Measurement of Isospin Mixing in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>and Its Implications for Charge-Symmetry Breaking

Blilie, C. L.; Dehnhard, D.; Holtkamp, D. B.; Cottingame, W. B.; Halderson, Dean; Morris, C. L.; Moore, C. F.; Seidl, P.A.; Ohnuma, H.; Maeda, K.

doi:10.1103/physrevlett.57.543

Cited by 21 publications

(17 citation statements)

References 21 publications

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“…A similar procedure was followed in Ref. [8], where RCCSM predictions for the pion inelastic scattering yields were successful in reproducing excitation energy spectra.…”

Section: Introductionmentioning

confidence: 95%

“…Such a large deviation from unity would have fundamental implications for the hadronic interaction, since it implies the existence of a charge symmetry-breaking (CSB) component of the internucleon force which, under standard assumptions, cannot be accounted for with the Coulomb interaction alone [1 -3]. However, work involving separate measurements of the cr(p, p), o(p, p), and tr(p, n) reactions, as well as 4He(e, e'N) and pion inelastic scattering studies call these results seriously into question [4][5][6][7][8] Pion inelastic scattering data have provided valuable information on the isospin character of the 4He continuum and have also provided tests of microscopic approaches to the four-body nuclear structure problem [8].…”

Section: Introductionmentioning

confidence: 99%

“…We note the at, tractive feature that, in this model, resonant excitations of' He and quasifree particle knockout are incorporated within the same theoretical framework. Lowenergy cross sections, polarizations, and analyzing powers for the H(p, n) He reaction, H(p, p) angular dist, ributions, and inclusive n+ and 7r scattering spectra [8] have been successfully described by the RCCSM [2,19,20].…”

Section: Introductionmentioning

confidence: 99%

“…[2,8,19,20], the ground state of 4He is assumed to be of purely (Os) form. The basis for the excited 0+ state consists of higher s orbitals up to n = 8.…”

Section: Introductionmentioning

confidence: 99%

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Inelastic scattering of polarized protons fromHe4at 500 and 800 MeV

et al. 1992

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Inclusive He(p, p') spectra were measured at incident energies T"=500 and 800 MeV over a range of forward scattering angles between 5' and 30'. The first excited 0+, T=O state at 20.1 MeV and the 2, T=O state at 22. 1 MeV appear as distinct structures in the spectra. Angular distributions of diR'erential cross sections o' and analyzing powers A"were extracted for these states and for regions of excitation in the continuum up to 40 MeV. Distorted-wave calculations for inelastic scattering using transition densities from the recoil corrected continuum shell model (RCCSM) were compared with the data. The RCCSM generally predicts too small cr and too large A". Assuming a pure giant monopole excitation for the 20.1-MeV, 0 state, we found greater giant monopole resonance strength than has been deduced from He(e, e') studies. PACS number(s): 25.40. Ep, 24.70.+s

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“…A similar procedure was followed in Ref. [8], where RCCSM predictions for the pion inelastic scattering yields were successful in reproducing excitation energy spectra.…”

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[2,8,19,20], the ground state of 4He is assumed to be of purely (Os) form. The basis for the excited 0+ state consists of higher s orbitals up to n = 8.…”

Section: Introductionmentioning

confidence: 99%

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Inelastic scattering of polarized protons fromHe4at 500 and 800 MeV

et al. 1992

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“…-state telescopes at 60', 90'" and 120' to obtain simultaneous yields for the He(e, e' He)"and He(e, e' H)p reactions. In the only experiment to use real photons, Phillips et al [13] [14] as well as (p, p' H)/(p, p' He) reactions [15] both indicated no violation of charge symmetry, although the tr /tt ratio may be insensitive to isospin mixing due to nuclear structure eA'ects [16]. The inconsistency between the simultaneous ratio measurements …”

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confidence: 99%

Simultaneous measurement of the (γ,p)/(γ,n) cross-section ratio inHe4as a test of charge symmetry

et al. 1994

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We have measured (y, p) and (y, n) differential yields at 90' for the two-body photodisintegration of He using tagged photons of energy E"=25-60 MeV. Data for both channels were obtained simultaneously using windowless hE-E telescopes to detect the He and H recoils. The ratio of our angleintegrated yields, which is insensitive to systematic uncertainties due to the simultaneity of the measurements, agrees with calculations employing only charge-symmetric nuclear interactions. Thus, within the present errors, our data show no evidence of a significant charge-symmetry violation in He in this energy range. PACS numbers: 25.20.Dc, 25. 10.+s, 27. ]0.+h The question of charge symmetry in He has been a long-standing problem in nuclear physics. If charge symmetry is strictly valid, then the ratio of the two-body photodisintegration cross sections, R"=a(y-,p)/o(y, n), is expected to be unity (for pure E I radiation). EA'ects such as Coulomb interactions or non-E 1 multipoles can slightly modify this value, increasing the ratio to R~-1.1 in the photon energy range E"=25-35 MeV. The problem was summarized in 1983 by Calarco, Berman, and Donnelly [I] in a comprehensive review of all photonuclear (and capture) data up to that time, leading to the surprising conclusion that R"=1. 7-1.2 for E, =25-35 MeV, dilfering substantially from the simple charge-symmetry prediction. Theoretical attempts which include charge-symmetric nuclear interactions in a shell model [2,3] and a resonating group model [4,5] have failed to reproduce this large value of the ratio. It should be noted, however, that the recommended cross sections comprising the ratio in Ref. [I] were determined from in ditidual measurements of the (y,p) and (y, n) channels separately. Since this review, three new measurements of the proton channel have been reported [6-8]. The data from [6,7] are more consistent with the recommended photoneutron cross section, while [8] reports a cross section nearly twice as large, in agreement with the recommended proton cross section. The only new published neutron data are from a capture reaction [9] which finds a peak cross-section value that is consistent with the recommended neutron value.In addition to these new measurements of the individual two-body channels, a recent elastic photon scattering experiment [10] inferred the total photoabsorption cross section in a model-independent manner through the optical theorem and a dispersion relation. While their result can say nothing about the relative contributions of the (y,p) and (y, n) channels (and hence, the ratio), it does impose a significant constraint on the sum of the two cross sections. This new photon scattering result (a) agrees with the sum of the recommended cross sections in Ref. [I] (which give the large value of R"), (b) disagrees with the sum of the recent photoproton data [6,7] and the recommended photoneutron values (where R" is closer to unity), (c) agrees with the sum of Ref. [8] and the recommended neutron cross section, and (d) agrees with the sum of the latest...

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