@article{67ff3afbb89c4305a4e731a2266f5f98,
title = "Measurement of ηc (1S), ηc (2S), and nonresonant η′π+π- production via two-photon collisions",
abstract = "We report the measurement of γγ→ηc(1S),ηc(2S)→η′π+π- with η′ decays to γρ and ηπ+π- using 941 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The ηc(1S) mass and width are measured to be M=[2984.6±0.7 (stat)±2.2 (syst)±0.3 (model)] MeV/c2 and Γ=[30.8-2.2+2.3 (stat)±2.5 (syst)±1.4 (model)] MeV, respectively. First observation of ηc(2S)→η′π+π- with a significance of 5.5σ including systematic error is obtained, and the ηc(2S) mass is measured to be M=[3635.1±3.7 (stat)±2.9 (syst)±0.4 (model)] MeV/c2. The products of the two-photon decay width and branching fraction (B) of decays to η′π+π- are determined to be ΓγγΓγγB=[65.4±2.6 (stat)±7.8 (syst)] eV for ηc(1S) and [5.6-1.1+1.2 (stat)±1.1 (syst)] eV for ηc(2S). The cross sections for γγ→η′π+π- and η′f2(1270) are measured for the first time.",
author = "{LHCb Collaboration} and Xu, {Q. N.} and I. Adachi and H. Aihara and {Al Said}, S. and Asner, {D. M.} and H. Atmacan and V. Aulchenko and T. Aushev and R. Ayad and V. Babu and I. Badhrees and Bakich, {A. M.} and V. Bansal and E. Barberio and P. Behera and M. Berger and V. Bhardwaj and B. Bhuyan and J. Biswal and A. Bondar and A. Bozek and M. Bra{\v c}ko and D. {\v C}ervenkov and A. Chen and Cheon, {B. G.} and K. Chilikin and K. Cho and Choi, {S. K.} and Y. Choi and D. Cinabro and S. Cunliffe and T. Czank and N. Dash and {Di Carlo}, S. and Z. Dole{\v Z}al and Z. Dr{\'a}sal and S. Eidelman and D. Epifanov and Fast, {J. E.} and T. Ferber and Fulsom, {B. G.} and R. Garg and V. Gaur and N. Gabyshev and A. Garmash and M. Gelb and P. Goldenzweig and Y. Guan and E. Guido and Kim, {H. J.}",
note = "Publisher Copyright: {\textcopyright} 2018 authors. Published by the American Physical Society.",
year = "2018",
month = oct,
day = "1",
doi = "10.1103/PhysRevD.98.072001",
language = "English",
volume = "98",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "7",
}