# MASS LIMITS for ${{\boldsymbol b}^{\,'}}$ (4${}^{\boldsymbol th}$ Generation) Quark or Hadron in ${{\boldsymbol e}^{+}}{{\boldsymbol e}^{-}}$ Collisions INSPIRE search

Search for hadrons containing a fourth-generation $−$1/3 quark denoted ${{\mathit b}^{\,'}}$.

The last column specifies the assumption for the decay mode ( ${{\mathit C}}{{\mathit C}}$ denotes the conventional charged-current decay) and the event signature which is looked for.
VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{>46.0}$ 95 1
 1990 F
ALEP any decay
• • • We do not use the following data for averages, fits, limits, etc. • • •
$\text{none 96 - 103}$ 95 2
 2007
DLPH ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit Z}}$ , ${{\mathit c}}{{\mathit W}}$
3
 1993 G
L3 Quarkonium
$>44.7$ 95
 1993 M
L3 $\Gamma\mathrm {({{\mathit Z}})}$
$>45$ 95
 1991 F
DLPH $\Gamma\mathrm {({{\mathit Z}})}$
$\text{none 19.4 - 28.2}$ 95
 1990 D
VNS Any decay; event shape
$>45.0$ 95
 1990 D
DLPH B( ${{\mathit C}}{{\mathit C}}$ ) = 1; event shape
$>44.5$ 95 4
 1990 D
DLPH ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit c}}{{\mathit H}^{-}}$ , ${{\mathit H}^{-}}$ $\rightarrow$ ${{\overline{\mathit c}}}{{\mathit s}}$ , ${{\mathit \tau}^{-}}{{\mathit \nu}}$
$>40.5$ 95 5
 1990 D
DLPH $\Gamma\mathrm {( {{\mathit Z}} \rightarrow hadrons)}$
$>28.3$ 95
 1990
TOPZ B(${\mathrm {FCNC}})=100\%$; isol. ${{\mathit \gamma}}$ or 4 jets
$>41.4$ 95 6
 1990 B
OPAL Any decay; acoplanarity
$>45.2$ 95 6
 1990 B
OPAL B( ${{\mathit C}}{{\mathit C}}$ ) = 1; acoplanarity
$>46$ 95 7
 1990 J
OPAL ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}{+}$ any
$>27.5$ 95 8
 1989 E
VNS B( ${{\mathit C}}{{\mathit C}}$ ) =1; ${{\mathit \mu}}$, ${{\mathit e}}$
$\text{none 11.4 - 27.3}$ 95 9
 1989 G
VNS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$ ) $>$ 10$\%$; isolated ${{\mathit \gamma}}$
$>44.7$ 95 10
 1989 C
MRK2 B( ${{\mathit C}}{{\mathit C}}$ )= 100$\%$; isol. track
$>42.7$ 95 10
 1989 C
MRK2 B( ${{\mathit b}}{{\mathit g}}$ )= 100$\%$; event shape
$>42.0$ 95 10
 1989 C
MRK2 Any decay; event shape
$>28.4$ 95 11, 12
 1989 C
TOPZ B( ${{\mathit C}}{{\mathit C}}$ ) =1; ${{\mathit \mu}}$
$>28.8$ 95 13
 1989
AMY B( ${{\mathit C}}{{\mathit C}}$ ) ${ {}\gtrsim{} }90\%$; ${{\mathit \mu}}$, ${{\mathit e}}$
$>27.2$ 95 13, 14
 1989
AMY any decay; event shape
$>29.0$ 95 13
 1989
AMY B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit g}}$ ) ${ {}\gtrsim{} }$ 85$\%$; event shape
$>24.4$ 95 15
 1988
AMY ${{\mathit \mu}},{{\mathit e}}$
$>23.8$ 95 16
 1988
AMY event shape
$>22.7$ 95 17
 1986
MRKJ ${{\mathit \mu}}$
$>21$ 18
 1984 C
TASS $\mathit R$, event shape
$>19$ 19
 1984 I
TASS Aplanarity
1  DECAMP 1990F looked for isolated charged particles, for isolated photons, and for four-jet final states. The modes ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit g}}$ for B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit g}}$ ) $>$ 65$\%$ ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$ for B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$ ) $>$ 5$\%$ are excluded. Charged Higgs decay were not discussed.
