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

INSPIRE  
VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{> 1570}$ 95 1
SIRUNYAN
2020BI
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$ ) = 1
$\bf{> 1390}$ 95 1
SIRUNYAN
2020BI
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$> 1130$ 95 2
SIRUNYAN
2019AQ
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$>1230$ 95 3
SIRUNYAN
2019BW
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$\bf{> 1350}$ 95 4
AABOUD
2018AW
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 1000$ 95 5
AABOUD
2018CE
 ATLS ${}\geq{}2{{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}1{{\mathit b}}$ j
$> 950$ 95 6
AABOUD
2018CL
 ATLS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 1010$ 95 7, 8
AABOUD
2018CP
 ATLS 2,3${{\mathit \ell}}$ , singlet model
$> 1140$ 95 6, 9
AABOUD
2018CP
 ATLS 2,3${{\mathit \ell}}$ , doublet model
$> 1220$ 95 10, 11
AABOUD
2018CR
 ATLS singlet ${{\mathit b}^{\,'}}$ . ATLAS Combination
$> 1370$ 95 10, 12
AABOUD
2018CR
 ATLS ${{\mathit b}^{\,'}}$ in a weak isospin doublet (${{\mathit t}^{\,'}}$ ,${{\mathit b}^{\,'}}$ ). ATLAS combination.
$> 910$ 95 13
SIRUNYAN
2018BM
 CMS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 845$ 95 14
SIRUNYAN
2018Q
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit u}}$ ) = 1
$> 730$ 95 15
SIRUNYAN
2017AU
 CMS
$> 880$ 95 16
KHACHATRYAN
2016AN
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 620$ 95 17
AAD
2015BY
 ATLS ${{\mathit W}}{{\mathit t}}$ , ${{\mathit Z}}{{\mathit b}}$ , ${{\mathit h}}{{\mathit b}}$ modes
$> 730$ 95 18
AAD
2015BY
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 810$ 95 19
AAD
2015Z
 ATLS
$> 755$ 95 20
AAD
2014AZ
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 675$ 95 21
CHATRCHYAN
2013I
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$\bf{> 190}$ 95 22
ABAZOV
2008X
 D0 c = 200mm
$\bf{> 190}$ 95 23
ACOSTA
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
AAD
2015AR
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$ ) = 1
$> 690$ 95 25
AAD
2015CN
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$ ) = 1 (${{\mathit q}}$ =${{\mathit u}}$ )
$> 480$ 95 26
AAD
2012AT
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 400$ 95 27
AAD
2012AU
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ ) = 1
$> 350$ 95 28
AAD
2012BC
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$ ) = 1 (${{\mathit q}}$ =${{\mathit u}}$ ,${{\mathit c}}$ )
$> 450$ 95 29
AAD
2012BE
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 685$ 95 30
CHATRCHYAN
2012BH
 CMS ${\mathit m}_{{{\mathit t}^{\,'}}}$ = ${\mathit m}_{{{\mathit b}^{\,'}}}$
$> 611$ 95 31
CHATRCHYAN
2012X
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$ ) = 1
$> 372$ 95 32
AALTONEN
2011J
 CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$> 361$ 95 33
CHATRCHYAN
2011L
 CMS Repl. by CHATRCHYAN 2012X
$> 338$ 95 34
AALTONEN
2010H
 CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$\text{>380 - 430}$ 95 35
FLACCO
2010
RVUE ${\mathit m}_{{{\mathit b}^{\,'}}}>$ ${\mathit m}_{{{\mathit t}^{\,'}}}$
$> 268$ 95 36, 37
AALTONEN
2007C
 CDF B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ) = 1
$>199$ 95 38
AFFOLDER
2000
CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$
$>148$ 95 39
ABE
1998N
 CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ + vertex
$>96$ 95 40
ABACHI
1997D
 D0 NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$
$>128$ 95 41
ABACHI
1995F
 D0 ${{\mathit \ell}}{{\mathit \ell}}$ $+$ jets, ${{\mathit \ell}}$ $+$ jets
$>75$ 95 42
MUKHOPADHYAYA
1993
RVUE NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \ell}}{{\mathit \ell}}$
$>85$ 95 43
ABE
1992
CDF CC: ${{\mathit \ell}}{{\mathit \ell}}$
$>72$ 95 44
ABE
1990B
 CDF CC: ${{\mathit e}}$ $+$ ${{\mathit \mu}}$
$>54$ 95 45
AKESSON
1990
UA2 CC: ${{\mathit e}}$ $+$ jets + $\not E_T$
$>43$ 95 46
ALBAJAR
1990B
 UA1 CC: ${{\mathit \mu}}$ $+$ jets
$>34$ 95 47
ALBAJAR
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 .
