#### ${{\mathit b}^{\,'}}$ ($-1$/3)-quark/hadron mass limits in ${{\mathit p}}{{\overline{\mathit p}}}$ and ${{\mathit p}}{{\mathit p}}$ collisions

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{> 1570}$ 95 1
 2020 BI
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$ ) = 1
$\bf{> 1390}$ 95 1
 2020 BI
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$> 1130$ 95 2
 2019 AQ
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$>1230$ 95 3
 2019 BW
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$\bf{> 1350}$ 95 4
 2018 AW
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 1000$ 95 5
 2018 CE
ATLS ${}\geq{}2{{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}1{{\mathit b}}$ j
$> 950$ 95 6
 2018 CL
ATLS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 1010$ 95 7, 8
 2018 CP
ATLS 2,3${{\mathit \ell}}$ , singlet model
$> 1140$ 95 6, 9
 2018 CP
ATLS 2,3${{\mathit \ell}}$ , doublet model
$> 1220$ 95 10, 11
 2018 CR
ATLS singlet ${{\mathit b}^{\,'}}$ . ATLAS Combination
$> 1370$ 95 10, 12
 2018 CR
ATLS ${{\mathit b}^{\,'}}$ in a weak isospin doublet (${{\mathit t}^{\,'}}$ ,${{\mathit b}^{\,'}}$ ). ATLAS combination.
$> 910$ 95 13
 2018 BM
CMS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 845$ 95 14
 2018 Q
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit u}}$ ) = 1
$> 730$ 95 15
 2017 AU
CMS
$> 880$ 95 16
 2016 AN
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 620$ 95 17
 2015 BY
ATLS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 730$ 95 18
 2015 BY
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 810$ 95 19
 2015 Z
ATLS
$> 755$ 95 20
 2014 AZ
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 675$ 95 21
 2013 I
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$\bf{> 190}$ 95 22
 2008 X
D0 c = 200mm
$\bf{> 190}$ 95 23
 2003
CDF quasi-stable ${{\mathit b}^{\,'}}$
• • We do not use the following data for averages, fits, limits, etc. • •
$\text{<350, 580 - 635, >700}$ 95 24
 2015 AR
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$ ) = 1
$> 690$ 95 25
 2015 CN
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$ ) = 1 (${{\mathit q}}$ =${{\mathit u}}$ )
$> 480$ 95 26
 2012 AT
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 400$ 95 27
 2012 AU
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$> 350$ 95 28
 2012 BC
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$ ) = 1 (${{\mathit q}}$ =${{\mathit u}}$ ,${{\mathit c}}$ )
$> 450$ 95 29
 2012 BE
ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 685$ 95 30
 2012 BH
CMS ${\mathit m}_{{{\mathit t}^{\,'}}}$ = ${\mathit m}_{{{\mathit b}^{\,'}}}$
$> 611$ 95 31
 2012 X
CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 372$ 95 32
 2011 J
CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$> 361$ 95 33
 2011 L
CMS Repl. by CHATRCHYAN 2012X
$> 338$ 95 34
 2010 H
CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$\text{>380 - 430}$ 95 35
 2010
RVUE ${\mathit m}_{{{\mathit b}^{\,'}}}>$ ${\mathit m}_{{{\mathit t}^{\,'}}}$
$> 268$ 95 36, 37
 2007 C
CDF B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ) = 1
$>199$ 95 38
 2000
CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$
$>148$ 95 39
 1998 N
CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ + vertex
$>96$ 95 40
 1997 D
D0 NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$
$>128$ 95 41
 1995 F
D0 ${{\mathit \ell}}{{\mathit \ell}}$ $+$ jets, ${{\mathit \ell}}$ $+$ jets
$>75$ 95 42
 1993
RVUE NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \ell}}{{\mathit \ell}}$
$>85$ 95 43
 1992
CDF CC: ${{\mathit \ell}}{{\mathit \ell}}$
$>72$ 95 44
 1990 B
CDF CC: ${{\mathit e}}$ $+$ ${{\mathit \mu}}$
$>54$ 95 45
 1990
UA2 CC: ${{\mathit e}}$ $+$ jets + $\not E_T$
$>43$ 95 46
 1990 B
UA1 CC: ${{\mathit \mu}}$ $+$ jets
$>34$ 95 47
 1988
UA1 CC: ${{\mathit e}}$ or ${{\mathit \mu}}$ + jets
 1 SIRUNYAN 2020BI based on 137 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair production of vector-like ${{\mathit b}^{\,'}}$ is seached for with each ${{\mathit b}^{\,'}}$ decaying into ${{\mathit Z}}{{\mathit b}}$ or ${{\mathit h}}{{\mathit b}}$ . Analysis focuses on final states consisting of jets from six quarks. Mass limits are obtained for a variety of branching ratios of ${{\mathit b}^{\,'}}$ decays.
