First extraction of the proton mass radius and scattering length $\left|α_{ρ^0 p}\right| $ from $ρ^0$ photoproduction

Abstract

As the lightest physical states excited from the vacuum by the scalar gluon, ρ 0 photoproduction is considered to be a suitable way to extract proton mass radius and scattering lengths of ρ 0 and proton interaction. In this work, under the assumption of the scalar form factor of dipole form, the value of proton mass radius is calculated as 0.86 ± 0.08 fm by fitting the differential cross section of γp → ρ 0 p reaction at near-threshold energy W = 1.78 GeV. Moreover, the ρ 0 -proton scattering lengths α ρ 0 p = 0.24 ± 0.02 fm is obtained for the first time within the vector meson dominance model. Correspondingly, the binding energy of ρ 0 in nuclear matter is calculated to be 23.6 MeV. These results may provide useful theoretical information for an in-depth understanding of proton structure and its interaction with vector mesons.

Research on proton mass radius and its mechanical properties via strange $ϕ$ meson photoproduction

“…At present, the proton mass radius value extracted by the cross section of heavy charmoniums photoproduction is roughly between 0.55 and 0.68 fm. In our recent work [53], the proton mass radius was 0.86 ± 0.08 fm extracted from the lighter ρ meson photoproduction data. Interestingly, the mass of φ is between the charmoniums and the ρ meson, and the corresponding proton mass radius value is also roughly in the middle.…”

“…[20]. The result of 0.67 ± 0.11 fm and 0.86 ± 0.08 fm are extraction from charmoniums photoproduction [21] and ρ photoproduction [53], respectively. 1.09 ± 0.07 Lattice QCD [6] 1.07 Holographic QCD [7] 0.963 DVCS [9] 1.01 ± 0.13 Light-front quark-diquark model [18] 1.37…”

“…. The result of 0.67 ± 0.11 fm and 0.86 ± 0.08 fm are extraction from charmoniums photoproduction[21] and ρ photoproduction[53], respectively.…”

Extraction of $ω$n, $ω$p and $ϕ$N scattering lengths from $ω$ and $ϕ$ differential photoproduction cross sections on the deuterium target

“…The ωp, φp, J/ψ − p, ψ(2S)p and ρ 0 p scattering lengths have been fully analysed in Refs. [2][3][4][5][6][7]. Based on the VMD model, the absolute value of the scattering length may be determined from the total near-threshold vector-meson photoproduction cross-section [1] or the differential crosssection of vector-meson photoproduction at threshold [8].…”

“…Great progress has been made in meson-proton scattering length measurements, but little is known about the vector meson-neutron scattering length. As the vector meson-proton scattering length has already been fixed by the data of ω, φ J/ψ, ψ(2S) and ρ 0 vector meson photoproductions near threshold in the previous analyses [3,[5][6][7][8]10], We want to try whether we can extract the vector meson-neutron scattering length using the deuterium target data that the neutron and the proton are loosely bound. The differential cross-section data of near-threshold ω and φ photoproductions on deuterium target were used for this analysis, including the incoherent photoproduction of vector meson (ω and φ vector mesons) [11,12] where the neutron or the proton is knocked out.…”