2  ABDALLAH 2007 searched for ${{\mathit b}^{\,'}}$ pair production at $\mathit E_{{\mathrm {cm}}}=196 - 209$ GeV, with 420$~$pb${}^{-1}$. No signal leads to the 95$\%$ CL upper limits on B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit Z}}$ ) and B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit c}}{{\mathit W}}$ ) for ${\mathit m}_{{{\mathit b}^{\,'}}}$ = 96 to 103 GeV.
3  ADRIANI 1993G search for vector quarkonium states near ${{\mathit Z}}$ and give limit on quarkonium-${{\mathit Z}}$ mixing parameter $\delta <(10 - 30$) GeV${}^{2}$ (95$\%$CL) for the mass $88 - 94.5$ GeV. Using Richardson potential, a 1S ( ${{\mathit b}^{\,'}}{{\overline{\mathit b}}^{\,'}}$ ) state is excluded for the mass range $87.7 - 94.7$ GeV. This range depends on the potential choice.
4  ABREU 1990D assumed ${\mathit m}_{{{\mathit H}^{-}}}$ $<$ ${\mathit m}_{{{\mathit b}^{\,'}}}$ $−$ 3 GeV.
5  Superseded by ABREU 1991F.
6  AKRAWY 1990B search was restricted to data near the ${{\mathit Z}}$ peak at $\mathit E_{{\mathrm {cm}}}$ = $91.26$ GeV at LEP. The excluded region is between $23.6$ and $41.4$ GeV if no ${{\mathit H}^{+}}$ decays exist. For charged Higgs decays the excluded regions are between (${\mathit m}_{{{\mathit H}^{+}}}$ $+1.5$ GeV) and $45.5$ GeV.
7  AKRAWY 1990J search for isolated photons in hadronic ${{\mathit Z}}$ decay and derive B( ${{\mathit Z}}$ $\rightarrow$ ${{\mathit b}^{\,'}}{{\overline{\mathit b}}^{\,'}}$ )$\cdot{}$B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}$ X)/B( ${{\mathit Z}}$ $\rightarrow$ hadrons) $<$ $2.2 \times 10^{-3}$. Mass limit assumes B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}$ X) $>$ 10$\%$.
8  ABE 1989E search at $\mathit E_{{\mathrm {cm}}}$ = 56$-$57 GeV at TRISTAN for multihadron events with a spherical shape (using thrust and acoplanarity) or containing isolated leptons.
9  ABE 1989G search was at $\mathit E_{{\mathrm {cm}}}$ = 55$-60.8$ GeV at TRISTAN.
10  If the photonic decay mode is large (B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$ ) $>$ 25$\%$), the ABRAMS 1989C limit is $45.4$ GeV. The limit for for Higgs decay ( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit c}}{{\mathit H}^{-}}$ , ${{\mathit H}^{-}}$ $\rightarrow$ ${{\overline{\mathit c}}}{{\mathit s}}$ ) is $45.2$ GeV.
11  ADACHI 1989C search was at $\mathit E_{{\mathrm {cm}}}$ = $56.5-60.8$ GeV at TRISTAN using multi-hadron events accompanying muons.
12  ADACHI 1989C also gives limits for any mixture of ${{\mathit C}}{{\mathit C}}$ and ${{\mathit b}}{{\mathit g}}$ decays.
13  ENO 1989 search at $\mathit E_{{\mathrm {cm}}}$ = 50$-60.8$ at TRISTAN.
14  ENO 1989 considers arbitrary mixture of the charged current, ${{\mathit b}}{{\mathit g}}$ , and ${{\mathit b}}{{\mathit \gamma}}$ decays.
15  IGARASHI 1988 searches for leptons in low-thrust events and gives $\Delta \mathit R({{\mathit b}^{\,'}}$) $<$ $0.26$ (95$\%$ CL) assuming charged current decay, which translates to ${\mathit m}_{{{\mathit b}^{\,'}}}$ $>$ $24.4$ GeV.
16  SAGAWA 1988 set limit ${\mathit \sigma (}$top${)}$ $<$ 6.1 pb at CL=95$\%$ for top-flavored hadron production from event shape analyses at $\mathit E_{{\mathrm {cm}}}$ = 52 GeV. By using the quark parton model cross-section formula near threshold, the above limit leads to lower mass bounds of 23.8 GeV for charge $−$1/3 quarks.
