at $\sqrt{s}=13$ TeV with at least one leptonically decaying $Z$ boson and a third-generation quark with the ATLAS detector
| Popis: | A search for the pair-production of vector-like quarks optimized for decays into a $Z$ boson and a third-generation Standard Model quark is presented, using the full Run 2 dataset corresponding to 139 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV, collected in 2015-2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a $Z$ boson with high transverse momentum, reconstructed from a pair of same-flavour leptons with opposite-sign charges, as well as by the presence of $b$-tagged jets and high-transverse-momentum large-radius jets reconstructed from calibrated smaller-radius jets. Events with exactly two or at least three leptons are used, which are further categorized by the presence of boosted $W$, $Z$, and Higgs bosons and top quarks. The categorization is performed using a neural-network-based boosted object tagger to enhance the sensitivity to signal relative to the background. No significant excess above the background expectation is observed and exclusion limits at 95% confidence level are set on the masses of the vector-like partners $T$ and $B$ of the top and bottom quarks, respectively. In the singlet model, the limits allow $m_T > 1.27$ TeV and $m_B > 1.20$ TeV. In the doublet model, allowed masses are $m_T > 1.46$ TeV and $m_B >1.32$ TeV. In the case of 100% branching ratio for $T\rightarrow Zt$ and 100% branching ratio for $B\rightarrow Zb$, the limits allow $m_T > 1.60$ TeV and $m_B > 1.42$ TeV, respectively. |
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| Jazyk: | English |
| DOI: | 10.3204/pubdb-2022-06839 |
| Přístupová URL adresa: | https://explore.openaire.eu/search/publication?articleId=doi_________::0d9016930a01a01f07507f2b57dfc6c2 |
| Přírůstkové číslo: | edsair.doi...........0d9016930a01a01f07507f2b57dfc6c2 |
| Autor: | ATLAS Collaboration |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
p p: scattering
data analysis method transverse momentum: high neural network 13000 GeV-cms bottom: particle identification Higgs particle quark --> Z0 top quark: vector particle doublet final state: ((n)jet 3lepton) quark: postulated particle final state: ((n)jet dilepton) background family: 3 singlet ATLAS calibration sensitivity quark: pair production CERN LHC Coll jet: transverse momentum: high top: particle identification quark --> Z0 bottom Z0: transverse momentum Z0: leptonic decay quark: decay modes branching ratio jet: bottom p p: colliding beams quark: mass: lower limit experimental results |
| DOI: | 10.3204/pubdb-2022-06839 |
| Popis: | A search for the pair-production of vector-like quarks optimized for decays into a $Z$ boson and a third-generation Standard Model quark is presented, using the full Run 2 dataset corresponding to 139 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV, collected in 2015-2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a $Z$ boson with high transverse momentum, reconstructed from a pair of same-flavour leptons with opposite-sign charges, as well as by the presence of $b$-tagged jets and high-transverse-momentum large-radius jets reconstructed from calibrated smaller-radius jets. Events with exactly two or at least three leptons are used, which are further categorized by the presence of boosted $W$, $Z$, and Higgs bosons and top quarks. The categorization is performed using a neural-network-based boosted object tagger to enhance the sensitivity to signal relative to the background. No significant excess above the background expectation is observed and exclusion limits at 95% confidence level are set on the masses of the vector-like partners $T$ and $B$ of the top and bottom quarks, respectively. In the singlet model, the limits allow $m_T > 1.27$ TeV and $m_B > 1.20$ TeV. In the doublet model, allowed masses are $m_T > 1.46$ TeV and $m_B >1.32$ TeV. In the case of 100% branching ratio for $T\rightarrow Zt$ and 100% branching ratio for $B\rightarrow Zb$, the limits allow $m_T > 1.60$ TeV and $m_B > 1.42$ TeV, respectively. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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