pdgLive

2017

LHCB

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit B}^{+}}{{\mathit X}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit K}^{+}}{{\mathit X}}$

$2982.8$ $\pm1.0$ $\pm0.5$

6.4k

2017

LHCB

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}{{\mathit X}}$ $\rightarrow$ 2( ${{\mathit K}^{+}}{{\mathit K}^{-}}$) ${{\mathit X}}$

$2982.2$ $\pm1.5$ $\pm0.1$

2.0k

⁴

2015

LHCB

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}$(1 ${{\mathit S}}$) ${{\mathit X}}$

$2983.5$ $\pm1.4$ ${}^{+1.6}_{-3.6}$

⁵

ANASHIN

KEDR

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

$2979.8$ $\pm0.8$ $\pm3.5$

4.5k

⁶ ^{, 7}

BABR

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \pi}^{0}}$

$2984.1$ $\pm1.1$ $\pm2.1$

900

⁶ ^{, 8}^{, 7}

BABR

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \eta}}$

$2984.3$ $\pm0.6$ $\pm0.6$

⁹ ^{, 10}

2012

BES3

${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

$2984.49$ $\pm1.16$ $\pm0.52$

832

⁶

2012

BES3

${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \gamma}}$ hadrons

$2982.7$ $\pm1.8$ $\pm2.2$

486

ZHANG

2012

BELL

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}{{\mathit \eta}^{\,'}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$

$2984.5$ $\pm0.8$ $\pm3.1$

11k

DEL-AMO-SANCH..

BABR

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$

$2985.4$ $\pm1.5$ ${}^{+0.5}_{-2.0}$

920

¹⁰

VINOKUROVA

BELL

${{\mathit B}^{\pm}}$ $\rightarrow$ ${{\mathit K}^{\pm}}$ ( ${{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit \pi}^{\mp}}$ )

$2982.2$ $\pm0.4$ $\pm1.6$

14k

¹¹

2010

BABR

10.6 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}{{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit \pi}^{\mp}}$

$2985.8$ $\pm1.5$ $\pm3.1$

0.9k

2008

BABR

${{\mathit B}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}{(1S)}}{{\mathit K}^{(*)}}$ $\rightarrow$ ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}{{\mathit K}^{(*)}}$

$2986.1$ $\pm1.0$ $\pm2.5$

7.5k

UEHARA

2008

BELL

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}$ $\rightarrow$ hadrons

$2970$ $\pm5$ $\pm6$

501

¹²

ABE

2007

BELL

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit J / \psi}}$( ${{\mathit c}}{{\overline{\mathit c}}}$)

$2971$ $\pm3$ ${}^{+2}_{-1}$

195

BELL

${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit K}^{+}}$

$2974$ $\pm7$ ${}^{+2}_{-1}$

BELL

${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\overline{\mathit \Lambda}}}{{\mathit K}^{+}}$

$2981.8$ $\pm1.3$ $\pm1.5$

592

ASNER

2004

CLEO

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}^{\,'}}$ $\rightarrow$ ${{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit \pi}^{\mp}}$

$2984.1$ $\pm2.1$ $\pm1.0$

190

¹³

AMBROGIANI

E835

${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$

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

$2982.5$ $\pm0.4$ $\pm1.4$

12k

¹⁴

DEL-AMO-SANCH..

BABR

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit \pi}^{\mp}}$

$2982.2$ $\pm0.6$

¹⁵

MITCHELL

2009

CLEO

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit X}}$

$2982$ $\pm5$

270

¹⁶

BABR

${{\mathit B}^{\pm}}$ $\rightarrow$ ${{\mathit K}^{\pm}}{{\mathit X}}$ $_{ {{\mathit c}} {{\overline{\mathit c}}} }$

$2982.5$ $\pm1.1$ $\pm0.9$

2.5k

¹⁷

2004

BABR

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}{(1S)}}$ $\rightarrow$ ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$

$2977.5$ $\pm1.0$ $\pm1.2$

¹⁸ ^{, 15}

BES

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

$2979.6$ $\pm2.3$ $\pm1.6$

180

¹⁹

FANG

BELL

${{\mathit B}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}{{\mathit K}}$

