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${{\mathit W}}$ MASS

The ${{\mathit W}}$-mass listed here corresponds to the mass parameter in a Breit-Wigner distribution with mass-dependent width. To obtain the world averages of various measurements, common systematic uncertainties between experiments are evaluated and accounted for in combinations [SCHAEL 2013A, AMOROSO 2024].

Until 2022, the measurements of the ${{\mathit W}}$-boson mass at lepton and hadron colliders, LEP-2 (ALEPH, DELPHI, L3, and OPAL), Tevatron (CDF and D0), and LHC (ALEPH and LHCb), were in good agreement with each other [PDG 2022]. However, with the new CDF result [AALTONEN 2022] based on their complete Run-II data set, this is no longer the case.

The LHC-TeV MW Working Group, including ${{\mathit W}}$-mass experts from CDF, D0, ATLAS, CMS and LHCb [AMOROSO 2024], has examined this issue in depth. They report that a combination of all ${{\mathit W}}$-mass measurements corrected to a common theory description and PDF set, has a probability of compatibility of 0.5$\%$ only, and is therefore disfavoured. A 91$\%$ probability of compatibility is obtained when the CDF-II measurement is removed. The corresponding value of the ${{\mathit W}}$ boson mass is $80369.2$ $\pm13.3$ MeV, which we quote as the World Average.

More information is given in [M. Grunewald and A. Gurtu, �Mass and Width of the ${{\mathit W}}$ Boson� review, PDG 2024] and in [AMOROSO 2024].

VALUE (GeV)

EVTS

DOCUMENT ID

TECN

COMMENT

$\bf{ 80.3692 \pm0.0133}$

OUR EVALUATION (AMOROSO 2024)

$\bf{ 80.4335 \pm0.0094}$

(AALTONEN 2022 CDF)

$80.354$ $\pm0.023$ $\pm0.022$

2.4M

LHCB

${\it{}E}^{\it{}pp}_{\rm{}cm}$ = 13 TeV

$80.4335$ $\pm0.0064$ $\pm0.0069$

4.2M

CDF

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$80.370$ $\pm0.007$ $\pm0.017$

13.7M

ATLS

${\it{}E}^{\it{}pp}_{\rm{}cm}$ = 7 TeV

$80.375$ $\pm0.011$ $\pm0.020$

2177k

D0

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$80.336$ $\pm0.055$ $\pm0.039$

10.3k

DLPH

${\it{}E}^{\it{}ee}_{\rm{}cm}$ = $161 - 209$ GeV

$80.415$ $\pm0.042$ $\pm0.031$

11830

OPAL

${\it{}E}^{\it{}ee}_{\rm{}cm}$= $170 - 209$ GeV

$80.270$ $\pm0.046$ $\pm0.031$

9909

L3

${\it{}E}^{\it{}ee}_{\rm{}cm}$= $161 - 209$ GeV

$80.440$ $\pm0.043$ $\pm0.027$

8692

ALEP

${\it{}E}^{\it{}ee}_{\rm{}cm}$= $161 - 209$ GeV

$80.483$ $\pm0.084$

49247

D0

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= $1.8$ TeV

• • We do not use the following data for averages, fits, limits, etc. • •

$80.520$ $\pm0.070$ $\pm0.092$

H1

${{\mathit e}^{\pm}}{{\mathit p}}$

$80.387$ $\pm0.012$ $\pm0.015$

1095k

CDF

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$80.367$ $\pm0.013$ $\pm0.022$

1677k

D0

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$80.401$ $\pm0.021$ $\pm0.038$

500k

D0

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$80.413$ $\pm0.034$ $\pm0.034$

115k

CDF

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.96 TeV

$82.87$ $\pm1.82$ ${}^{+0.30}_{-0.16}$

1500

H1

${{\mathit e}^{\pm}}$ ${{\mathit p}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{{e}}}}({{\mathit \nu}_{{{e}}}}){{\mathit X}}$, $\sqrt {s }\approx{}$300 GeV

$80.3 \pm2.1 \pm1.2 \pm1.0$

645

ZEUS

${{\mathit e}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \nu}_{{{e}}}}$ X, $\sqrt {\mathit s }$= 318 GeV

$80.433$ $\pm0.079$

53841

CDF

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 1.8 TeV

$81.4 {}^{+2.7}_{-2.6} \pm2.0 {}^{+3.3}_{-3.0}$

1086

ZEUS

${{\mathit e}^{+}}$ ${{\mathit p}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{{e}}}}$ X, $\sqrt {\mathit s }\approx{}$ 300 GeV

