Measurement of the Transverse-Longitudinal Cross Sections in the p (e,e'p)pi0 Reaction in the Delta Region

Abstract

Accurate measurements of the p(e,e?p)pi0 reaction were performed at Q^2=0.127(GeV/c)^2 in the Delta resonance energy region. The experiments at the MIT-Bates Linear Accelerator used an 820 MeV polarized electron beam with the out of plane magnetic spectrometer system (OOPS). In this paper we report the first simultaneous determination of both the TL and TL? (``fifth" or polarized) cross sections at low Q^{2} where the pion cloud contribution dominates the quadrupole amplitudes (E2 and C2). The real and imaginary parts of the transverse-longitudinal cross section provide both a sensitive determination of the Coulomb quadrupole amplitude and a test of reaction calculations. Comparisons with model calculations are presented. The empirical MAID calculation gives the best overall agreement with this accurate data. The parameters of this model for the values of the resonant multipoles are |M_{1+}(I=3/2)|= (40.9 \pm 0.3)10^{-3}/m_pi, CMR= C2/M1= -6.5 \pm 0.3%, EMR=E2/M1=-2.2 \pm 0.9%, where the errors are due to the experimental uncertainties.

10 pages, 3 figures, minor corrections and additions

References in corpus (13)

• A unitary isobar model for pion photo- and electroproduction on the proton up to 1 GeV
• $Q^2$ Dependence of Quadrupole Strength in the ${\gamma }^{\ast }p\to {\Delta }^{+}(1232)\to p{\pi }^0$ Transition
• Dynamical Study of the Delta Excitation in N(e,e' pi) Reactions
• Pion cloud and the $Q^2-$dependence of ${\gamma }^{\ast }N\leftrightarrow \Delta$ transition form factors
• Multipole analysis of pion photoproduction based on fixed t dispersion relations and unitarity
• Determination of the E2/M1 Ratio in the γN \to Δ(1232) Transition from a Simultaneous Measurement of p(\vecγ,p)π^0 and p(\vecγ,π^+)n
• Search for Quadrupole Strength in the Electro-excitation of the Delta(1232)
• Measurement of the recoil polarization in the p (\vec e, e' \vec p) pi^0 reaction at the Δ(1232) resonance
• Measurement of the beam-helicity asymmetry in the p(e_pol,e'p)pi_0 reaction at the energy of the Delta(1232) resonance
• The role of the pion cloud in electroproduction of the $\Delta$(1232)
• Induced proton polarization for pi^0 electroproduction at Q^2 = 0.126 (GeV/c)^2 around the Delta(1232) resonance
• How to extract the P_{33}(1232) resonance contributions from the amplitudes M_{1+}^{3/2},E_{1+}^{3/2},S_{1+}^{3/2} of pion electroproduction on nucleons
• A polarization relation and the measurement of the longitudinal response in pseudoscalar meson electroproduction off the nucleon

Cited by in corpus (33)

• Electromagnetic excitation of the Delta(1232)-resonance
• Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
• Electroexcitation of nucleon resonances
• Electromagnetic Meson Production in the Nucleon Resonance Region
• Investigation of the conjectured nucleon deformation at low momentum transfer
• Chiral Effective-Field Theory in the Delta(1232) Region: Pion Electroproduction on the Nucleon
• Extraction and Interpretation of gamma N --> Delta Form Factors within a Dynamical Model
• Electromagnetic Nucleon-to-Delta Transition in Chiral Effective-Field Theory
• Nucleon electromagnetic form factors and electroexcitation of low lying nucleon resonances in a light-front relativistic quark model
• Recoil Polarization for Delta Excitation in Pion Electroproduction
• Measurement of the Polarized Structure Function ${\sigma }_{L{T}^{\prime }}$ for $p(\vec{e},e^{\prime }p){\pi }^o$ in the $\Delta (1232)$ Resonance Region
• Lowest Q^2 Measurement of the gamma*p -> Delta Reaction: Probing the Pionic Contribution
• Measurement of the Polarized Structure Function ${\sigma }_{L{T}^{\prime }}$ for $p(\vec{e},e^{\prime }{\pi }^{+})n$ in the $\Delta (1232)$ Resonance Region
• Determination of quadrupole strengths in the gamma*p-->Delta(1232) transition at Q2= 0.20 (GeV/c)2
• Hadron structure at low Q^2
• Measurements of the gamma*p->Delta Reaction At Low Q^2: Probing the Mesonic Contribution
• Jülich-Bonn-Washington Model for Pion Electroproduction Multipoles
• Recoil Polarization Measurements for Neutral Pion Electroproduction at Q^2=1 (GeV/c)^2 Near the Delta Resonance
• Electromagnetic Transition Form Factors of Baryon Resonances
• Dynamical Models of the Excitations of Nucleon Resonances
• Electroexcitation of nucleon resonances of the [70,1-] multiplet in a light-front relativistic quark model
• Study of nucleon resonances with electromagnetic interactions
• Coupled-channel analysis of pion- and eta-electroproduction with the Jülich-Bonn-Washington model
• Measurements of the γ* p --> Δ(1232) reaction at low Q2
• Electroexcitation of the ${\Delta }^{+}(1232)$ at low momentum transfer
• Electroexcitation of the Delta(1232)3/2+ and Delta(1600)3/2+ in a light-front relativistic quark model
• Virtual Compton Scattering measurements in the ${\gamma }^{\ast }N\to \Delta$ transition
• The Delta(1232) Resonance in Chiral Effective Field Theory
• Light-cone sum rules for the $N\gamma \Delta$ transitions for real photons
• Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model
• Measurement of the Partial Cross Sections s(TT), s(LT) and [s(T)+epsilon*s(L)] of the p(e,e' pi+)n Reaction in the Delta(1232) Resonance
• Pion electroproduction measurements in the nucleon resonance region
• Two-photon physics