 2 SIRUNYAN 2019AQ based on 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair production of vector-like ${{\mathit b}^{\,'}}$ is seached for with one ${{\mathit b}^{\,'}}$ decaying into ${{\mathit Z}}{{\mathit b}}$ and the other ${{\mathit b}^{\,'}}$ decaying into ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ . Events with an opposite-sign lepton pair consistent with coming from ${{\mathit Z}}$ and jets are used. Mass limits are obtained for a variety of branching ratios of ${{\mathit b}^{\,'}}$ .
 3 SIRUNYAN 2019BW based on 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. The limit is for the pair-produced vector-like ${{\mathit b}^{\,'}}$ using all-hadronic final state. The analysis is made for the ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit W}}{{\mathit t}}$ , ${{\mathit h}}{{\mathit b}}$ modes and mass limits are obtained for a variety of branching ratios.
 4 AABOUD 2018AW based on 36.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. The limit is for the pair-produced vector-like ${{\mathit b}^{\,'}}$ using lepton-plus-jets final state. The search is also sensitive to the decays into ${{\mathit Z}}{{\mathit b}}$ and ${{\mathit H}}{{\mathit b}}$ final states.
 5 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 limit is for a singlet model, assuming the branching ratios of ${{\mathit b}^{\,'}}$ into ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit W}}{{\mathit t}}$ and ${{\mathit H}}{{\mathit b}}$ as predicted by the model.
 6 AABOUD 2018CL, AABOUD 2018CP based on 36.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. The limit is for the pair-produced vector-like ${{\mathit b}^{\,'}}$ using all-hadronic final state. The analysis is particularly powerful for the ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit h}}{{\mathit b}}$ mode. Assuming the pure decay only in this mode sets a limit ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 1010 GeV.
 7 AABOUD 2018CP based on 36.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair and single production of vector-like ${{\mathit b}^{\,'}}$ are seached for with at least one ${{\mathit b}^{\,'}}$ decaying into ${{\mathit Z}}{{\mathit b}}$ . In the case of B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1, the limit is ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 1220 GeV.
 8 The limit is for the singlet model, assuming that the branching ratios into ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ add up to one.
 9 The limit is for the doublet model, assuming that the branching ratios into ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ add up to one.
 10 AABOUD 2018CR based on 36.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. A combination of searches for the pair-produced vector-like ${{\mathit b}^{\,'}}$ in various decay channels ( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ ). Also a model-independent limit is obtained as ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 1.03 TeV, assuming that the branching ratios into ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit W}}{{\mathit t}}$ , and ${{\mathit h}}{{\mathit b}}$ add up to one.
 11 The limit is for the singlet ${{\mathit b}^{\,'}}$ .
 12 The limit is for ${{\mathit b}^{\,'}}$ in a weak isospin doublet (${{\mathit t}^{\,'}}$ ,${{\mathit b}^{\,'}}$ ) and $\vert {{\mathit V}}$ $_{{{\mathit t}^{\,'}} {{\mathit b}} }\vert$ ${}\ll$ $\vert {{\mathit V}}$ $_{{{\mathit t}} {{\mathit b}^{\,'}} }\vert$. For a ${{\mathit b}^{\,'}}$ in a doublet with a charge $−$4/3 vector-like quark, the limit ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 1.14 TeV is obtained.
 13 SIRUNYAN 2018BM based on 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. The limit is for the pair-produced vector-like ${{\mathit b}^{\,'}}$ . Three channels (single lepton, same-charge 2 leptons, or at least 3 leptons) are considered for various branching fraction combinations. Assuming B( ${{\mathit t}}{{\mathit W}}$ ) = 1, the limit is 1240 GeV and for B( ${{\mathit b}}{{\mathit Z}}$ ) = 1 it is 960 GeV.
