Comparison of optical potential for nucleons and $$\varDelta $$ resonances

Abstract

Precise modeling of neutrino interactions on nuclear targets is essential for neutrino oscillations experiments. The modeling of the energy of final state particles in quasielastic (QE) scattering and resonance production on bound nucleons requires knowledge of both the removal energy of the initial state bound nucleon as well as the average Coulomb and nuclear optical potentials for final state leptons and hadrons. We extract the average values of the real part of the nuclear optical potential for final state nucleons ($$U_{opt}^{QE}$$ U opt QE ) as a function of the nucleon kinetic energy from inclusive electron scattering data on nuclear targets ($$_\mathbf{6 }^\mathbf{12 }{} \mathbf{C} $$ 6 12 C +$$_\mathbf{8 }^\mathbf{16 }{} \mathbf{O} $$ 8 16 O , $$_\mathbf{20 }^\mathbf{40 }{} \mathbf{Ca} $$ 20 40 Ca +$$_\mathbf{18 }^\mathbf{40 }{} \mathbf{Ar} $$ 18 40 Ar , $$_\mathbf{3 }^\mathbf{6 }{} \mathbf{Li} $$ 3 6 Li , $$_\mathbf{18 }^\mathbf{27 }{} \mathbf{Al} $$ 18 27 Al , $$_\mathbf{26 }^\mathbf{56 }{} \mathbf{Fe} $$ 26 56 Fe , $$_\mathbf{82 }^\mathbf{208 }{} \mathbf{Pb} $$ 82 208 Pb ) in the QE region and compare to calculations. We also extract values of the average of the real part of the nuclear optical potential for a $$\varDelta (1232)$$ Δ ( 1232 ) resonance in the final state ($$U^\varDelta _{opt}$$ U opt Δ ) within the impulse approximation. We find that $$U^\varDelta _{opt}$$ U opt Δ is more negative than $$U_{opt}^{QE}$$ U opt QE with $$U^\varDelta _{opt}\approx $$ U opt Δ ≈ 1.5 $$U_{opt}^{QE}$$ U opt QE for $$_\mathbf{6 }^\mathbf{12 }{} \mathbf{C} $$ 6 12 C .

Assessing the accuracy of the GENIE event generator with electron-scattering data

“…First of all, these large percentage discrepancies often arise in the regions where the absolute rates are small. Second, the agreement can be improved by a subtle shift of the peak and [49,50] other adjustments [68], which are well understood theoretically [42]. Below momentum transfer values jqj ∼ 0.8 GeV, and above jqj ∼ 3 GeV, the QE electron scattering rate predicted by GENIE does show significant discrepancies from the data.…”

In-medium $Δ(1232)$ potential, pion production in heavy-ion collisions and the symmetry energy

“…In Ref. [47] the strength of the DPOT was extracted from the study of experimental data of quasi-elastic scattering of electrons on bound nucleons in nuclei of different masses: 6 Li, 12 C, 27 Al, 40 Ca/Ar and 56 Fe. It was found that the DPOT is more attractive than the empirical nucleon optical potential and the attraction is stronger for heavier nuclei reflecting higher probed densities.…”

“…The knowledge of the isoscalar ∆ (1232) potential (ISDP) is uncertain, with empirical information contradicting microscopical calculations [46,47,48,49,50,51,52,53]. Discrepancies among results of microscopical models have also been noted and are often related to details of how pionnucleon and pion-nucleon-delta couplings have been extracted from few-body experimental data.…”

“…No information is avaiblable about the isovector component of the ∆ (1232) potential (IVDP). These quantities are also relevant for determining the threshold density above which ∆ (1232) occurs in neutron stars, with impact on the maximum mass of such objects [54,55,56,57,58] and in the analysis of neutrino physics experimental data [47].…”

Simultaneous measurement of proton and lepton kinematics in quasielastic-like $ν_μ$-hydrocarbon interactions from 2 to 20 GeV

“…2 also suggests, would improve agreement with this data. Shifts in energy transfers have been observed in (e,e') data for regions of low energy transfer [34,[60][61][62][63][64][65][66][67][68]. An over-prediction of pion FSI could arise from finite hadronic formation time [69], an effect not included in the reference simulation.…”