Determination of the strong interaction shift in pionic hydrogen with a high resolution crystal spectrometer system

Beer, W.; Bogdan, M.; Goudsmit, P.F.A.; Leisi, H.J.; Hassani, A.; Sigg, D.; Thomann, St.; Volken, W.; Bovet, D.; Bovet, E.; Chatellard, D.; Egger, J. P.; Fiorucci, G.; Gabathuler, K.; Simons, L. M.

doi:10.1016/0370-2693(91)91317-o

Cited by 38 publications

(4 citation statements)

References 9 publications

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“…Of course, the pure isospin scattering lengths would then be outside the range from partial wave analyses. This contradiction between the amplitude analysis and pionic hydrogen result discussed, e. g. , by Koch [34] seems now to be resolved by the new value of the s-wave energy shift obtained by the same group [35], which yields co+ --(0.086+0.004) p in agreement with the Karlsruhe prediction. Combined with the Panofsky ratio result above, this would give now the negligible 3ao++ --( -0.005+ 0.011)p i.…”

Section: A Direct Absorptionmentioning

confidence: 78%

Impact ofpp→ppπ0data to negative-pion absorption on proton pairs

Niskanen

1994

Phys. Rev. C

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Recent data on the reaction pp~ppvr close to threshold indicate unexpectedly large s-wave pion production, with a possible explanation from a heavy meson exchange contribution to the axial charge. An amplitude with the same quantum numbers appears also in negative-pion absorption on proton pairs in light nuclei. In this paper the efFect of this enhancement is estimated and found to be significant in the observables of absorption on He. Also some predictions are given for the qualitative efFect in pn M (pp)s PACS number(s): 25.80. Hp, 13.75.Cs, 13.75.Gx

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Section: A Direct Absorptionmentioning

confidence: 78%

Impact ofpp→ppπ0data to negative-pion absorption on proton pairs

Niskanen

1994

Phys. Rev. C

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“…On the other hand, there exists experimental information that is more directly related to the scattering lengths. For instance, from the branching ratios of the decay of pionic hydrogen [16], one obtains a 1/2 − a 3/2 = 0.263 ± 0.005m −1 π ; from the measured 1s width of pionic hydrogen [17], one obtains 2a 1/2 + a 3/2 = 0.258 ± 0.012m −1 π . Combining the two results yields…”

Section: B Pion Rescatteringmentioning

confidence: 99%

Role of heavy-meson exchange in pion production near threshold

1994

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Recent calculations of s-wave pion production have severely underestimated the accurately known pp → ppπ 0 total cross section near threshold. In these calculations, only the single-nucleon axial-charge operator is considered. We have calculated, in addition to the one-body term, the two-body contributions to this reaction that arise from the exchange of mesons. We find that the inclusion of the scalar σ-meson exchange current (and lesser contributions from other mesons) increases the cross section by about a factor of five, and leads to excellent agreement with the data. The results are neither very sensitive to changes in the distorting potential that generates the N N wave function, nor to different choices for the meson-nucleon form factors. We argue that pp → ppπ 0 data provide direct experimental evidence for meson- * Electonic communication to charlie@venus.iucf.indiana.edu 1 exchange contributions to the axial current.

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“…(1) Recent measurements of pion-nucleon elastic [2] and charge-exchange [3] scattering for T p # 50 MeV have yielded data of exceptionally high quality. A new pionic atom measurement has also been recently obtained [4]. 2There is a minimum in each of the amplitudes in this energy range.…”

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confidence: 99%

Isospin Breaking in Low-Energy Pion-Nucleon Scattering

1995

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We have analyzed low-energy pion-nucleon data for isospin invariance by comparing chargeexchange amplitudes derived from charge-exchange data with those predicted from recent~p elastic data through the application of isospin invariance. A discrepancy of the order of 7% is observed beyond the contributions of the~p Coulomb interaction and the hadronic mass differences. PACS numbers: 13.75.Gx, 24.80.Dc, 25.80.Gn fcEx = Of the eight reactions of the form~N~' N' the only three directly accessible experimentally are those with charged pion beams and proton targets: 7Tp elasticscattering, with amplitudes f, and 7r p~~" n chargeexchange (CEX) scattering, with amplitude fcEx. Isospin conservation gives a relationship among these three amplitudes, the triangle identity

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Determination of the strong interaction shift in pionic hydrogen with a high resolution crystal spectrometer system

Cited by 38 publications

References 9 publications

Impact ofpp→ppπ0data to negative-pion absorption on proton pairs

Impact ofpp→ppπ0data to negative-pion absorption on proton pairs

Role of heavy-meson exchange in pion production near threshold

Isospin Breaking in Low-Energy Pion-Nucleon Scattering

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