 14 SIRUNYAN 2018Q based on 19.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. The limit is for the pair-produced vector-like ${{\mathit b}^{\,'}}$ that couple only to light quarks. Upper cross section limits on the single production of a ${{\mathit b}^{\,'}}$ and constraints for other decay channels ( ${{\mathit Z}}{{\mathit q}}$ and ${{\mathit H}}{{\mathit q}}$ ) are also given in the paper.
 15 SIRUNYAN 2017AU based on $2.3 - 2.6$ fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Limit on pair-produced singlet vector-like ${{\mathit b}^{\,'}}$ using one lepton and several jets. The mass bound is given for a ${{\mathit b}^{\,'}}$ transforming as a singlet under the electroweak symmetry group, assumed to decay through ${{\mathit W}}$ , ${{\mathit Z}}$ or Higgs boson (which decays to jets) and to a third generation quark.
 16 KHACHATRYAN 2016AN based on 19.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Limit on pair-produced vector-like ${{\mathit b}^{\,'}}$ using 1, 2, and $>$2 leptons as well as fully hadronic final states. Other limits depending on the branching fractions to ${{\mathit t}}{{\mathit W}}$ , ${{\mathit b}}{{\mathit Z}}$ , and ${{\mathit b}}{{\mathit H}}$ are given in Table IX.
 17 AAD 2015BY based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Limit on pair-produced vector-like ${{\mathit b}^{\,'}}$ assuming the branching fractions to ${{\mathit W}}$ , ${{\mathit Z}}$ , and ${{\mathit h}}$ modes of the singlet model. Used events containing ${}\geq{}2{{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$2j (${}\geq{}$1 ${{\mathit b}}$ ) and including a same-sign lepton pair.
 18 AAD 2015BY based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Limit on pair-produced chiral ${{\mathit b}^{\,'}}$ -quark. Used events containing ${}\geq{}2{{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$2j (${}\geq{}$1 ${{\mathit b}}$ ) and including a same-sign lepton pair.
 19 AAD 2015Z based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Used events with ${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$6j (${}\geq{}$1 ${{\mathit b}}$ ) and at least one pair of jets from weak boson decay, primarily designed to select the signature ${{\mathit b}^{\,'}}$ ${{\overline{\mathit b}}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit W}}{{\mathit t}}{{\overline{\mathit t}}}$ $\rightarrow$ ${{\mathit W}}{{\mathit W}}{{\mathit W}}{{\mathit W}}{{\mathit b}}{{\overline{\mathit b}}}$ . This is a limit on pair-produced vector-like ${{\mathit b}^{\,'}}$ . The lower mass limit is 640 GeV for a vector-like singlet ${{\mathit b}^{\,'}}$ .
 20 Based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. No significant excess over SM expectation is found in the search for pair production or single production of ${{\mathit b}^{\,'}}$ in the events with dilepton from a high $p_T$ ${{\mathit Z}}$ and additional jets (${}\geq{}$ 1 ${{\mathit b}}$ -tag). If instead of B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1 an electroweak singlet with B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) $\sim{}$ 0.45 is assumed, the limit reduces to 685 GeV.
 21 Based on 5.0 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. CHATRCHYAN 2013I looked for events with one isolated electron or muon, large $\not E_T$, and at least four jets with large transverse momenta, where one jet is likely to originate from the decay of a bottom quark.
 22 Result is based on 1.1 fb${}^{-1}$ of data. No signal is found for the search of long-lived particles which decay into final states with two electrons or photons, and upper bound on the cross section times branching fraction is obtained for 2 $<$ c $<$ 7000 mm; see Fig. 3. 95$\%$ CL excluded region of ${{\mathit b}^{\,'}}$ lifetime and mass is shown in Fig. 4.
 23 ACOSTA 2003 looked for long-lived fourth generation quarks in the data sample of 90 pb${}^{-1}$ of $\sqrt {\mathit s }$=1.8 TeV ${{\mathit p}}{{\overline{\mathit p}}}$ collisions by using the muon-like penetration and anomalously high ionization energy loss signature. The corresponding lower mass bound for the charge (2/3)e quark (${{\mathit t}^{\,'}}$ ) is 220 GeV. The ${{\mathit t}^{\,'}}$ bound is higher than the ${{\mathit b}^{\,'}}$ bound because ${{\mathit t}^{\,'}}$ is more likely to produce charged hadrons than ${{\mathit b}^{\,'}}$ . The 95$\%$ CL upper bounds for the production cross sections are given in their Fig.$~$3.