$2976.3$ $\pm2.3$ $\pm1.2$

²⁰ ^{, 15}

2000

BES

${{\mathit J / \psi}}$ , ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

$2976.6$ $\pm2.9$ $\pm1.3$

140

²¹ ^{, 15}

2000

BES

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

$2980.4$ $\pm2.3$ $\pm0.6$

²²

BRANDENBURG

2000

CLE2

${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit K}^{\pm}}{{\mathit K}_S^0}$ ${{\mathit \pi}^{\mp}}$

$2975.8$ $\pm3.9$ $\pm1.2$

²¹

1999

BES

Sup. by BAI 2000F

$2999$ $\pm8$

ABREU

1998

DLPH

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ +hadrons

$2988.3$ ${}^{+3.3}_{-3.1}$

ARMSTRONG

1995

E760

${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$

$2974.4$ $\pm1.9$

²³ ^{, 15}

BISELLO

1991

DM2

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}{{\mathit \gamma}}$

$2969$ $\pm4$ $\pm4$

¹⁵

1990

MRK3

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit K}^{+}}{{\mathit K}^{-}}$

$2956$ $\pm12$ $\pm12$

¹⁵

1990

MRK3

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit K}_S^0}$ ${{\mathit K}_L^0}$

$2982.6$ ${}^{+2.7}_{-2.3}$

BAGLIN

1987

SPEC

${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$

$2980.2$ $\pm1.6$

²³ ^{, 15}

MRK3

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}{{\mathit \gamma}}$

$2984$ $\pm2.3$ $\pm4.0$

¹⁵

GAISER

CBAL

${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}$ X, ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}$ X

$2976$ $\pm8$

²⁴ ^{, 15}

1984

MRK3

${{\mathit J / \psi}}$ $\rightarrow$ 2 ${{\mathit \phi}}{{\mathit \gamma}}$

$2982$ $\pm8$

²⁵

HIMEL

1980

MRK2

${{\mathit e}^{+}}{{\mathit e}^{-}}$

$2980$ $\pm9$

²⁵

PARTRIDGE

1980

CBAL

${{\mathit e}^{+}}{{\mathit e}^{-}}$

¹	AAIJ 2020H report ${\mathit m}_{{{\mathit J / \psi}}}–{\mathit m}_{{{\mathit \eta}_{{c}}{(1S)}}}$ = $113.0$ $\pm0.7$ $\pm0.1$ MeV. We use the current value ${\mathit m}_{{{\mathit J / \psi}}}$ = $3096.900$ $\pm0.006$ MeV to obtain the quoted mass.

²	AAIJ 2017AD report ${\mathit m}_{{{\mathit J / \psi}}}–{\mathit m}_{{{\mathit \eta}_{{c}}{(1S)}}}$ = $110.2$ $\pm0.5$ $\pm0.9$ MeV. We use the current value ${\mathit m}_{{{\mathit J / \psi}}}$ = $3096.900$ $\pm0.006$ MeV to obtain the quoted mass.

³	From a fit of the ${{\mathit \phi}}{{\mathit \phi}}$ invariant mass with the mass and width of ${{\mathit \eta}_{{c}}{(1S)}}$ as free parameters.

⁴

AAIJ 2015BI reports ${\mathit m}_{{{\mathit J / \psi}}}$ $−$ ${\mathit m}_{{{\mathit \eta}_{{c}}{(1S)}}}$ = $114.7$ $\pm1.5$ $\pm0.1$ MeV from a sample of ${{\mathit \eta}_{{c}}{(1S)}}$ and ${{\mathit J / \psi}}$ produced in ${{\mathit b}}$ -hadron decays. We have used current value of ${\mathit m}_{{{\mathit J / \psi}}}$ = $3096.900$ $\pm0.006$ MeV to arrive at the quoted ${\mathit m}_{{{\mathit \eta}_{{c}}{(1S)}}}$ result.

⁵	Taking into account an asymmetric photon lineshape.

⁶	With floating width.

⁷	Ignoring possible interference with the non-resonant 0${}^{-}$ amplitude.

⁸	Using both, ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ and ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ decays.

⁹	From a simultaneous fit to six decay modes of the ${{\mathit \eta}_{{c}}}$.

¹⁰	Accounts for interference with non-resonant continuum.

¹¹	Taking into account interference with the non-resonant $\mathit J{}^{P} = 0-$ amplitude.

¹²	From a fit of the ${{\mathit J / \psi}}$ recoil mass spectrum. Supersedes ABE,K 2002 and ABE 2004G.

