${{\mathit t}}{{\overline{\mathit t}}}$ ${{\mathit t}}{{\overline{\mathit t}}}$ Production Cross Section in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 13 TeV

INSPIRE  
VALUE (fb) CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$26$ ${}^{+17}_{-15}$ 1
AAD
2021BC
ATLS ${{\mathit \ell}}$ or ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ + jets
$24$ ${}^{+7}_{-6}$ 2
AAD
2021BC
ATLS combination of 1${{\mathit \ell}}$ /2${{\mathit \ell}}$ (OS) and 2${{\mathit \ell}}$ (SS)/3${{\mathit \ell}}$
$24$ ${}^{+7}_{-6}$ 3
AAD
2020AR
ATLS (same-sign 2${{\mathit \ell}}$ ) or ${}\geq{}3{{\mathit \ell}}$ + jets
$12.6$ ${}^{+5.8}_{-5.2}$ 4
SIRUNYAN
2020C
CMS (same-sign 2${{\mathit \ell}}$ ) or 3${{\mathit \ell}}$ + jets
$<47$ 95 5
AABOUD
2019AP
ATLS ${{\mathit \ell}}$ + ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ channels
$<49$ 95 6
AABOUD
2019AP
ATLS combination of ATLAS
$13$ ${}^{+11}_{-9}$ 7
SIRUNYAN
2019CN
CMS combination of CMS
$<48$ 95 8
SIRUNYAN
2019CN
CMS ${{\mathit \ell}}$ +jets, ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ +jets channels
$<69$ 95 9
AABOUD
2018CE
ATLS ${}\geq{}2{{\mathit \ell}}$ (same sign) + $\not E_T$ + ${}\geq{}1{{\mathit b}}$ j
$16.9$ ${}^{+13.8}_{-11.4}$ 10
SIRUNYAN
2018BU
CMS ${{\mathit t}}$ ${{\overline{\mathit t}}}$ ${{\mathit t}}$ ${{\overline{\mathit t}}}$ $\rightarrow$ (same sign 2${{\mathit \ell}}$ or ${}\geq{}3{{\mathit \ell}}$ ) + ${}\geq{}$4 j (${}\geq{}2{{\mathit b}}$ )
$<94$ 95 11
SIRUNYAN
2017AB
CMS ${{\mathit \ell}}$ +jets, ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ +jets channels
$<42$ 95 12
SIRUNYAN
2017S
CMS (same sign 2${{\mathit \ell}}$ )+$\not E_T+{}\geq{}$2j
1  AAD 2021BC result is based on 139 fb${}^{-1}$ of data. The events are categorized according to the number of jets and how likely to contain ${{\mathit b}}$ -hadrons and a multivariate analysis is used to discriminate the signal from backgrounds. The result corresponds to observed significance of 1.9 $\sigma $.
2  AAD 2021BC combines the results of the four-top-quark production cross section measured from the 1${{\mathit \ell}}$ /opposite-sign 2${{\mathit \ell}}$ channel with that from the same-sign 2${{\mathit \ell}}$ /3${{\mathit \ell}}$ channel (AAD 2020AR). The result corresponds to observed significance of 4.7 $\sigma $ and is consistent within 2.0 $\sigma $ with the NLO (QCD+EW) SM prediction of $12.0$ $\pm2.4$ fb.
3  AAD 2020AR based on 139 fb${}^{-1}$ of data. Jet multiplicity, jet flavor and event kinematics are used in a multivariate analysis to discriminate the signal from backgrounds. The result corresponds to observed significance of 4.3$\sigma $ and is consistent within 1.7$\sigma $ with the NLO (QCD+EW) SM prediction of $12.0$ $\pm2.4$ fb.
4  SIRUNYAN 2020C based on 137 fb${}^{-1}$ of data. Both cut-based and multivariate approaches are taken to discriminate the signal from backgrounds. The result is in agreement with the NLO (QCD+EW) SM prediction of $12.0$ ${}^{+2.2}_{-2.5}$ fb. The measurement constrains the top quark Yukawa coupling strength parameter to be $\vert {{\mathit Y}_{{t}}}$ /${{\mathit Y}_{{t}}^{SM}}$ $\vert $ $<$ 1.7 (95$\%$ CL). It is also used to constrain an oblique parameter of the Higgs boson.
