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

INSPIRE   PDGID:
Q008BPP
VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{> 1420}$ 95 1
AAD
2023AV
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$) = 1
$\bf{> 1560}$ 95 2
TUMASYAN
2023V
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$\bf{> 1570}$ 95 3
SIRUNYAN
2020BI
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$) = 1
$> 1000$ 95 4
AABOUD
2018CE
 ATLS ${}\geq{}2{{\mathit \ell}}$ + $\not E_T$ + ${}\geq{}1{{\mathit b}}$j
$> 950$ 95 5
AABOUD
2018CL
 ATLS ${{\mathit W}}{{\mathit t}}$, ${{\mathit Z}}{{\mathit b}}$, ${{\mathit h}}{{\mathit b}}$ modes
$> 1010$ 95 6, 7
AABOUD
2018CP
 ATLS 2,3${{\mathit \ell}}$, singlet model
$> 1140$ 95 5, 8
AABOUD
2018CP
 ATLS 2,3${{\mathit \ell}}$, doublet model
$> 1220$ 95 9, 10
AABOUD
2018CR
 ATLS singlet ${{\mathit b}^{\,'}}$. ATLAS Combination
$> 1370$ 95 9, 11
AABOUD
2018CR
 ATLS ${{\mathit b}^{\,'}}$ in a weak isospin doublet (${{\mathit t}^{\,'}},{{\mathit b}^{\,'}}$). ATLAS combination.
$> 845$ 95 12
SIRUNYAN
2018Q
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit u}}$) = 1
$> 730$ 95 13
SIRUNYAN
2017AU
 CMS
$> 810$ 95 14
AAD
2015Z
 ATLS
$\bf{> 190}$ 95 15
ABAZOV
2008X
 D0 c = 200mm
$\bf{> 190}$ 95 16
ACOSTA
2003
CDF quasi-stable ${{\mathit b}^{\,'}}$
• • We do not use the following data for averages, fits, limits, etc. • •
$> 1460$ 95 17
AAD
2023AG
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 1390$ 95 3
SIRUNYAN
2020BI
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$) = 1
$> 1130$ 95 18
SIRUNYAN
2019AQ
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$) = 1
$>1230$ 95 19
SIRUNYAN
2019BW
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 1350$ 95 20
AABOUD
2018AW
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 910$ 95 21
SIRUNYAN
2018BM
 CMS ${{\mathit W}}{{\mathit t}}$, ${{\mathit Z}}{{\mathit b}}$, ${{\mathit h}}{{\mathit b}}$ modes
$> 880$ 95 22
KHACHATRYAN
2016AN
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$\text{<350, 580 - 635, >700}$ 95 23
AAD
2015AR
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit H}}{{\mathit b}}$) = 1
$> 620$ 95 24
AAD
2015BY
 ATLS ${{\mathit W}}{{\mathit t}}$, ${{\mathit Z}}{{\mathit b}}$, ${{\mathit h}}{{\mathit b}}$ modes
$> 730$ 95 25
AAD
2015BY
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 690$ 95 26
AAD
2015CN
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$) = 1 (${{\mathit q}}={{\mathit u}}$)
$> 755$ 95 27
AAD
2014AZ
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 675$ 95 28
CHATRCHYAN
2013I
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 480$ 95 29
AAD
2012AT
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 400$ 95 30
AAD
2012AU
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$) = 1
$> 350$ 95 31
AAD
2012BC
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit q}}$) = 1 (${{\mathit q}}={{\mathit u}},{{\mathit c}}$)
$> 450$ 95 32
AAD
2012BE
 ATLS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 685$ 95 33
CHATRCHYAN
2012BH
 CMS ${\mathit m}_{{{\mathit t}^{\,'}}}$ = ${\mathit m}_{{{\mathit b}^{\,'}}}$
$> 611$ 95 34
CHATRCHYAN
2012X
 CMS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$) = 1
$> 372$ 95 35
AALTONEN
2011J
 CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$> 361$ 95 36
CHATRCHYAN
2011L
 CMS Repl. by CHATRCHYAN 2012X
$> 338$ 95 37
AALTONEN
2010H
 CDF ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit W}}{{\mathit t}}$
$\text{>380 - 430}$ 95 38
FLACCO
2010
RVUE ${\mathit m}_{{{\mathit b}^{\,'}}}>$ ${\mathit m}_{{{\mathit t}^{\,'}}}$
$> 268$ 95 39, 40
AALTONEN
2007C
 CDF B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ) = 1
$>199$ 95 41
AFFOLDER
2000
CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$
$>148$ 95 42
ABE
1998N
 CDF NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit b}}$ + vertex
$>96$ 95 43
ABACHI
1997D
 D0 NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$
$>128$ 95 44
ABACHI
1995F
 D0 ${{\mathit \ell}}{{\mathit \ell}}$ $+$ jets, ${{\mathit \ell}}$ $+$ jets
$>75$ 95 45
MUKHOPADHYAYA
1993
RVUE NC: ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \ell}}{{\mathit \ell}}$
$>85$ 95 46
ABE
1992
CDF CC: ${{\mathit \ell}}{{\mathit \ell}}$
$>72$ 95 47
ABE
1990B
 CDF CC: ${{\mathit e}}$ $+$ ${{\mathit \mu}}$
$>54$ 95 48
AKESSON
1990
UA2 CC: ${{\mathit e}}$ $+$ jets + $\not E_T$
$>43$ 95 49
ALBAJAR
1990B
 UA1 CC: ${{\mathit \mu}}$ $+$ jets
$>34$ 95 50
ALBAJAR
1988