¹³	Using mass of ${{\mathit \psi}{(2S)}}$ = $3686.00$ MeV.

¹⁴	Not independent from the measurements reported by LEES 2010 .

¹⁵

MITCHELL 2009 observes a significant asymmetry in the lineshapes of ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$ and ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$ transitions. If ignored, this asymmetry could lead to significant bias whenever the mass and width are measured in ${{\mathit \psi}{(2S)}}$ or ${{\mathit J / \psi}}$ radiative decays.

¹⁶	From the fit of the kaon momentum spectrum. Systematic errors not evaluated.

¹⁷	Superseded by LEES 2010 .

¹⁸	From a simultaneous fit of five decay modes of the ${{\mathit \eta}_{{c}}}$.

¹⁹	Superseded by VINOKUROVA 2011 .

²⁰	Weighted average of the ${{\mathit \psi}{(2S)}}$ and ${{\mathit J / \psi}{(1S)}}$ samples. Using an ${{\mathit \eta}_{{c}}}$ width of $13.2$ MeV.

²¹	Average of several decay modes. Using an ${{\mathit \eta}_{{c}}}$ width of $13.2$ MeV.

²²	Superseded by ASNER 2004 .

²³	Average of several decay modes.

²⁴	${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit \phi}}{{\mathit \phi}}$ .

²⁵	Mass adjusted by us to correspond to ${{\mathit J / \psi}{(1S)}}$ mass = 3097 MeV.

References:

2020H

EPJ C80 191

Measurement of the $\eta_c(1S)$ production cross-section in $pp$ collisions at $\sqrt{s} = 13$ TeV

2019AV

PR D100 052012

Observation of $\eta_c\to\omega\omega$ in $J/\psi\to\gamma\omega\omega$

2018

PR D98 072001

Measurement of eta_c(1S), eta_c(2S) and non-resonant eta' pi+ pi- production via two-photon collisions

2017AD

PL B769 305

Observation of ${{\mathit \eta}_{{c}}{(2S)}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}$ and Search for ${{\mathit X}{(3872)}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}$ Decays

2017BB

EPJ C77 609

Study of Charmonium Production in hadron Decays and First Evidence for the Decay ${{\mathit B}_{{s}}^{0}}$ $\rightarrow$ ${{\mathit \phi}}{{\mathit \phi}}{{\mathit \phi}}$

2015BI

EPJ C75 311

Measurement of the ${{\mathit \eta}_{{c}}{(1S)}}$ Production Cross-Section in Proton-Proton Collisions Via the Decay ${{\mathit \eta}_{{c}}{(1S)}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}$

ANASHIN

PL B738 391

Measurement of ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$ Decay Rate and ${{\mathit \eta}_{{c}}}$ Parameters at KEDR

2014E

PR D89 112004

Dalitz Plot Analysis of ${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \eta}}$ and ${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \pi}^{0}}$ in Two-Photon Interactions

2012N

PR D86 092009

Study of ${{\mathit \psi}{(3686)}}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit h}_{{c}}}$ , ${{\mathit h}_{{c}}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$ via ${{\mathit \eta}_{{c}}}$ Exclusive Decays

2012F

PRL 108 222002

Measurements of the Mass and Width of the ${{\mathit \eta}_{{c}}}$ Using the Decay ${{\mathit \psi}{(3686)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{c}}}$

ZHANG

2012A

PR D86 052002

First Study of ${{\mathit \eta}_{{c}}{(1S)}}$, ${{\mathit \eta}{(1760)}}$ and ${{\mathit X}{(1835)}}$ Production via ${{\mathit \eta}^{\,'}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ Final States in Two-Photon Collisions

DEL-AMO-SANCHEZ

2011M

PR D84 012004

Observation of ${{\mathit \eta}_{{c}}{(1S)}}$ and ${{\mathit \eta}_{{c}}{(2S)}}$ decays to ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ in Two-Photon Interactions

VINOKUROVA

PL B706 139

Study of ${{\mathit B}^{\pm}}$ $\rightarrow$ ${{\mathit K}^{\pm}}$ ($\mathit KSK{{\mathit \pi}}$) Decay and Determination of ${{\mathit \eta}_{{c}}}$ and ${{\mathit \eta}_{{c}}{(2S)}}$ Parameters