References:
SIRUNYAN 2020BI
PR D102 112004 A search for bottom-type, vector-like quark pair production in a fully hadronic final state in proton-proton collisions at $\sqrt{s} =$ 13 TeV
SIRUNYAN 2019AQ
EPJ C79 364 Search for vector-like quarks in events with two oppositely charged leptons and jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV
SIRUNYAN 2019BW
PR D100 072001 Search for pair production of vectorlike quarks in the fully hadronic final state
AABOUD 2018CR
PRL 121 211801 Combination of the searches for pair-produced vector-like partners of the third-generation quarks at $\sqrt{s} =$ 13 TeV with the ATLAS detector
AABOUD 2018CP
PR D98 112010 Search for pair- and single-production of vector-like quarks in final states with at least one $Z$ boson decaying into a pair of electrons or muons in $pp$ collision data collected with the ATLAS detector at $\sqrt{s} = 13$ TeV
AABOUD 2018CL
PR D98 092005 Search for pair production of heavy vector-like quarks decaying into hadronic final states in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector
AABOUD 2018AW
JHEP 1808 048 Search for pair production of heavy vector-like quarks decaying into high-$p_T$ $W$ bosons and top quarks in the lepton-plus-jets final state in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
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 2018Q
PR D97 072008 Search for vectorlike light-flavor quark partners in proton-proton collisions at $\sqrt s$ =8??TeV
SIRUNYAN 2018BM
JHEP 1808 177 Search for vector-like T and B quark pairs in final states with leptons at $\sqrt{s} =$ 13 TeV
SIRUNYAN 2017AU
JHEP 1711 085 Search for Pair Production of Vector-Like and Quarks in Single-Lepton Final States using Boosted Jet Substructure in Proton-Proton Collisions at $\sqrt {s }$ = 13 TeV
KHACHATRYAN 2016AN
PR D93 112009 Search for Pair-Produced Vectorlike Quarks in Proton-Proton Collisions at $\sqrt {s }$ = 8 TeV
AAD 2015AR
JHEP 1508 105 Search for Production of Vector-Like Quark Pairs and of Four Top Quarks in the Lepton-plus-Jets Final State in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
AAD 2015BY
JHEP 1510 150 Analysis of Events with ${\mathit {\mathit b}}$-Jets and a Pair of Leptons of the Same Charge in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
AAD 2015Z
PR D91 112011 Search for Vector-Like Quarks in Events with One Isolated Lepton, Missing Transverse Momentum and Jets at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
AAD 2015CN
PR D92 112007 Search for Pair Production of a New heavy Quark that Decays into a ${{\mathit W}}$ Boson and a Light Quark in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
AAD 2014AZ
JHEP 1411 104 Search for Pair and Single Production of New Heavy Quarks that Decay to a ${{\mathit Z}}$ Boson and a Third-Generation Quark in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
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
AAD 2012BE
JHEP 1204 069 Search for Same-Sign Top-Quark Production and Fourth-Generation Down-Type Quarks in ${{\mathit p}}{{\mathit p}}$ Collisions at with the ATLAS Detector
AAD 2012BC
PR D86 012007 Search for Pair-Produced Heavy Quarks Decaying to ${{\mathit W}}{\mathit {\mathit q}}$ in the Two-Lepton Channel at $\sqrt {s }$ = 7 TeV with the ATLAS Detector
AAD 2012AT
PRL 109 032001 Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying ${{\mathit W}}$ Bosons
AAD 2012AU
PRL 109 071801 Search for Pair Production of a New ${\mathit {\mathit b ^{\prime}}}$ Quark that Decays into a ${{\mathit Z}}$ Boson and a Bottom Quark with the ATLAS Detector
CHATRCHYAN 2012X
JHEP 1205 123 Search for Heavy Bottom-Like Quarks in 4.9 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV
CHATRCHYAN 2012BH
PR D86 112003 Combined Search for the Quarks of a Sequential Fourth Generation
AALTONEN 2011J
PRL 106 141803 Search for Heavy Bottomlike Quarks Decaying to an Electron or Muon and Jets in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96 TeV
CHATRCHYAN 2011L
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
MUKHOPADHYAYA 1993
PR D48 2105 Tevatron Mass Limits for Heavy Quarks Decaying via Flavor Changing Neutral Current
ABE 1992
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
Also
PR D45 3921 A Limit on the Top Quark Mass from Proton Antiproton Collisions at $\sqrt {s }$ = 1.8 TeV
ABE 1990B
PRL 64 147 Search for New Heavy Quarks in Electron Muon Events at the Fermilab Tevatron Collider
AKESSON 1990
ZPHY C46 179 Search for Top Quark Production at the CERN ${{\overline{\mathit p}}}{{\mathit p}}$ Collider
ALBAJAR 1990B
ZPHY C48 1 Search for New Heavy Quarks in Proton Antiproton Collisions at $\sqrt {s }$ = 0.63 TeV
ALBAJAR 1988
ZPHY C37 505 Search for New Heavy Quarks at CERN Proton-Antiproton Collider