5  AABOUD 2019AP based on 36.1 fb${}^{-1}$ of data. The upper limit corresponds to 5.1 times the NLO SM cross section.
6  AABOUD 2019AP limit from data combined with AABOUD 2018CE. The upper limit corresponds to 5.3 times the NLO SM cross section. Also a limit on the four-top-quark contact interaction of $\vert \mathit C_{4t}\vert /\Lambda {}^{2}$ $<$ 1.9 TeV${}^{-2}$ (95$\%$ CL) is obtained in an EFT model.
7  SIRUNYAN 2019CN based on 35.8 fb${}^{-1}$ of data, combined with SIRUNYAN 2018BU. The results are also interpreted in the effective field theory framework.
8  SIRUNYAN 2019CN based on 35.8 fb${}^{-1}$ of data. A multivariate analysis using global event and jet propoerties is performed to discriminate from ${{\mathit t}}{{\overline{\mathit t}}}$ background.
9  AABOUD 2018CE based on 36.1 fb${}^{-1}$ of proton-proton data taken at $\sqrt {s }$ = 13 TeV. Events including a same-sign lepton pair are used. The result is consistent with the NLO SM cross section of 9.2 fb.
10  SIRUNYAN 2018BU based on 35.9 fb${}^{-1}$ of proton-proton data taken at $\sqrt {s }$ = 13 TeV. Yields from signal regions and control regions defined based on ${{\mathit N}_{{jets}}}$ , ${{\mathit N}_{{b}}}$ and ${{\mathit N}_{{l}}}$ are combined in a maximum-likelihood fit. The result is in agreement with the NLO SM prediction $9.2$ ${}^{+2.9}_{-2.4}$ fb. The measurement constrains the top quark Yukawa coupling strength parameter to be $\vert \mathit Y_{t}/\mathit Y{}^{SM}_{t}\vert $ $<$ 2.1 (95$\%$ CL).
11  SIRUNYAN 2017AB based on 2.6 fb${}^{-1}$ of data. A multivariate analysis is used to discriminate between ${{\mathit t}}{{\overline{\mathit t}}}{{\mathit t}}{{\overline{\mathit t}}}$ signal and ${{\mathit t}}{{\overline{\mathit t}}}$ background. A combination with a previous search (CMS, KHACHATRYAN 2016BJ) in the same-sign dilepton channel gives an upper limit of 69 fb (95$\%$ CL), corresponding to 7.4$\cdot{}$(SM prediction).
12  SIRUNYAN 2017S based on 35.9 fb${}^{-1}$. The limit is in agreement with the NLO SM prediction $9.2$ ${}^{+2.9}_{-2.4}$ fb. Superseded by SIRUNYAN 2018BU. The signal events are also used to constrain various new physics models.
References:
AAD 2021BC
JHEP 2111 118
AAD 2020AR
EPJ C80 1085 Evidence for $t\bar{t}t\bar{t}$ production in the multilepton final state in proton?proton collisions at $\sqrt{s}=13$ $\text {TeV}$ with the ATLAS detector
SIRUNYAN 2020C
EPJ C80 75 Search for production of four top quarks in final states with same-sign or multiple leptons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
AABOUD 2019AP
PR D99 052009 Search for four-top-quark production in the single-lepton and opposite-sign dilepton final states in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector
SIRUNYAN 2019CN
JHEP 1911 082 Search for the production of four top quarks in the single-lepton and opposite-sign dilepton final states in proton-proton collisions at $ \sqrt{s} $ = 13 TeV
AABOUD 2018CE
JHEP 1812 039 Search for new phenomena in events with same-charge leptons and $b$-jets in $pp$ collisions at $\sqrt{s}= 13$ TeV with the ATLAS detector
SIRUNYAN 2018BU
EPJ C78 140 Search for standard model production of four top quarks with same-sign and multilepton final states in proton?proton collisions at $\sqrt{s} = 13\,\text {TeV} $
SIRUNYAN 2017AB
PL B772 336 Search for Standard Model Production of Four Top Quarks in Proton-Proton Collisions at $\sqrt {s }$ = 13 TeV
SIRUNYAN 2017S
EPJ C77 578 Search for Physics beyond the Standard Model in Events with Two Leptons of Same Sign, Missing Transverse Momentum, and Jets in Proton-Proton Collisions at $\sqrt {s }$ = 13 TeV