 24 AAD 2015AR based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Used lepton-plus-jets final state. See Fig. 24 for mass limits in the plane of B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) vs. B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$ ) from ${{\mathit b}^{\,'}}$ ${{\overline{\mathit b}}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}{+}$ ${{\mathit X}}$ searches.
 25 AAD 2015CN based on 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 8 TeV. Limit on pair-production of chiral ${{\mathit b}^{\,'}}$ -quark. Used events with ${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$4j (non-${{\mathit b}}$ -tagged). Limits on a heavy vector-like quark, which decays into ${{\mathit W}}$ ${{\mathit q}}$ , ${{\mathit Z}}{{\mathit q}}$ , ${{\mathit h}}{{\mathit q}}$ , are presented in the plane B( ${{\mathit Q}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$ ) vs. B( ${{\mathit Q}}$ $\rightarrow$ ${{\mathit h}}{{\mathit q}}$ ) in Fig. 12.
 26 Based on 1.04 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. No signal is found for the search of heavy quark pair production that decay into ${{\mathit W}}$ and a ${{\mathit t}}$ quark in the events with a high $p_T$ isolated lepton, large $\not E_T$, and at least 6 jets in which one, two or more dijets are from ${{\mathit W}}$ .
 27 Based on 2.0 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. No ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ invariant mass peak is found in the search of heavy quark pair production that decay into ${{\mathit Z}}$ and a ${{\mathit b}}$ quark in events with ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ and at least one ${{\mathit b}}$ -jet. The lower mass limit is 358 GeV for a vector-like singlet ${{\mathit b}^{\,'}}$ mixing solely with the third SM generation.
 28 Based on 1.04 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. No signal is found for the search of heavy quark pair production that decay into ${{\mathit W}}$ and a quark in the events with dileptons, large $\not E_T$, and ${}\geq{}$2 jets.
 29 Based on 1.04 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. AAD 2012BE looked for events with two isolated like-sign leptons and at least 2 jets, large $\not E_T$ and H$_{T}$ $>$ 350 GeV.
 30 Based on 5 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. CHATRCHYAN 2012BH searched for QCD and EW production of single and pair of degenerate 4'th generation quarks that decay to ${{\mathit b}}{{\mathit W}}$ or ${{\mathit t}}{{\mathit W}}$ . Absence of signal in events with one lepton, same-sign dileptons or tri-leptons gives the bound. With a mass difference of 25 GeV/c${}^{2}$ between ${\mathit m}_{{{\mathit t}^{\,'}}}$ and ${\mathit m}_{{{\mathit b}^{\,'}}}$, the corresponding limit shifts by about $\pm20$ GeV/c${}^{2}$.
 31 Based on 4.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 7 TeV. CHATRCHYAN 2012X looked for events with trileptons or same-sign dileptons and at least one ${{\mathit b}}$ jet.
 32 Based on 4.8 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at 1.96 TeV. AALTONEN 2011J looked for events with ${{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}$5j (${}\geq{}$1 ${{\mathit b}}$ or ${{\mathit c}}$ ). No signal is observed and the bound ${\mathit \sigma (}$ ${{\mathit b}^{\,'}}{{\overline{\mathit b}}^{\,'}}{)}$ $<$ 30 fb for ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 375 GeV is found for B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1.
 33 Based on 34 pb${}^{-1}$ of data in ${{\mathit p}}{{\mathit p}}$ collisions at 7 TeV. CHATRCHYAN 2011L looked for multi-jet events with trileptons or same-sign dileptons. No excess above the SM background excludes ${\mathit m}_{{{\mathit b}^{\,'}}}$ between 255 and 361 GeV at 95$\%$ CL for B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1.