17  ADEVA 1986 give 95$\%$CL upper bound on an excess of the normalized cross section, $\Delta \mathit R$, as a function of the minimum c.m. energy (see their figure 3). Production of a pair of 1/3 charge quarks is excluded up to $\mathit E_{{\mathrm {cm}}}$ = 45.4 GeV.
18  ALTHOFF 1984C narrow state search sets limit $\Gamma\mathrm {( {{\mathit e}^{+}} {{\mathit e}^{-}} )}{}$B(hadrons) $<$2.4 keV CL = 95$\%$ and heavy charge 1/3 quark pair production $\mathit m$ $>$21 GeV, CL = 95$\%$.
19  ALTHOFF 1984I exclude heavy quark pair production for 7 $<\mathit m$ $<$19 GeV (1/3 charge) using aplanarity distributions (CL = 95$\%$).
References:
 ABDALLAH 2007
EPJ C50 507 Search for a Fourth Generation ${\mathit {\mathit b ^{\prime}}}$-Quark at LEP-II at $\sqrt {s }$ = $196 - 209$ GeV
PL B313 326 Search for Narrow Vector Resonances in the ${{\mathit Z}^{0}}$ Mass Range
PRPL 236 1 Results from the L3 Experiment at LEP
 ABREU 1991F
NP B367 511 Determination of ${{\mathit Z}^{0}}$ Resonance Parameters and Couplings from its Hadronic and Leptonic Decays
 ABE 1990D
PL B234 382 Measurement of R and Search for New Quark Flavors Decaying into Multijet Final States in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions between 54 GeV and 64.1 GeV
 ABREU 1990D
PL B242 536 Search for ${\mathit {\mathit t}}$ and ${\mathit {\mathit b ^{\prime}}}$ Quarks in Hadronic Decays of the ${{\mathit Z}^{0}}$ Boson
PL B234 197 A Search for a ${\mathit {\mathit b ^{\prime}}}$ Quark with Flavor Changing Neutral Current Decay Modes at TRISTAN
 AKRAWY 1990B
PL B236 364 A Search for the ${\mathit {\mathit t}}$ and ${\mathit {\mathit b ^{\prime}}}$ Quarks in Hadronic ${{\mathit Z}^{0}}$ Decays
 AKRAWY 1990J
PL B246 285 Evidence for Final State Photons in Multihadronic Decays of the ${{\mathit Z}^{0}}$
 DECAMP 1990F
PL B236 511 A Search for New Quarks and Leptons from ${{\mathit Z}^{0}}$ Decay
 ABE 1989G
PRL 63 1776 Search for Isolated Photons from Flavor-Changing Neutral-Current Decay of a New Quark at the KEK ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collider TRISTAN
 ABE 1989E
PR D39 3524 Search for a Fourth Generation Quark with $\mathit q$ = $\mathit e$/3 in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 56-57 GeV
 ABRAMS 1989C
PRL 63 2447 Searches for New Quarks and Leptons Produced in ${{\mathit Z}^{0}}$ Boson Decay
PL B229 427 A Search for a Fourth Generation Charge -1/3 (${\mathit {\mathit b ^{\prime}}}$) Quark Using Inclusive Muons in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilations at $\sqrt {s }$ = 5
 ENO 1989
PRL 63 1910 Search for a Fourth Generation Charge -1/3 Quark
 IGARASHI 1988
PRL 60 2359 Search for Isolated Leptons in Low Thrust ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation Events at $\sqrt {s }$ = 50 and 52 GeV
 SAGAWA 1988
PRL 60 93 Measurements of $\mathit R$ and a Search for Heavy Quark Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at $\sqrt {s }$ = 50 and 52 GeV
PR D34 681 Study of Hadron and Inclusive Muon Production from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 39.79 ${}\leq{}$ $\mathit E_{{\mathrm {cm}}}{}\leq{}$ 46.78 GeV
ZPHY C22 307 Jet Production and Fragmentation in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 12-43 GeV
PL 138B 441 Measurement of $\mathit R$ and Search for the Top Quark in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation between 39.8 and 45.2 GeV
EPJ C51 249 Investigation of Colour Reconnection in ${{\mathit W}}{{\mathit W}}$ Events with the DELPHI Detector at LEP-2