Erratum to: “Analysing power Ay in the reaction p→p→ppη close to threshold”

First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

“…along the y acc axis. Denoting by N(θ η , φ η ) 1 the number of the η mesons emitted into the solid angle around θ η and φ η and by N 1 and N 2 the numbers of the η mesons reaching the virtual η "detectors" 1 and 2 we can write: 15) and 16) where the symbol "↑" stands for the spin up orientation, L ↑ dt is the luminosity during the measurement with spin up, integrated over the whole time of the measurement, E(θ η , φ η ) is the efficiency of the detection setup for "registering" the η mesons produced into the solid angle around θ η and φ η , σ 0 (θ η ) is the cross section for the η meson production with absence of the beam polarisation, P ↑ is the beam polarisation during the spin up cycles and A y (θ η ) is the analysing power for the η production averaged over m pp , m pη and ψ. The "+" sign denotes the production with the polarisation vector along the Oy M -axis (according to the Madison convention P y is positive in this case), and the "−" sign is for the production with the polarisation vector antiparallel to the Oy M -axis (negative P y ).…”

“…After early measurements of the total cross sections for the pp → ppη reaction in bubble chamber experiments [31][32][33][34][35][36][37][38], only recently there appeared high-statistics, close-to-threshold data from storage rings, giving opportunity to investigate more accurately the structure, properties, production mechanism as well as the interaction of the η meson with hadronic matter. The close-to-threshold total cross section measurements for the pp → ppη reaction [2][3][4][5][6][7][8][9][10], investigations on the differential cross sections for this reaction [8,12,[39][40][41] and recently performed measurements of the analysing power for the pp → ppη reaction [15,16] made the theoretical analysis possible aiming in understanding the production process.…”

“…Here the measurements of the polarisation observables can assist, because the predictions of the one boson exchange models [11,14] with respect to the most Introduction basic polarisation observable as the analysing power are sensitive to the type of meson being exchanged between the protons in order to excite one of them into the resonant state. Measurements of the beam analysing power for the pp → ppη reaction performed by the DISTO collaboration [15] as well as the tentative experiment of the COSY-11 group [16,17] did not bring the univocal solution of this problem. The interpretation of results of the DISTO measurements, performed in the far-from-threshold region at the excess energies of Q = 324, 412, and 554 MeV suffered from the lack of a theoretical prediction for the analysing power.…”

Summary of studies of the η meson production with polarized proton beam at COSY-11

“…The method of the analysis and the results have been reported in [14]. The method of the analysis and the results have been reported in [14].…”

Study of the $\eta $-Meson Production with Polarized Proton Beam

“…This may be at least to some extent achieved by the measurement of the analyzing power A y which would enable to perform the partial wave decomposition with an accuracy by far better than resulting from the measurements of the distributions of the spin averaged cross sections. Up to now, measurements of the analyzing power for the pp → ppη reaction were performed by the COSY-11 and DISTO collaborations [48][49][50][51]. Due to the lack of statistics and small detector acceptance (in case of COSY-11 [52,53]) these first measurements did not allow for unambiguous conclusions about the production mechanisms.…”