Limits for ${{\mathit Z}_{{{\chi}}}}$ INSPIRE search

 ${{\mathit Z}_{{{\chi}}}}$ is the extra neutral boson in SO(10) $\rightarrow$ SU(5) ${\times }$ U(1)$_{{{\mathit \chi}}}$. ${{\mathit g}_{{{\chi}}}}$ = ${{\mathit e}}$/cos $\theta _{\mathit W}$ is assumed unless otherwise stated. We list limits with the assumption $\rho ~=~$1 but with no further constraints on the Higgs sector. Values in parentheses assume stronger constraint on the Higgs sector motivated by superstring models. Values in brackets are from cosmological and astrophysical considerations and assume a light right-handed neutrino.
S056ZCH
VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{ > 4800}$ OUR LIMIT
$\bf{\text{none 250 - 4800}}$ 95 1
AAD
2019L
 ATLS ${{\mathit p}}{{\mathit p}}$; ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ , ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$> 4100$ 95 2
AABOUD
2017AT
 ATLS ${{\mathit p}}{{\mathit p}}$; ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
3
HERBERMANN
2025
COSM $\Delta N_{{\mathrm {eff}}}$; light ${{\mathit \nu}_{{{R}}}}$
4
BOBOVNIKOV
2018
RVUE ${{\mathit p}}{{\mathit p}}$, ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit W}^{+}}{{\mathit W}^{-}}$
$> 3050$ 95 5
AABOUD
2016U
 ATLS ${{\mathit p}}{{\mathit p}}$; ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$> 2620$ 95 6
AAD
2014V
 ATLS ${{\mathit p}}{{\mathit p}}$, ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$> 1970$ 95 7
AAD
2012CC
 ATLS ${{\mathit p}}{{\mathit p}}$, ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$> 930$ 95 8
AALTONEN
2011I
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$; ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$> 903$ 95 9
ABAZOV
2011A
 D0 ${{\mathit p}}{{\overline{\mathit p}}}$, ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$> 1022$ 95 10
DEL-AGUILA
2010
RVUE Electroweak
$> 862$ 95 9
AALTONEN
2009T
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$, ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$> 892$ 95 11
AALTONEN
2009V
 CDF Repl. by AALTONEN 2011I
$> 1141$ 95 12
ERLER
2009
RVUE Electroweak
$> 822$ 95 9
AALTONEN
2007H
 CDF Repl. by AALTONEN 2009T
$> 680$ 95
SCHAEL
2007A
 ALEP ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$> 545$ 95 13
ABDALLAH
2006C
 DLPH ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$> 740$ 9
ABULENCIA
2006L
 CDF Repl. by AALTONEN 2007H
$> 690$ 95 14
ABULENCIA
2005A
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$; ${{\mathit Z}_{{{\chi}}}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$>781$ 95 15
ABBIENDI
2004G
 OPAL ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$>2100$ 16
BARGER
2003B
 COSM Nucleosynthesis; light ${{\mathit \nu}_{{{R}}}}$
$>680$ 95 17
CHEUNG
2001B
 RVUE Electroweak
$>440$ 95 18
ABREU
2000S
 DLPH ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$>533$ 95 19
BARATE
2000I
 ALEP Repl. by SCHAEL 2007A
$>554$ 95 20
CHO
2000
RVUE Electroweak
21
ERLER
2000
RVUE ${}^{}\mathrm {Cs}$
22
ROSNER
2000
RVUE ${}^{}\mathrm {Cs}$
$>545$ 95 23
ERLER
1999
RVUE Electroweak
$\text{(>1368)}$ 95 24
ERLER
1999
RVUE Electroweak
$>215$ 95 25
CONRAD
1998
RVUE ${{\mathit \nu}_{{{\mu}}}}{{\mathit N}}$ scattering
$>595$ 95 26
ABE
1997S
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$; ${{\mathit Z}}{}^{′}_{\chi }$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
$>190$ 95 27
ARIMA
1997
VNS Bhabha scattering
$>262$ 95 28
VILAIN
1994B
 CHM2 ${{\mathit \nu}_{{{\mu}}}}$ ${{\mathit e}}$ $\rightarrow$ ${{\mathit \nu}_{{{\mu}}}}{{\mathit e}}$; ${{\overline{\mathit \nu}}_{{{\mu}}}}$ ${{\mathit e}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{{\mu}}}}{{\mathit e}}$
$\text{[>1470]}$ 29
FARAGGI
1991
COSM Nucleosynthesis; light ${{\mathit \nu}_{{{R}}}}$
$>231$ 90 30
ABE
1990F
 VNS ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$\text{[> 1140]}$ 31
GONZALEZ-GARC..
