Photoproduction of η mesons off protons forEγ⩽1.15GeV

Experimental study of the γp→π0ηp reaction with the A2 setup at the Mainz Microtron

“…So far, the unpolarized total and differential cross sections for π 0 η photoproduction on the free proton, as well as polarization observables with circularly and linearly polarized photon beams, were measured with the CBELSA/TAPS experimental setup at the ELSA accelerator [22][23][24], with the A2 setup at the MAMI accelerator [19][20][21], with the GRAAL detector at the ESRF accelerator [25], and at the LNS accelerator [26]. The unpolarized cross section and the beam-helicity asymmetry for photoproduction of π 0 η pairs on the deuteron and on helium nuclei have been recently published by the A2 collaboration [27].…”

ηproduction off the proton in a Regge-plus-chiral quark approach

“…The χ 2 dp value comes out smaller than 2 for data published between 1995 and 2007, by collaborations from MAMI [67] (MAMI95), LNS [20] (LNS06), and GRAAL [21] (GRAAL07). Those data span a total energy range going from threshold to W 1.9 GeV.…”

“…Differential cross section: The database includes 3349 data points for 1.5 W 2.8 GeV, coming from the following labs: MAMI [67], CLAS [18], ELSA [19], LNS [20], and GRAAL [21]. Only statistical uncertainties are used.…”

“…In the following we move to the observables for the γp → ηp and π − p → ηn processes, and we compare our results with [18], CLAS09 (filled diamonds) [24], LNS (filled squares) [20], GRAAL (open circles) [21], ELSA05 (filled circles) [19], ELSA09 (down triangles) [23], and MAMI (open triangles) [67]. the data.…”

“…The published CB data [17] are high-quality measurements, though limited to close to threshold kinematics. For the photoproduction process, a healthy amount of data has been published in recent years for both differential cross section [18][19][20][21] and polarized beam asymmetry [21,22]. Recently, CBELSA/TAPS [23] and CLAS [24] Collaborations released new data with higher precision and higher energies [24].…”