UA1 CC: ${{\mathit e}}$ or ${{\mathit \mu}}$ + jets
1  AAD 2023AV based on 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair production of vector-like ${{\mathit b}^{\,'}}$ is searched for in the mode ${{\mathit \ell}^{\pm}}{{\mathit \ell}^{\mp}}$ + ${}\geq{}$2j (${}\geq{}$1b-tagged) + $\not E_T$ or with 3${{\mathit \ell}}$. The data are consistent with the SM background predictions and limits are obtained for different branching ratios.
2  TUMASYAN 2023V based on 138 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair production of vector-like ${{\mathit b}^{\,'}}$ is seached for in the single-lepton, same-sign charge dilepton and multi-lepton channels. The data are consistent with the SM background predictions and limits are obtained for different branching ratios.
3  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.
4  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.
5  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.
6  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.
7  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.
8  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.
9  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.
10  The limit is for the singlet ${{\mathit b}^{\,'}}$.
11  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.
12  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.
13  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.
14  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 ${{\mathit b}^{\,'}}$.
15  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.
16  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.$~$3.
17  AAD 2023AG based on 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ data at $\sqrt {s }$ = 13 TeV. Pair production of vector-like top or bs is searched for in the mode 1${{\mathit \ell}}$ + ${}\geq{}$4j(${}\geq{}$1b-tagged) + $\not E_T$. The data are consistent with the SM background predictions and limits are obtained for different branching ratios. Masses below 1.59 TeV are excluded assuming a mass-degenerate vector-like doublet (${{\mathit t}^{\,'}},{{\mathit b}^{\,'}}$) model.
18  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 ${{\mathit b}^{\,'}}$.
19  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.
20  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.
21  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.
22  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.
23  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.
24  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.
25  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.
26  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.
27  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.
28  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.
29  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 ${{\mathit W}}$.
30  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.
31  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{}$2 jets.
32  Based on 1.04 fb${}^{-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.
33  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${}^{2}$.
34  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.
35  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.
36  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.
37  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.
38  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 ${\mathit m}_{{{\mathit b}^{\,'}}}>$ ${\mathit m}_{{{\mathit t}^{\,'}}}$.
39  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.
40  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 ${\mathit m}_{{{\mathit b}^{\,'}}}$.
41  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).
42  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.
43  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 ${\mathit m}_{{{\mathit b}^{\,'}}}>{\mathit m}_{{{\mathit Z}}}+{\mathit m}_{{{\mathit b}}}$.
44  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.
45  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.
46  ABE 1992 dilepton analysis limit of $>$85 GeV at CL=95$\%$ also applies to ${{\mathit b}^{\,'}}$ quarks, as discussed in ABE 1990B.
47  ABE 1990B exclude the region 28$-$72 GeV.
48  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.
49  For the reduction of the limit due to non-charged-current decay modes, see Fig.$~$19 of ALBAJAR 1990B.
50  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