1990D
 COSM Nucleosynthesis; light ${{\mathit \nu}_{{{R}}}}$
$\text{[> 2100]}$ 32
GRIFOLS
1990
ASTR SN 1987A; light ${{\mathit \nu}_{{{R}}}}$
1  AAD 2019L search for resonances decaying to ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV.
2  AABOUD 2017AT search for resonances decaying to ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV.
3  HERBERMANN 2025 limit is from Atacama Cosmology Telescope (ACT) DR6 limit on effective number of light neutrino species $\Delta N_{{\mathrm {eff}}}$ $<$ 0.17. See their Fig. 1 for limits in mass-coupling plane.
4  BOBOVNIKOV 2018 use the ATLAS limits on $\sigma $( ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit Z}^{\,'}})\cdot{}$B( ${{\mathit Z}^{\,'}}$ $\rightarrow$ ${{\mathit W}^{+}}{{\mathit W}^{-}}$) to constrain the ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing parameter $\xi $. See their Fig. 9 for limits in $\mathit M_{{{\mathit Z}^{\,'}}}−\xi $ plane.
5  AABOUD 2016U search for resonances decaying to ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV.
6  AAD 2014V search for resonances decaying to ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV.
7  AAD 2012CC search for resonances decaying to ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 7 TeV.
8  AALTONEN 2011I search for resonances decaying to ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV.
9  ABAZOV 2011A, AALTONEN 2009T, AALTONEN 2007H, and ABULENCIA 2006L search for resonances decaying to ${{\mathit e}^{+}}{{\mathit e}^{-}}$ in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96$~$TeV.
10  DEL-AGUILA 2010 give 95$\%$ CL limit on the ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing $-0.0011<\theta <$ 0.0007.
11  AALTONEN 2009V search for resonances decaying to ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96$~$TeV.
12  ERLER 2009 give 95$\%$ CL limit on the ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing $-0.0016<\theta <$ 0.0006.
13  ABDALLAH 2006C give 95$\%$ CL limit $\vert \theta \vert <$ 0.0031. See their Fig. 14 for limit contours in the mass-mixing plane.
14  ABULENCIA 2005A search for resonances decaying to electron or muon pairs in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\sqrt {s }$ = 1.96 TeV.
15  ABBIENDI 2004G give 95$\%$ CL limit on ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing $−$0.00099 $<\theta <$ 0.00194. See their Fig. 20 for the limit contour in the mass-mixing plane. $\sqrt {s }$ = 91 to 207$~$GeV.
16  BARGER 2003B limit is from the nucleosynthesis bound on the effective number of light neutrino $\delta \mathit N_{{{\mathit \nu}}}<$1. The quark-hadron transition temperature $\mathit T_{\mathit c}$=150 MeV is assumed. The limit with $\mathit T_{\mathit c}$=400 MeV is $>$4300 GeV.
17  CHEUNG 2001B limit is derived from bounds on contact interactions in a global electroweak analysis.
18  ABREU 2000S give 95$\%$ CL limit on ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing $\vert \theta \vert <0.0017$. See their Fig.$~$6 for the limit contour in the mass-mixing plane. $\sqrt {\mathit s }$=90 to 189 GeV.
19  BARATE 2000I search for deviations in cross section and asymmetries in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ fermions at $\sqrt {\mathit s }$=90 to 183 GeV. Assume $\theta $=0. Bounds in the mass-mixing plane are shown in their Figure$~$18.
20  CHO 2000 use various electroweak data to constrain ${{\mathit Z}^{\,'}}$ models assuming ${\mathit m}_{{{\mathit H}}}$=100 GeV. See Fig.$~$3 for limits in the mass-mixing plane.