 34 Based on 2.7 fb${}^{-1}$ of data in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV. AALTONEN 2010H looked for pair production of heavy quarks which decay into ${{\mathit t}}{{\mathit W}^{-}}$ or ${{\mathit t}}{{\mathit W}^{+}}$ , in events with same sign dileptons (${{\mathit e}}$ or ${{\mathit \mu}}$ ), several jets and large missing $\mathit E_{T}$. The result is obtained for ${{\mathit b}^{\,'}}$ which decays into ${{\mathit t}}{{\mathit W}^{-}}$ . For the charge 5/3 quark (${{\mathit T}_{{5/3}}}$ ) which decays into ${{\mathit t}}{{\mathit W}^{+}}$ , ${\mathit m}_{{{\mathit T}_{{5/3}}}}$ $>$ 365 GeV (95$\%$ CL) is found when it has the charge $-1$/3 partner B of the same mass.
 35 FLACCO 2010 result is obtained from AALTONEN 2010H result of ${\mathit m}_{{{\mathit b}^{\,'}}}>$ 338 GeV, by relaxing the condition B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 100$\%$ when ${\mathit m}_{{{\mathit b}^{\,'}}}>$ ${\mathit m}_{{{\mathit t}^{\,'}}}$.
 36 Result is based on 1.06 fb${}^{-1}$ of data. No excess from the SM ${{\mathit Z}}$ +jet events is found when ${{\mathit Z}}$ decays into ${{\mathit e}}{{\mathit e}}$ or ${{\mathit \mu}}{{\mathit \mu}}$ . The ${\mathit m}_{{{\mathit b}^{\,'}}}$ bound is found by comparing the resulting upper bound on ${\mathit \sigma (}$ ${{\mathit b}^{\,'}}{{\overline{\mathit b}}^{\,'}}{)}$ [1-(1-B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ))${}^{2}$] and the LO estimate of the ${{\mathit b}^{\,'}}$ pair production cross section shown in Fig. 38 of the article.
 37 HUANG 2008 reexamined the ${{\mathit b}^{\,'}}$ mass lower bound of 268 GeV obtained in AALTONEN 2007C that assumes B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1, which does not hold for ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ 255 GeV. The lower mass bound is given in the plane of sin$^2(\theta _{ {{\mathit t}} {{\mathit b}^{\,'}} })$ and ${\mathit m}_{{{\mathit b}^{\,'}}}$.
 38 AFFOLDER 2000 looked for ${{\mathit b}^{\,'}}$ that decays in to ${{\mathit b}}$ +${{\mathit Z}}$ . The signal searched for is ${{\mathit b}}{{\mathit b}}{{\mathit Z}}{{\mathit Z}}$ events where one ${{\mathit Z}}$ decays into ${{\mathit e}^{+}}{{\mathit e}^{-}}$ or ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ and the other ${{\mathit Z}}$ decays hadronically. The bound assumes B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ )= 100$\%$. Between 100 GeV and 199 GeV, the 95$\%$CL upper bound on $\sigma\mathrm {( {{\mathit b}^{\,'}} \rightarrow {{\overline{\mathit b}}^{\,'}} )}{\times }B{}^{2}$( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) is also given (see their Fig.$~$2).
 39 ABE 1998N looked for ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ decays with displaced vertices. Quoted limit assumes B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ )=1 and ${{\mathit c}}{{\mathit \tau}_{{\mathit ^{'}}}}$ =1$~$cm. The limit is lower than ${\mathit m}_{{{\mathit Z}}}+{\mathit m}_{{{\mathit b}}}$ ($\sim{}$96 GeV) if ${{\mathit c}}{{\mathit \tau}}$ $>22~$cm or ${{\mathit c}}{{\mathit \tau}}$ $<0.009~$cm. See their Fig.$~$4.
 40 ABACHI 1997D searched for ${{\mathit b}^{\,'}}$ that decays mainly via FCNC. They obtained 95$\%$CL upper bounds on B( ${{\mathit b}^{\,'}}$ ${{\overline{\mathit b}}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}$ + 3 jets) and B( ${{\mathit b}^{\,'}}$ ${{\overline{\mathit b}}^{\,'}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$ + 2 jets), which can be interpreted as the lower mass bound ${\mathit m}_{{{\mathit b}^{\,'}}}>{\mathit m}_{{{\mathit Z}}}+{\mathit m}_{{{\mathit b}}}$.
 41 ABACHI 1995F bound on the top-quark also applies to ${{\mathit b}^{\,'}}$ and ${{\mathit t}^{\,'}}$ quarks that decay predominantly into ${{\mathit W}}$ . See FROGGATT 1997 .
