Compton scattering from the deuteron below pion-production threshold

Myers, L. S.; Annand, J. R. M.; Brudvik, J.; Feldman, G.; Fissum, Kevin; Grießhammer, Harald W.; Hansen, Kurt Schaldemose; Henshaw, S. S.; Isaksson, L.; Jebali, R. Al; Kovash, M. A.; Lundin, Magnus; Middleton, D. G.; Nathan, Alan M.; Schrøder, B.; Stave, S.

doi:10.1103/physrevc.92.025203

Cited by 22 publications

(19 citation statements)

References 34 publications

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“…A detailed discussion of the uncertainties, as well as the cross sections, can be found in Ref. [32]. For the first data-production run, correlated systematic uncertainties add in quadrature to 5.2%; and for the second run, they add to 4.7%.…”

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confidence: 99%

Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities

et al. 2014

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The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data-and have been, with good accuracy, in the case of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world dataset. Their energy range overlaps with previous experiments and extends it by 20 MeV to higher energies. An analysis using Chiral Effective Field Theory with dynamical ∆(1232) degrees of freedom shows the data are consistent with and within the world dataset. After demonstrating that the fit is consistent with the Baldin sum rule, extracting values for the isoscalar nucleon polarizabilities and combining them with a recent result for the proton, we obtain the neutron polarizabilities as αn = [11.55 ± 1.25(stat) ± 0.2(BSR) ± 0.8(th)] × 10 −4 fm 3 and βn = [3.65 ∓ 1.25(stat) ± 0.2(BSR) ∓ 0.8(th)] × 10 −4 fm 3 , with χ 2 = 45.2 for 44 degrees of freedom.

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Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities

et al. 2014

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“…Once data are available, a polarisability extraction will of course need to address residual theoretical uncertainties with more diligence, as was already done for the proton and deuteron in refs. [21,31,32,40,41].…”

Section: A Note On Estimates Of Theory Uncertaintiesmentioning

confidence: 99%

“…Still, relative to the deuteron, 3 He data offers the promise of stronger signals and of crossvalidation of the theory used to subtract binding effects and extract nucleon polarisabilities. 1 Most recently, Myers et al [31,32] measured the differential cross section on the deuteron at energies ranging from 65 to 115 MeV, doubling the world data for elastic γd scattering. In combination with the proton results quoted below, a fit using the χEFT γd amplitude at the same order, O(e 2 δ 3 ), as the current work, yields α (n) E1 = 11.55 ± 1.25(stat.)…”

Section: Introductionmentioning

confidence: 99%

“…In this presentation, we therefore examine the influence of the Delta on the cross section and asymmetries, using the same photonuclear kernel as in the extraction of the scalar polarisabilities of the neutron from γd data, eq. (1.1) [31,32,40]. The Delta degree of freedom plays a significant role in some of the spin polarisabilities, especially in γ M 1M 1 .…”

Section: Introductionmentioning

confidence: 99%

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Elastic Compton scattering from 3He and the role of the Delta

et al. 2018

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We report observables for elastic Compton scattering from 3 He in Chiral Effective Field Theory with an explicit ∆(1232) degree of freedom (χEFT) for energies between 50 and 120 MeV. The γ 3 He amplitude is complete at N 3 LO, O(e 2 δ 3 ), and in general converges well order by order. It includes the dominant pion-loop and two-body currents, as well as the Delta excitation in the single-nucleon amplitude. Since the cross section is two to three times that for deuterium and the spin of polarised 3 He is predominantly carried by its constituent neutron, elastic Compton scattering promises information on both the scalar and spin polarisabilities of the neutron. We study in detail the sensitivities of 4 observables to the neutron polarisabilities: the cross section, the beam asymmetry and two double asymmetries resulting from circularly polarised photons and a longitudinally or transversely polarised target. Including the Delta enhances those asymmetries from which neutron spin polarisabilities could be extracted. We also correct previous, erroneous results at N 2 LO, i.e. without an explicit Delta, and compare to the same observables on proton, neutron and deuterium targets. An interactive Mathematica notebook of our results is available from hgrie@gwu.edu. 2S J=0 √ 2J + 1 P S J J M =−J

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“…In recent years there has been an upsurge in interest in the polarisabilities of the nucleon, both scalar and spin, with a number of new experiments planned, running or completed [13,14,15,16,17,18,19]. In addition the magnetic polarisability β p M1 has been shown to be a crucial input in the determination of the two-photon-exchange contribution to the Lamb shift in muonic hydrogen [20,21,22,23], and the isovector β p M1 − β n M1 has been connected to the nucleon electromagnetic mass difference [25,24,26,27,28].…”

Section: Introductionmentioning

confidence: 99%

Polarisabilities of the proton and neutron from Compton scattering

McGovern¹,

Grießhammer²,

Phillips³

2016

Proceedings of the 8th International Workshop on Chiral Dynamics — PoS(CD15)

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We have recently completed a high-precision extraction of the proton spin-independent polarisabilities from the world database of low-energy Compton scattering experiments, within the framework of chiral effective field theory (χEFT) with pions, nucleons, and the Delta(1232) as explicit degrees of freedom. Our Baldin-sum-rule-constrained results are, in units of 10 −4 fm 3 ,These were obtained in the heavy-baryon formulation, but almost identical results have been obtained in a covariant calculation. With the publication this year by Myers et al. of the results of the deuteron Compton scattering experiment using the Tagged-Photon Facility at the MAX IV Laboratory in Lund, Sweden, the world database has doubled in size, allowing the extraction of the isoscalar polarisabilities with unprecedented accuracy, and combined with the proton results we obtainA new generation of experiments with polarised beams have been performed at the Mainz Microtron, with the first results published this year by Martel et al. These experiments are sensitive to the spin polarisabilities, and we will discuss the predictions of χEFT for the relevant cross sections and asymmetries.

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Compton scattering from the deuteron below pion-production threshold

Cited by 22 publications

References 34 publications

Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities

Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities

Elastic Compton scattering from 3He and the role of the Delta

Polarisabilities of the proton and neutron from Compton scattering

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