Electromagnetic Meson Production in the Nucleon Resonance Region
Recent experimental and theoretical advances in investigating electromagnetic meson production reactions in the nucleon resonance region are reviewed.
nucl-ex↗
arXiv subjects
V. D. Burkert
Publications and source records attributed to V. D. Burkert.
Measurement of the Proton Spin Structure Function $g_1(x,Q^2)$ for $Q^2$ from 0.15 to 1.6 GeV$^2$ with CLAS
Double-polarization asymmetries for inclusive $ep$ scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH$_3$ target in the CLAS detector. The polarized structure function $g_1(x,Q^2)$ was extracted throughout the nucleon resonance region and into the deep inelastic regime, for $Q^2 = 0.15 -1.64 $GeV$^2$. The contributions to the first moment $Γ_1(Q^2) = \int g_1(x,Q^2)dx$ were determined up to $Q^2=1.2$ GeV$^2$. Using a parametrization for $g_1$ in the unmeasured low $x$ regions, the complete first moment was estimated over this $Q^2$ region. A rapid change in $Γ_1$ is observed for $Q^2 < 1 $GeV$^2$, with a sign change near $Q^2 = 0.3 $GeV$^2$, indicating dominant contributions from the resonance region. At $Q^2=1.2$ GeV$^2$ our data are below the pQCD evolved scaling value.
nucl-ex↗
Measurement of $ep \to e^{'}pπ^{+}π^{-}$: experimental procedures and baryon resonance analysis
The cross section for the reaction $ e p \to e^{\prime} p π^{+} π^{-}$ was measured in the resonance region for 1.4$<$W$<$2.1 GeV and 0.5$<Q^{2}<$1.5 GeV$^{2}$/c$^{2}$ using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on $N^{*}$ and $Δ$ states shows an evident discrepancy. A better description of the data is obtained either by a sizeable change of the properties of the $P_{13}$(1720) resonance or by introducing a new baryon state, not reported in published analyses.
hep-ex↗
Single Quark Transition Model Analysis of Electromagnetic Nucleon Resonance Transitions in the [70,1-] Supermultiplet
We apply the single quark transition model to resonance transition amplitudes extracted from photo-and electroproduction data. We use experimental data on the S11(1535) and D13(1520) nucleon resonances to extract the amplitudes for the electromagnetic transition from the nucleon ground state to the [70,1-] SU(6)xO(3) supermultiplet, and make predictions for the transition amplitudes of all other states associated with the [70,1-]. We find suprisingly good agreement with the data.
hep-ph↗