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${{\mathit \eta}_{{{c}}}{(1S)}}$ MASS

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M026M

VALUE (MeV) EVTS DOCUMENT ID TECN  COMMENT $\bf{ 2984.1 \pm0.4}$ OUR AVERAGE  Error includes scale factor of 1.2. $2985.01$ $\pm0.17$ $\pm0.89$ 35k AAIJ 2023 AH LHCB ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit K}^{+}}$( ${{\mathit K}_S^0}$ ${{\mathit K}}{{\mathit \pi}}$) $2983.9$ $\pm0.7$ $\pm0.1$ 1 AAIJ 2020 H LHCB ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit b}}{{\mathit X}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit X}}$ $2985.9$ $\pm0.7$ $\pm2.1$ 1705 ABLIKIM 2019 AV BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \omega}}{{\mathit \omega}}$ $2984.6$ $\pm0.7$ $\pm2.2$ 2673 XU 2018 BELL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}{{\mathit \eta}^{\,'}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ $2986.7$ $\pm0.5$ $\pm0.9$ 11k 2 AAIJ 2017 AD 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 3 AAIJ 2017 BB 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 AAIJ 2015 BI LHCB ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}_{{{c}}}}$(1 ${{\mathit S}}$) ${{\mathit X}}$ $2983.5$ $\pm1.4$ ${}^{+1.6}_{-3.6}$ 5 ANASHIN 2014 KEDR ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{{c}}}}$ $2979.8$ $\pm0.8$ $\pm3.5$ 4.5k 6, 7 LEES 2014 E BABR ${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \pi}^{0}}$ $2984.1$ $\pm1.1$ $\pm2.1$ 900 6, 8, 7 LEES 2014 E BABR ${{\mathit \gamma}}$ ${{\mathit \gamma}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit \eta}}$ $2984.3$ $\pm0.6$ $\pm0.6$ 9, 10 ABLIKIM 2012 F BES3 ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{{c}}}}$ $2984.49$ $\pm1.16$ $\pm0.52$ 832 6 ABLIKIM 2012 N BES3 ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \gamma}}$ hadrons $2982.7$ $\pm1.8$ $\pm2.2$ 486 ZHANG 2012 A 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.. 2011 M 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 2011 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 LEES 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 AUBERT 2008 AB 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 WU 2006 BELL ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\overline{\mathit p}}}{{\mathit K}^{+}}$ $2974$ $\pm7$ ${}^{+2}_{-1}$ 20 WU 2006 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 2003 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.. 2011 M 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 AUBERT 2006 E BABR ${{\mathit B}^{\pm}}$ $\rightarrow$ ${{\mathit K}^{\pm}}{{\mathit X}}_{{{\mathit c}} {{\overline{\mathit c}}}}$ $2982.5$ $\pm1.1$ $\pm0.9$ 2.5k 17 AUBERT 2004 D 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 BAI 2003 BES ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{{c}}}}$ $2979.6$ $\pm2.3$ $\pm1.6$ 180 19 FANG 2003 BELL ${{\mathit B}}$ $\rightarrow$ ${{\mathit \eta}_{{{c}}}}{{\mathit K}}$ $2976.3$ $\pm2.3$ $\pm1.2$ 20, 15 BAI 2000 F BES ${{\mathit J / \psi}}$ , ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{{c}}}}$ $2976.6$ $\pm2.9$ $\pm1.3$ 140 21, 15 BAI 2000 F BES ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}_{{{c}}}}$ $2980.4$ $\pm2.3$ $\pm0.6$ 22 BRANDENBURG 2000 B 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 BAI 1999 B BES Sup. by BAI 2000F $2999$ $\pm8$ 25 ABREU 1998 O DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ +hadrons $2988.3$ ${}^{+3.3}_{-3.1}$ ARMSTRONG 1995 F E760 ${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ $2974.4$ $\pm1.9$ 23, 15 BISELLO 1991 DM2 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \eta}_{{{c}}}}{{\mathit \gamma}}$ $2969$ $\pm4$ $\pm4$ 80 15 BAI 1990 B MRK3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit K}^{+}}{{\mathit K}^{-}}$ $2956$ $\pm12$ $\pm12$ 15 BAI 1990 B MRK3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}^{+}}{{\mathit K}^{-}}{{\mathit K}_S^0}$ ${{\mathit K}_L^0}$ $2982.6$ ${}^{+2.7}_{-2.3}$ 12 BAGLIN 1987 B SPEC ${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ $2980.2$ $\pm1.6$ 23, 15 BALTRUSAITIS 1986 MRK3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \eta}_{{{c}}}}{{\mathit \gamma}}$ $2984$ $\pm2.3$ $\pm4.0$ 15 GAISER 1986 CBAL ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}$ X, ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}$ X $2976$ $\pm8$ 24, 15 BALTRUSAITIS 1984 MRK3 ${{\mathit J / \psi}}$ $\rightarrow$ 2 ${{\mathit \phi}}{{\mathit \gamma}}$ $2982$ $\pm8$ 18 25 HIMEL 1980 B MRK2 ${{\mathit e}^{+}}{{\mathit e}^{-}}$ $2980$ $\pm9$ 25 PARTRIDGE 1980 B 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.

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