2010

PR D81 052010

Measurement of the ${{\mathit \gamma}}$ ${{\mathit \gamma}^{*}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}$ Transition Form Factor

MITCHELL

2009

PRL 102 011801

${{\mathit J / \psi}}$ and ${{\mathit \psi}{(2S)}}$ Radiative Decays to ${{\mathit \eta}_{{c}}}$

2008AB

PR D78 012006

Study of ${{\mathit B}}$-Meson Decays to ${{\mathit \eta}_{{c}}}{{\mathit K}^{(*)}}$ , ${{\mathit \eta}_{{c}}{(2S)}}{{\mathit K}^{(*)}}$ , and ${{\mathit \eta}_{{c}}}{{\mathit \gamma}}{{\mathit K}^{(*)}}$

UEHARA

2008

EPJ C53 1

Study of Charmonia in Four-Meson Final States Produced in Two-Photon Collisions

ABE

2007

PRL 98 082001

Observation of a Charmoniumlike State Produced in Association with ${{\mathit J / \psi}}$ in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at $\sqrt {s }$ $\sim{}$ 10.6 GeV

2006E

PRL 96 052002

Measurements of the Absolute Branching Fractions of ${{\mathit B}^{\pm}}$ $\rightarrow$ ${{\mathit K}^{\pm}}{{\mathit X}}$ $_{ {{\mathit c}} {{\overline{\mathit c}}} }$

PRL 97 162003

Study of ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}$ , ${{\mathit \Lambda}}{{\overline{\mathit \Lambda}}}$ and Observation of ${{\mathit \eta}_{{c}}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\overline{\mathit \Lambda}}}$ at Belle

ASNER

2004

PRL 92 142001

Observation of ${{\mathit \eta}_{{c}}^{\,'}}$ Production in ${{\mathit \gamma}}{{\mathit \gamma}}$ Fusion at CLEO

2004D

PRL 92 142002

Measurements of the Mass and Width of the ${{\mathit \eta}_{{c}}}$ Meson and of an ${{\mathit \eta}_{{c}}{(2S)}}$ Candidate

AMBROGIANI

PL B566 45

Measurement of the Resonance Parameters of the Charmonium Ground State, ${{\mathit \eta}_{{c}}}(1_{1}S_{0}$)

PL B555 174

Measurement of the Mass and Full Width of the ${{\mathit \eta}_{{c}}}$ Meson

FANG

PRL 90 071801

Measurement of Branching Fractions for ${{\mathit B}}$ $\rightarrow$ ${{\mathit \eta}_{{c}}}{{\mathit K}}{}^{(*)}$ Decays

2000F

PR D62 072001

A Measurement of the Mass and Full Width of the ${{\mathit \eta}_{{c}}}$ Meson

BRANDENBURG

2000B

PRL 85 3095

Measurements of the Mass, Total Width and Two Photon Partial Width of the ${{\mathit \eta}_{{c}}}$ Meson

1999B

PR D60 072001

Study of the Hadronic Decays of ${{\mathit \chi}_{{c}}}$ States

ABREU

1998O

PL B441 479

A Search for ${{\mathit \eta}_{{c}}^{\,'}}$ Production in Photon-Photon Fusion at LEP

ARMSTRONG

1995F

PR D52 4839

Study of the ${{\mathit \eta}_{{c}}}(1{}^{1}{{\mathit S}_{{0}}}$) State of Charmonium Formed in ${{\overline{\mathit p}}}{{\mathit p}}$ Annihilations and a Search for the ${{\mathit \eta}_{{c}}}(2{}^{1}{{\mathit S}_{{0}}}$)

BISELLO

1991

NP B350 1

Study of the ${{\mathit \eta}_{{c}}}$ Decays

1990B

PRL 65 1309

Observation of a Pseudoscalar State in ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \phi}}{{\mathit \phi}}$ near ${{\mathit \phi}}{{\mathit \phi}}$ Threshold

BAGLIN

1987B

PL B187 191

Direct Observation and Partial Width Measurement of ${{\mathit \gamma}}{{\mathit \gamma}}$ Decay of Charmonium States

PR D33 629

Hadronic Decay of the ${{\mathit \eta}_{{c}}{(2980)}}$

GAISER

PR D34 711

Charmonium Spectroscopy from Inclusive ${{\mathit \psi}^{\,'}}$ and ${{\mathit J / \psi}}$ Radiative Decays