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

INSPIRE   PDGID:
Q008BPE
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
DECAMP
1990F
 ALEP any decay
• • We do not use the following data for averages, fits, limits, etc. • •
$\text{none 96 - 103}$ 95 2
ABDALLAH
2007
DLPH ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit Z}}$, ${{\mathit c}}{{\mathit W}}$
3
ADRIANI
1993G
 L3 Quarkonium
$>44.7$ 95
ADRIANI
1993M
 L3 $\Gamma\mathrm {({{\mathit Z}})}$
$>45$ 95
ABREU
1991F
 DLPH $\Gamma\mathrm {({{\mathit Z}})}$
$\text{none 19.4 - 28.2}$ 95
ABE
1990D
 VNS Any decay; event shape
$>45.0$ 95
ABREU
1990D
 DLPH B(${{\mathit C}}{{\mathit C}}$) = 1; event shape
$>44.5$ 95 4
ABREU
1990D
 DLPH ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit c}}{{\mathit H}^{-}}$, ${{\mathit H}^{-}}$ $\rightarrow$ ${{\overline{\mathit c}}}{{\mathit s}}$, ${{\mathit \tau}^{-}}{{\mathit \nu}}$
$>40.5$ 95 5
ABREU
1990D
 DLPH $\Gamma\mathrm {( {{\mathit Z}} \rightarrow hadrons)}$
$>28.3$ 95
ADACHI
1990
TOPZ B(${\mathrm {FCNC}})=100\%$; isol. ${{\mathit \gamma}}$ or 4 jets
$>41.4$ 95 6
AKRAWY
1990B
 OPAL Any decay; acoplanarity
$>45.2$ 95 6
AKRAWY
1990B
 OPAL B(${{\mathit C}}{{\mathit C}}$) = 1; acoplanarity
$>46$ 95 7
AKRAWY
1990J
 OPAL ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}{+}$ any
$>27.5$ 95 8
ABE
1989E
 VNS B(${{\mathit C}}{{\mathit C}}$) =1; ${{\mathit \mu}}$, ${{\mathit e}}$
$\text{none 11.4 - 27.3}$ 95 9
ABE
1989G
 VNS B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \gamma}}$) $>$ 10$\%$; isolated ${{\mathit \gamma}}$
$>44.7$ 95 10
ABRAMS
1989C
 MRK2 B(${{\mathit C}}{{\mathit C}}$)= 100$\%$; isol. track
$>42.7$ 95 10
ABRAMS
1989C
 MRK2 B(${{\mathit b}}{{\mathit g}}$)= 100$\%$; event shape
$>42.0$ 95 10
ABRAMS
1989C
 MRK2 Any decay; event shape
$>28.4$ 95 11, 12
ADACHI
1989C
 TOPZ B(${{\mathit C}}{{\mathit C}}$) =1; ${{\mathit \mu}}$
$>28.8$ 95 13
ENO
1989
AMY B(${{\mathit C}}{{\mathit C}}$) ${ {}\gtrsim{} }90\%$; ${{\mathit \mu}}$, ${{\mathit e}}$
$>27.2$ 95 13, 14
ENO
1989
AMY any decay; event shape
$>29.0$ 95 13
ENO
1989
AMY B( ${{\mathit b}^{\,'}}$ $\rightarrow$ ${{\mathit b}}{{\mathit g}}$) ${ {}\gtrsim{} }$ 85$\%$; event shape
$>24.4$ 95 15
IGARASHI
1988
AMY ${{\mathit \mu}},{{\mathit e}}$
$>23.8$ 95 16
SAGAWA
1988
AMY event shape
$>22.7$ 95 17
ADEVA
1986
MRKJ ${{\mathit \mu}}$
$>21$ 18
ALTHOFF
1984C
 TASS $\mathit R$, event shape
$>19$ 19
ALTHOFF
1984I
 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 $\delta {{\mathit m}^{2}}_{}<(10 - 30$) 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