Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus

Koshchii, Oleksandr; Roca-Maza, X.; Spiesberger, H.

doi:10.1103/physrevc.103.064316

Cited by 10 publications

(8 citation statements)

References 64 publications

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“…The significant disagreement between the measured value of beam normal SSA by the PREX collaboration [13] and the corresponding theoretical estimate [23] for heavier target nucleus 208 Pb raised questions about the calculations in general. More recently, Koshchii et al [24] calculated B n for electron scattering from several spin 0 nuclei, accounting for inelastic intermediate state contributions, in addition to several other improvements on the uncertainty calculation. However, the result does not resolve the discrepancy between the theoretical estimates and the PREX [13] data for a 208 Pb target nucleus.…”

Section: Introductionmentioning

confidence: 99%

Two-photon exchange from intermediate state resonances in elastic electron-proton scattering

Jaseer¹,

Blunden²,

Melnitchouk³

2020

Phys. Rev. C

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We calculate the beam (B n ) and target (A n ) normal single-spin asymmetries in electron-proton elastic scattering from two-photon exchange amplitudes with resonance intermediate states of spinparity 1/2 ± and 3/2 ± and mass W ≲ 1.8 GeV. The latest CLAS exclusive meson electroproduction data are used as input for the transition amplitudes from the proton to the excited resonance states.For B n , the spin 3/2 resonances dominate by an order of magnitude over the spin 1/2 states. In general we observe cancellations between the negative contributions of the ∆(1232) and N (1520) across both beam energy and scattering angle, and the positive contributions of the ∆(1700) and N (1720), leading to a rather large overall uncertainty band in the total B n . At forward angles and beam energies E lab < 1 GeV, where the ∆(1232) dominates, the calculated B n tend to overshoot the A4 and SAMPLE data. The calculated B n compare well with the measured values from the A4 and Q weak experiments with E lab > 1 GeV.

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Section: Introductionmentioning

confidence: 99%

Two-photon exchange from intermediate state resonances in elastic electron-proton scattering

Jaseer¹,

Blunden²,

Melnitchouk³

2020

Phys. Rev. C

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“…A correct understanding of the beam polarization is also crucial. In this respect, the analyzing power obtained in the PREX-2 experiment is quite puzzling [26][27][28]. At high incident electron-beam energies, inelastically scattered electrons from low-energy excited states or even from the giant dipole resonance of the studied target may impact results [2,29].…”

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confidence: 99%

Combined theoretical analysis of the parity-violating asymmetry for ${}^{48}$Ca and ${}^{208}Pb$

Reinhard¹,

Roca-Maza²,

Nazarewicz³

2022

Preprint

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The recent experimental determination of the parity violating asymmetry APV in 48 Ca and 208 Pb at Jefferson Lab is important for our understanding on how neutrons and protons arrange themselves inside the atomic nucleus. To better understand the impact of these measurements, we present a rigorous theoretical investigation of APV in 48 Ca and 208 Pb and assess the associated uncertainties. We complement our study by inspecting the static electric dipole polarizability in these nuclei. The analysis is carried out within nuclear energy density functional theory with quantified input. We conclude that the simultaneous accurate description of APV in 48 Ca and 208 Pb cannot be achieved by our models that accommodate a pool of global nuclear properties, such as masses and charge radii, throughout the nuclear chart, and describe --within one standard deviation-the experimental dipole polarizabilities αD in these nuclei.

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“…However, the measured asymmetry for 208 Pb was more than an order of magnitude smaller than predicted by this theory [2,5]. This discrepancy could not even be remedied by applying, instead of the second-order Born approximation, a nonperturbative treatment of the dispersion effects [8].…”

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confidence: 77%

Dispersion effects in elastic electron scattering from Pb208

Jakubassa-Amundsen,

Roca-Maza

2023

Phys. Rev. C

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Dispersion corrections to elastic electron scattering from 208 Pb at energies up to 150 MeV are estimated within the second-order Born approximation. All strong transient nuclear excited states with angular momentum up to L = 3 and natural parity are taken into consideration. It is found that at small scattering angles the high-lying L = 1 isovector states provide the dominant contribution to the dispersive change of the differential cross section and of the beam-normal spin asymmetry. At the back-most angles these changes are considerably smaller and are basically due to the isoscalar L = 2 and, to a lesser extent, L = 3 states. In comparison with the findings for 12 C, the dispersive cross-section modifications for 208 Pb are significantly larger, while the spin-asymmetry changes are much smaller at all angles. The latter originates from the destructive interference of the multipole contributions in 208 Pb that switch sign when proceeding from L to L + 1. This mechanism might be the origin of the small beam-normal spin asymmetries recently measured in 208 Pb at much larger energies.

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Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus

Cited by 10 publications

References 64 publications

Two-photon exchange from intermediate state resonances in elastic electron-proton scattering

Two-photon exchange from intermediate state resonances in elastic electron-proton scattering

Combined theoretical analysis of the parity-violating asymmetry for ${}^{48}$Ca and ${}^{208}Pb$

Dispersion effects in elastic electron scattering from Pb208

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