$80.84$ $\pm0.22$ $\pm0.83$

2065

UA2

See ${{\mathit W}}/{{\mathit Z}}$ ratio below

$80.79$ $\pm0.31$ $\pm0.84$

UA2

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 546,630 GeV

$80.0$ $\pm3.3$ $\pm2.4$

22

CDF

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= $1.8$ TeV

$82.7$ $\pm1.0$ $\pm2.7$

149

UA1

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 546,630 GeV

$81.8$ ${}^{+6.0}_{-5.3}$ $\pm2.6$

46

UA1

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 546,630 GeV

$89$ $\pm3$ $\pm6$

32

UA1

${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 546,630 GeV

$81.$ $\pm5.$

6

UA1

${\it{}E}^{\it{}ee}_{\rm{}cm}$= $546$ GeV

$80$ ${}^{+10}_{-6}$

4

UA2

Repl. by ALITTI 1990B

¹

AAIJ 2022C analyse ${{\mathit W}}$ production in the muon decay channel, with the transverse momentum of the muon required to be between 28 and 52 GeV. Analysing the distribution of the muon charge divided by the muon transverse momentum of approximately 2.4 million selected ${{\mathit W}}$ candidates, a value of ${{\mathit M}_{{{W}}}}$ = $80354$ $\pm23$(stat.)$\pm10$(exp.)$\pm17$(theo.)$\pm9$(PDF) MeV is obtained; we combine the three systematic uncertainties in quadrature.

²

AALTONEN 2022 select a data sample of about 4 million ${{\mathit W}}$ boson candidates in 8.8 fb${}^{-1}$ of Run-II data. The mass is determined using the transverse mass, transverse lepton momentum and transverse missing momentum distributions of ${{\mathit W}}$ decays into electrons or muons, accounting for correlations. This measurement supersedes AALTONEN 2012E, but is not used in OUR EVALUATION.

³

AABOUD 2018J select 4.61M ${{\mathit W}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}$, 3.40M ${{\mathit W}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}$, 3.23M ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$ and 2.49M ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$ events in 4.6 fb${}^{-1}{{\mathit p}}{{\mathit p}}$ data at 7 TeV. The ${{\mathit W}}$ mass is determined using the transverse mass and transverse lepton momentum distributions, accounting for correlations. The systematic error includes 0.011 GeV experimental and 0.014 GeV modelling uncertainties.

⁴	Combination of results from ABAZOV 2012F and ABAZOV 2009AB as quoted in ABAZOV 2012F.

⁵

ABDALLAH 2008A use direct reconstruction of the kinematics of ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit \ell}}{{\mathit \nu}}$ and ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit q}}}$ events for energies 172 GeV and above. The ${{\mathit W}}$ mass was also extracted from the dependence of the ${{\mathit W}}{{\mathit W}}$ cross section close to the production threshold and combined appropriately to obtain the final result. The systematic error includes $\pm0.025$ GeV due to final state interactions and $\pm0.009$ GeV due to LEP energy uncertainty.

⁶

ABBIENDI 2006 use direct reconstruction of the kinematics of ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit \ell}}{{\mathit \nu}_{{{{{\mathit \ell}}}}}}$ and ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit q}}}$ events. The result quoted here is obtained combining this mass value with the results using ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit \ell}}{{\mathit \nu}_{{{{{\mathit \ell}}}}}}{{\mathit \ell}^{\,'}}{{\mathit \nu}}_{{{\mathit \ell}^{\,'}}}$ events in the energy range $183 - 207$ GeV (ABBIENDI 2003C) and the dependence of the $WW$ production cross-section on ${\mathit m}_{{{\mathit W}}}$ at threshold. The systematic error includes $\pm0.009$ GeV due to the uncertainty on the LEP beam energy.

⁷

ACHARD 2006 use direct reconstruction of the kinematics of ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit \ell}}{{\mathit \nu}_{{{{{\mathit \ell}}}}}}$ and ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit q}}}$ events in the C.M. energy range $189 - 209$ GeV. The result quoted here is obtained combining this mass value with the results obtained from a direct ${{\mathit W}}$ mass reconstruction at 172 and 183 GeV and with those from the dependence of the ${{\mathit W}}{{\mathit W}}$ production cross-section on ${\mathit m}_{{{\mathit W}}}$ at 161 and 172 GeV (ACCIARRI 1999).

⁸

SCHAEL 2006 use direct reconstruction of the kinematics of ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit \ell}}{{\mathit \nu}_{{{{{\mathit \ell}}}}}}$ and ${{\mathit W}^{+}}$ ${{\mathit W}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit q}}}$ events in the C.M. energy range $183 - 209$ GeV. The result quoted here is obtained combining this mass value with those obtained from the dependence of the ${{\mathit W}}$ pair production cross-section on ${\mathit m}_{{{\mathit W}}}$ at 161 and 172 GeV (BARATE 1997 and BARATE 1997S respectively). The systematic error includes $\pm0.009$ GeV due to possible effects of final state interactions in the ${{\mathit q}}{{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit q}}}$ channel and $\pm0.009$ GeV due to the uncertainty on the LEP beam energy.