 42 MUKHOPADHYAYA 1993 analyze CDF dilepton data of ABE 1992G in terms of a new quark decaying via flavor-changing neutral current. The above limit assumes B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ )=1$\%$. For an exotic quark decaying only via virtual ${{\mathit Z}}$ [B( ${{\mathit b}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ ) = 3$\%$], the limit is 85 GeV.
 43 ABE 1992 dilepton analysis limit of $>$85 GeV at CL=95$\%$ also applies to ${{\mathit b}^{\,'}}$ quarks, as discussed in ABE 1990B.
 44 ABE 1990B exclude the region 28$-$72 GeV.
 45 AKESSON 1990 searched for events having an electron with $\mathit p_{\mathit T}$ $>$ 12 GeV, missing momentum $>$ 15 GeV, and a jet with $\mathit E_{\mathit T}$ $>$ 10 GeV, $\vert \eta \vert$ $<$ $2.2$, and excluded ${\mathit m}_{{{\mathit b}^{\,'}}}$ between 30 and 69 GeV.
 46 For the reduction of the limit due to non-charged-current decay modes, see Fig.$~$19 of ALBAJAR 1990B.
 47 ALBAJAR 1988 study events at $\mathit E_{{\mathrm {cm}}}$ = 546 and 630 GeV with a muon or isolated electron, accompanied by one or more jets and find agreement with Monte Carlo predictions for the production of charm and bottom, without the need for a new quark. The lower mass limit is obtained by using a conservative estimate for the ${{\mathit b}^{\,'}}{{\overline{\mathit b}}^{\,'}}$ production cross section and by assuming that it cannot be produced in ${{\mathit W}}$ decays. The value quoted here is revised using the full $\mathit O(\alpha {}^{3}_{\mathit s}$) cross section of ALTARELLI 1988 .
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 SIRUNYAN 2020BI
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 SIRUNYAN 2017AU
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 CHATRCHYAN 2013I
JHEP 1301 154 Search for Heavy Quarks Decaying into a Top Quark and a ${{\mathit W}}$ or ${{\mathit Z}}$ Boson using Lepton + Jets Events in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV
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 CHATRCHYAN 2012BH
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PL B701 204 Search for a Heavy Bottom-Like Quark in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV
 AALTONEN 2010H
PRL 104 091801 Search for New Bottomlike Quark Pair Decays ${{\mathit Q}}$ ${{\overline{\mathit Q}}}$ $\rightarrow$ ( ${{\mathit t}}{{\mathit W}^{\mp}}$) ( ${{\overline{\mathit t}}}{{\mathit W}^{\pm}}$) in Same-Charge Dilepton Events
 FLACCO 2010
PRL 105 111801 Direct Mass Limits for Chiral Fourth-Generation Quarks in All Mixing Scenarios
 ABAZOV 2008X
PRL 101 111802 Search for Long-Lived Particles Decaying into Electron or Photon Pairs with the ${D0}$ Detector
 AALTONEN 2007C
PR D76 072006 Search for New Particles Leading to ${{\mathit Z}}$ +jets Final States in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96 TeV
 ACOSTA 2003
PRL 90 131801 Search for Long Lived Charged Massive Particles in ${{\overline{\mathit p}}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
 AFFOLDER 2000
PRL 84 835 Search for a Fourth Generation Quark More Massive than the ${{\mathit Z}}$ Boson in ${{\mathit p}}$ ${{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
 ABE 1998N
PR D58 051102 Search for Longlived Parents of ${{\mathit Z}}$ Bosons in ${{\mathit p}}$ ${{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
 ABACHI 1997D
PRL 78 3818 Search for a Fourth Generation Charge -1/3 Quark via Flavor Changing Neutral Current Decay
 ABACHI 1995F
PR D52 4877 Top Quark Search with the ${D0}$ $1992 - 1993$ Data Sample
PRL 68 447 A Lower Limit on the Top Quark Mass from Events with Two Leptons in ${{\overline{\mathit p}}}$ ${{\mathit p}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
PR D45 3921 A Limit on the Top Quark Mass from Proton Antiproton Collisions at $\sqrt {s }$ = 1.8 TeV
ZPHY C46 179 Search for Top Quark Production at the CERN ${{\overline{\mathit p}}}{{\mathit p}}$ Collider
ZPHY C48 1 Search for New Heavy Quarks in Proton Antiproton Collisions at $\sqrt {s }$ = 0.63 TeV