title: Determination of the η(')-proton scattering length in free space.
abstract: Taking advantage of both the high mass resolution of the COSY-11 detector and the high energy resolution of the low-emittance proton beam of the cooler synchrotron COSY, we determine the excitation function for the pp→ppη(') reaction close to threshold. Combining these data with previous results, we extract the scattering length for the η(')-proton potential in free space to be Re(a(pη(')))=0±0.43  fm and Im(a(pη(')))=0.37(-0.16)(+0.40)  fm.
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Czerwiński
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: P
authors.initials: P
authors.lastname: Moskal
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Silarski
authors.affiliation: Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, A 1090 Vienna, Austria.
authors.forename: S D
authors.initials: SD
authors.lastname: Bass
authors.affiliation: Institute for Nuclear Physics and Jülich Center for Hadron Physics, Research Center Jülich, D-52425 Jülich, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Grzonka
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Kamys
authors.affiliation: IKP, Westfälische Wilhelms-Universität, D-48149 Münster, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Khoukaz
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Klaja
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: W
authors.initials: W
authors.lastname: Krzemień
authors.affiliation: Johannes Gutenberg-Universität Mainz, 550099 Mainz, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Oelert
authors.affiliation: Institute for Nuclear Physics and Jülich Center for Hadron Physics, Research Center Jülich, D-52425 Jülich, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ritman
authors.affiliation: Institute for Nuclear Physics and Jülich Center for Hadron Physics, Research Center Jülich, D-52425 Jülich, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Sefzick
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Smyrski
authors.affiliation: IKP, Westfälische Wilhelms-Universität, D-48149 Münster, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Täschner
authors.affiliation: Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Wolke
authors.affiliation: Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Zieliński