⁹

ABAZOV 2002D improve the measurement of the ${{\mathit W}}$-boson mass including ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}_{{{e}}}}$ events in which the electron is close to a boundary of a central electromagnetic calorimeter module. Properly combining the results obtained by fitting $\mathit m_{\mathit T}({{\mathit W}}$), $\mathit p_{\mathit T}({{\mathit e}}$), and $\mathit p_{\mathit T}({{\mathit \nu}}$), this sample provides a mass value of $80.574$ $\pm0.405$ GeV. The value reported here is a combination of this measurement with all previous ${D0}{{\mathit W}}$-boson mass measurements.

¹⁰

ANDREEV 2018A obtain this result in a combined electroweak and QCD analysis using all deep-inelastic ${{\mathit e}^{+}}{{\mathit p}}$ and ${{\mathit e}^{-}}{{\mathit p}}$ neutral current and charged current scattering cross sections published by the H1 Collaboration, including data with longitudinally polarized lepton beams.

¹¹

AALTONEN 2012E select 470k ${{\mathit W}}$ ${{\mathit \nu}}$ decays and 625k ${{\mathit W}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}}$ decays in 2.2 fb${}^{-1}$ of Run-II data. The mass is determined using the transverse mass, transverse lepton momentum and transverse missing energy distributions, accounting for correlations. This result supersedes AALTONEN 2007F. AALTONEN 2014D gives more details on the procedures followed by the authors. This measurement is superseded by AALTONEN 2022.

¹²	ABAZOV 2012F select 1677k ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}$ decays in 4.3 fb${}^{-1}$ of Run-II data. The mass is determined using the transverse mass and transverse lepton momentum distributions, accounting for correlations.

¹³	ABAZOV 2009AB study the transverse mass, transverse electron momentum, and transverse missing energy in a sample of 0.5 million ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}$ decays selected in Run-II data. The quoted result combines all three methods, accounting for correlations.

¹⁴

AALTONEN 2007F obtain high purity ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}_{{{e}}}}$ and ${{\mathit W}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}_{{{\mu}}}}$ candidate samples totaling 63,964 and 51,128 events respectively. The ${{\mathit W}}$ mass value quoted above is derived by simultaneously fitting the transverse mass and the lepton, and neutrino p$_{T}$ distributions.

¹⁵	AKTAS 2006 fit the Q${}^{2}$ dependence (300 $<$ Q${}^{2}$ $<$ 30,000 GeV${}^{2}$) of the charged-current differential cross section with a propagator mass. The first error is experimental and the second corresponds to uncertainties due to input parameters and model assumptions.

¹⁶	CHEKANOV 2002C fit the $\mathit Q{}^{2}$ dependence (200$<\mathit Q{}^{2}<$60000 GeV${}^{2}$) of the charged-current differential cross sections with a propagator mass fit. The last error is due to the uncertainty on the probability density functions.

¹⁷

AFFOLDER 2001E fit the transverse mass spectrum of 30115 ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}_{{{e}}}}$ events ($\mathit M_{{{\mathit W}}}$= $80.473$ $\pm0.065$ $\pm0.092$ GeV) and of 14740 ${{\mathit W}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}_{{{\mu}}}}$ events ($\mathit M_{{{\mathit W}}}$= $80.465$ $\pm0.100$ $\pm0.103$ GeV) obtained in the run IB (1994-95). Combining the electron and muon results, accounting for correlated uncertainties, yields $\mathit M_{{{\mathit W}}}$= $80.470$ $\pm0.089$ GeV. They combine this value with their measurement of ABE 1995P reported in run IA (1992-93) to obtain the quoted value.

¹⁸	BREITWEG 2000D fit the $\mathit Q{}^{2}$ dependence (200 $<$ Q${}^{2}<$ 22500 GeV${}^{2}$) of the charged-current differential cross sections with a propagator mass fit. The last error is due to the uncertainty on the probability density functions.

¹⁹

ALITTI 1992B result has two contributions to the systematic error ($\pm0.83$); one ($\pm0.81$) cancels in ${\mathit m}_{{{\mathit W}}}/{\mathit m}_{{{\mathit Z}}}$ and one ($\pm0.17$) is noncancelling. These were added in quadrature. We choose the ALITTI 1992B value without using the LEP ${\mathit m}_{{{\mathit Z}}}$ value, because we perform our own combined fit.

²⁰	There are two contributions to the systematic error ($\pm0.84$): one ($\pm0.81$) which cancels in ${\mathit m}_{{{\mathit W}}}/{\mathit m}_{{{\mathit Z}}}$ and one ($\pm0.21$) which is non-cancelling. These were added in quadrature.

²¹	ABE 1989I systematic error dominated by the uncertainty in the absolute energy scale.

²²	ALBAJAR 1989 result is from a total sample of 299 ${{\mathit W}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}$ events.

²³	ALBAJAR 1989 result is from a total sample of 67 ${{\mathit W}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}}$ events.

²⁴	ALBAJAR 1989 result is from ${{\mathit W}}$ $\rightarrow$ ${{\mathit \tau}}{{\mathit \nu}}$ events.

Except where otherwise noted, content of the 2024 Review of Particle Physics is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT (Japan), INFN (Italy) and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2024. See LBNL disclaimers.