21  ERLER 2000 discuss the possibility that a discrepancy between the observed and predicted values of ${{\mathit Q}_{{{W}}}}({}^{}\mathrm {Cs}$) is due to the exchange of ${{\mathit Z}^{\,'}}$. The data are better described in a certain class of the ${{\mathit Z}^{\,'}}$ models including ${{\mathit Z}_{{{LR}}}}$ and ${{\mathit Z}_{{{\chi}}}}$.
22  ROSNER 2000 discusses the possibility that a discrepancy between the observed and predicted values of ${{\mathit Q}_{{{W}}}}({}^{}\mathrm {Cs}$) is due to the exchange of ${{\mathit Z}^{\,'}}$. The data are better described in a certain class of the ${{\mathit Z}^{\,'}}$ models including ${{\mathit Z}_{{{\chi}}}}$.
23  ERLER 1999 give 90$\%$ CL limit on the ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing $-0.0020<\theta <0.0015$.
24  ERLER 1999 assumes 2 Higgs doublets, transforming as 10 of SO(10), embedded in $\mathit E_{6}$.
25  CONRAD 1998 limit is from measurements at CCFR, assuming no ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing.
26  ABE 1997S find $\sigma\mathrm {({{\mathit Z}^{\,'}})}{\times }B({{\mathit e}^{+}}{{\mathit e}^{-}},{{\mathit \mu}^{+}}{{\mathit \mu}^{-}})<40~$fb for ${\mathit m}_{{{\mathit Z}^{\,'}}}>600$ GeV at $\sqrt {\mathit s }$= 1.8 TeV.
27  ${{\mathit Z}}-{{\mathit Z}^{\,'}}$ mixing is assumed to be zero. $\sqrt {\mathit s }$= $57.77$ GeV.
28  VILAIN 1994B assume ${\mathit m}_{{{\mathit t}}}$ = 150 GeV and $\theta $=0. See Fig.$~$2 for limit contours in the mass-mixing plane.
29  FARAGGI 1991 limit assumes the nucleosynthesis bound on the effective number of neutrinos $\Delta {{\mathit N}_{{{\nu}}}}$ $<$ $0.5$ and is valid for ${\mathit m}_{{{\mathit \nu}_{{{R}}}}}$ $<$ 1 MeV.
30  ABE 1990F use data for $\mathit R$, $\mathit R_{{{\mathit \ell}} {{\mathit \ell}}}$, and $\mathit A_{{{\mathit \ell}} {{\mathit \ell}}}$. ABE 1990F fix ${\mathit m}_{{{\mathit W}}}$ = $80.49$ $\pm0.43$ $\pm0.24$ GeV and ${\mathit m}_{{{\mathit Z}}}$ = $91.13$ $\pm0.03$ GeV.
31  Assumes the nucleosynthesis bound on the effective number of light neutrinos ($\delta \mathit N_{{{\mathit \nu}}}$ $<~$1) and that  ${{\mathit \nu}_{{{R}}}}$ is light (${ {}\lesssim{} }~$1 MeV).
32  GRIFOLS 1990 limit holds for ${\mathit m}_{{{\mathit \nu}_{{{R}}}}}{ {}\lesssim{} }~$1 MeV. See also GRIFOLS 1990D, RIZZO 1991.
