Analyzing power in nd elastic scattering at Enlab=3 MeV. Measurement and calculation

McAninch, J.E.; Haeberli, W.; Witała, H.; Glöckle, W.; Golak, J.

doi:10.1016/0370-2693(93)90185-k

Cited by 29 publications

(16 citation statements)

References 23 publications

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“…In this way the TM' and Urbana IX 3NF's seem to solve partially the A y problem found at higher energies in [27,53]. At 3 MeV the clear discrepancy of all theoretical predictions to the nd data of [54] is seen. At such a low energy it is well known that Coulomb force effects are large for A y decreasing significantly its maximum when compared to nd data [55].…”

Section: Predictions Of 3nf Effects and Comparison To Datamentioning

confidence: 71%

“…Also the isospin and coordinate transformation matrix elements are standard and we refer to [48]. [61] (pd-crosses) and [54] (nd-circles), at 65 MeV from [61] (pd-crosses) and [62] (nd-circles), at 135 MeV from [27] (pd-circles 150 MeV), [64] (pd-crosses 146 MeV), [65] (pd-x's 155 MeV), and at 190 MeV from [27] (pd-crosses 190 MeV), [66] (pd-circles 198 MeV), [67] (pd-squares 197 MeV). Fig.…”

Section: Discussionmentioning

confidence: 99%

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Ndelastic scattering as a tool to probe properties of3Nforces

et al. 2001

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Faddeev equations for elastic Nd scattering have been solved using modern NN forces combined with the Tucson-Melbourne two-pion exchange threenucleon force, with a modification thereof closer to chiral symmetry and the Urbana IX three-nucleon force. Theoretical predictions for the differential cross section and several spin observables using NN forces only and NN forces combined with three-nucleon force models are compared to each other and to the existing data. A wide range of energies from 3 to 200 MeV is covered. Especially at the higher energies striking three-nucleon force effects are found, some of which are supported by the still rare set of data, some are in conflict with data and thus very likely point to defects in those three-nucleon force models.

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Section: Predictions Of 3nf Effects and Comparison To Datamentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Ndelastic scattering as a tool to probe properties of3Nforces

et al. 2001

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“…We note that the AV18 prediction for the nd A y at E lab = 3 MeV [23] underestimates the data near the maximum by about 30%. Also, from Tables I and II we learn that the effect of a change in the tensor force is larger in the 2-body system than in the 3-body system.…”

Section: Changing the Nn Potentialmentioning

confidence: 99%

TheAypuzzle and the nuclear force

Hüber

Friar

1998

Phys. Rev. C

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The nucleon-deuteron analyzing power A y in elastic nucleon-deuteron scattering poses a longstanding puzzle. At energies E lab below approximately 30MeV A y cannot be described by any realistic NN force. The inclusion of existing three-nucleon forces does not improve the situation. Because of recent questions about the 3 P J NN phases, we examine whether reasonable changes in the NN force can resolve the puzzle. In order to do this we investigate the effect on the 3 P J waves produced by changes in different parts of the potential (viz., the central force, tensor force, etc.), as well as on the 2-body observables and on A y . We find that it is not possible with reasonable changes in the NN potential to increase the 3-body A y and at the same time to keep the 2-body observables unchanged. We therefore conclude that the A y puzzle is likely to be solved by new three-nucleon forces, such as those of spin-orbit type, whichhave not yet been taken into account.PACS numbers:

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“…The dotted curve represents the result from the 'Modified' chiral potential (see text) and the dash-dot line is predicted by the NLO chiral potential by Epelbaum et al [30]. Data at 3 MeV are from [44] (nd, squares), at 10 MeV from [46] (nd, squares), and at 65 MeV from [48] (nd, squares) and [49] (pd, crosses). Fig.…”

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confidence: 99%

ChiralNNmodel andAypuzzle

2002

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We analyze the results by chiral N N models for the two-nucleon system and calculate the predictions for the nucleon vector analyzing power of elastic nucleon-deuteron (N d) scattering, A y , by these models. Our conclusion is that a quantitative chiral two-nucleon potential does not resolve the N d A y puzzle (when only two-body forces are included).PACS numbers: 21.30.+y, 21.45.+v, 25.10.+s, 27.10+h The term A y puzzle refers to the inability to explain the nucleon vector analyzing power A y in elastic nucleon-deuteron (Nd) scattering below 30 MeV laboratory energy for the incident nucleon by means of three-body calculations in which only two-nucleon forces are applied. The problem showed up as soon as it was possible to conduct three-body continuum calculations with realistic NN potentials. The first such calculation was performed by Stolk and Tjon [1] in 1978 using the Reid soft-core potential [2], and the first calculations with (a separable representation of) the Paris potential [3] were conducted by the Graz-Osaka group in 1987 [4]; in both cases, the A y predictions showed the characteristic problem. Finally, the 'puzzle' became proverbial when rigorous three-nucleon continuum Faddeev calculations using realistic forces were started on a large scale [5]. Over the years, many measurements and calculations of Nd A y were performed (including the pd reaction that involves the Coulomb force [6]) which all confirmed that the problem was real (see Ref.[7] for a review): For energies below 20 MeV, the A y is predicted about 30% too small in the angular region around 120 deg center-of-mass angle where the maximum occurs.There have been many attempts to solve the problem. Already in the very early stages of three-body continuum calculations, when only schematic NN potentials were applied, it was noticed that the Nd A y predictions depend very sensitively on the strength of the input NN potential in the triplet P waves [8,9]-a sensitivity that was confirmed in later calculations using realistic forces [10]. Based upon this experience, Wita la and Glöckle [11] showed in 1991 that small changes in those 3 P wave potentials could remove the discrepancy. This finding gave rise to systematic investigations of the question whether the small variations of the low-energy phase shifts of, particularly, those triplet P waves necessary to explain the Nd A y are consistent with the NN data base. While Tornow and coworkers [12] suggest that the low-energy NN data may leave some lattitude in the NN 3 P waves that could * On leave from University of Salamanca, Spain. Another important observation has been that conventional three-nucleon forces (when added to a realistic two-nucleon potential) change the predictions for Nd A y only slightly and do not improve them [14,6]. Therefore, the general perception in the community has shifted towards the believe that the A y puzzle is the 'smoking gun' for new types of three-nucleon forces [15][16][17][18] or new physics [19].However, very recently, there has been an apparent indicatio...

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Analyzing power in nd elastic scattering at Enlab=3 MeV. Measurement and calculation

Cited by 29 publications

References 23 publications

Ndelastic scattering as a tool to probe properties of3Nforces

Ndelastic scattering as a tool to probe properties of3Nforces

TheAypuzzle and the nuclear force

ChiralNNmodel andAypuzzle

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