  References:
HERBERMANN 2025
JCAP 2509 078 Improved cosmological limits on $Z^\prime$ models with light right-handed neutrinos
AAD 2019L
PL B796 68 Search for high-mass dilepton resonances using 139 fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s}=$13 TeV with the ATLAS detector
BOBOVNIKOV 2018
PR D98 095029 Improved constraints on the mixing and mass of $Z'$ bosons from resonant diboson searches at the LHC at $\sqrt{s}=13$ TeV and predictions for Run II
AABOUD 2017AT
JHEP 1710 182 Search for New High-Mass Phenomena in the Dilepton Final State using 36 ${\mathrm {fb}}{}^{-1}$ of Proton-Proton Collision Data at $\sqrt {s }$ = 13 TeV with the ATLAS Detector
AABOUD 2016U
PL B761 372 Search for High-Mass New Phenomena in the Dilepton Final State using Proton-Proton Collisions at $\sqrt {s }$ = 13 TeV with the ATLAS Detector
AAD 2014V
PR D90 052005 Search for High-Mass Dilepton Resonances in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
AAD 2012CC
JHEP 1211 138 Search for High-Mass Resonances Decaying to Dilepton Final States in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV with the ATLAS Detector
AALTONEN 2011I
PRL 106 121801 Search for High Mass Resonances Decaying to Muon Pairs in $\sqrt {s }$ = 1.96 TeV ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions
ABAZOV 2011A
PL B695 88 Search for a Heavy Neutral Gauge Boson in the Dielectron Channel with 5.4 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 1.96$~$TeV
DEL-AGUILA 2010
JHEP 1009 033 Electroweak Limits on General New Vector Bosons
AALTONEN 2009T
PRL 102 031801 Search for High-Mass ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Resonances in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96$~$TeV
AALTONEN 2009V
PRL 102 091805 Search for High-Mass Resonances Decaying to Dimuons at CDF
ERLER 2009
JHEP 0908 017 Improved Constraints on ${{\mathit Z}^{\,'}}$ Bosons from Electroweak Precision Data
AALTONEN 2007H
PRL 99 171802 Search for New Physics in High-Mass Electron-Positron Events in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.96 TeV
SCHAEL 2007A
EPJ C49 411 Fermion Pair Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $189 - 209$ GeV and Constraints on Physics Beyond the Standard Model
ABDALLAH 2006C
EPJ C45 589 Measurement and Interpretation of Fermion-Pair Production at LEP Energies above the ${{\mathit Z}}$ Resonance
ABULENCIA 2006L
PRL 96 211801 Search for ${{\mathit Z}^{\,'}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ using Dielectron Mass and Angular Distribution
ABULENCIA 2005A
PRL 95 252001 Search for New High-Mass Particles Decaying to Lepton Pairs in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ =1.96 TeV
ABBIENDI 2004G
EPJ C33 173 Tests of the Standard Model and Constraints on New Physics from Measurements of Fermion Pair Production at 189 to 209 GeV at LEP
BARGER 2003B
PR D67 075009 Primordial Nucleosynthesis Constraints on ${{\mathit Z}^{\,'}}$ Properties
CHEUNG 2001B
PL B517 167 Constraints on Electron Quark Contact Interactions and Implications to Models of Leptoquarks and Extra ${{\mathit Z}}$ Bosons
ABREU 2000S
PL B485 45 Measurement and Interpretation of Fermion-Pair Production at LEP Energies of 183 and 189 GeV
BARATE 2000I
EPJ C12 183 Study of Fermion Pair Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $130 - 183$ GeV
CHO 2000
MPL A15 311 Looking for ${{\mathit Z}^{\,'}}$ Bosons in Supersymmetric E(6) Models Through Electroweak Precision Data
ERLER 2000
PRL 84 212 Indications for an Extra Neutral Gauge Boson in Electroweak Precision Data
ROSNER 2000
PR D61 016006 Atomic Parity Violation and Precision Electroweak Physics: An Updated Analysis
ERLER 1999
PL B456 68 Constraints on Extended Neutral Gauge Structures
CONRAD 1998
RMP 70 1341 Precision Measurements with High Energy Neutrino Beams
ABE 1997S
PRL 79 2192 Search for New Gauge Bosons Decaying into Dileptons in ${{\overline{\mathit p}}}$ ${{\mathit p}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
ARIMA 1997
PR D55 19 Precise Measurement of Bhabha Scattering at a Center-of-Mass Energy of 57.77 GeV
VILAIN 1994B
PL B332 465 Constraints on Additional ${{\mathit Z}}$ Bosons Derived from Neutrino Electron Scattering Measurements
FARAGGI 1991
MPL A6 61 A Superstring ${{\mathit Z}^{\,'}}$ at O(1 TeV)?
ABE 1990F
PL B246 297 Experimental Limits on Extra ${{\mathit Z}}$ Bosons from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ Annihilation Data with the VENUS Detector at $\sqrt {s }$ = 50-64 GeV
GONZALEZ-GARCIA 1990D
PL B240 163 Cosmological Constraints on Additional Light Neutrinos and Neutral Gauge Bosons
GRIFOLS 1990
NP B331 244 Implications from SN1987a on Supersymmetric, Left-Right and E(6) Particle Masses