Anl-independent representation of a Majorana potential

2011

Phys. Rev. C

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For6 Li scattering from 12 C at five laboratory energies from 90 to 318 MeV, we study the dynamic polarization potential, DPP, due to the breakup of the projectile. The breakup is evaluated using standard continuum discretized coupled-channels formalism applied to a two-body cluster model of the projectile. The DPP is evaluated over a wide radial range using both direct S-matrix-to-potential inversion and trivially equivalent local potential methods which yield substantially and systematically different results. The radius at which the real DPP changes from external repulsion to interior attraction varies systematically with energy. This should be experimentally testable because, according to notch tests, this crossover radius is within a radial range to which elastic scattering should be sensitive. The imaginary DPP has an emissive (generative) region at the lower energies; this may be associated with counterintuitive properties of |S L |.

Section: B Comparing S-matrix and Telp Dppsmentioning

confidence: 99%

Dynamic polarization potential due to6Li breakup on12C

Pang

2011

Phys. Rev. C

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“…(8), some degree of waviness in the l-independent central potential, and probably the tensor interaction, that we extract. The oscillatory features that are evident on the small components of the potential can be understood in terms of the previously mentioned fact that strongly l-dependent potentials, whether parity dependent or having other forms of l dependence, can be represented by l-independent potentials having oscillatory or other nonregular shapes [18,19]. In Fig.…”

Section: A Inversion Of the S Matrix S J Ll For D + 40 Camentioning

confidence: 81%

“…In particular, we know that the inversion of an S matrix generated by an l-dependent local potential yields, in general, a potential with oscillatory features [18,19]. Hence, wavy potentials, as found for the J -weighted case, may reflect genuine dynamics corresponding to an underlying l-dependent DPP.…”

Section: A Inversion Of the S Matrix S J Ll For D + 40 Camentioning

confidence: 91%

Pickup coupling effects in deuteron scattering: The case ofd+Ca40

Keeley

2008

Phys. Rev. C

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The dynamic polarization potential (DPP) contribution to the effective deuteron-nucleus interaction is evaluated by means of coupled reaction channel (CRC) calculations followed by S-matrix-to-potential inversion. The full coupled channel S matrix S J l l is inverted using the iterative-perturbative algorithm to yield a potential that includes a complex T R tensor term as well as central and spin-orbit components. The differences between the various components of the inverted potential and the corresponding terms in the bare potential of the CRC calculation constitute a local equivalent representation of the complete DPP that is generated by the reaction channel coupling. The magnitude of the DPP, the real part in particular, is much less than that found in earlier calculations in which the nonorthogonality terms were omitted. The characteristic features of the tensor part of the DPP were traced to breakup and reorientation processes in the entrance deuteron channel that had been included with the pickup. The contribution of stripping to the deuteron-nucleus interaction is also discussed.

“…A problem occurs in establishing parity dependence: S l that originates from the parity-dependent potential can always be fitted, by S l → V (r) inversion [6], with an l-independent potential. In the α plus 20 Ne case the l-independent potential was found [70], in spite of the smallness of the Majorana term, to be markedly undulatory and would not have been discovered by standard fitting of the elastic scattering angular distributions.…”

Section: G the Contribution Of Knock-on Exchangementioning

confidence: 88%

The angular momentum dependence of nuclear optical potentials

2019

Eur. Phys. J. A

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The nuclear optical model potential (OMP) is generally assumed to be independent of the orbital angular momentum, l, of the interacting nuclei. Nucleon-nucleus and nucleus-nucleus interactions are customarily l independent in calculations of nuclear elastic scattering and in standard reaction codes. The evidence for various forms of l dependence of OMPs is reviewed and the importance of implementing these forms is evaluated. Existing arguments and evidence for l dependence are reviewed and new arguments and calculations are introduced. The relationship is examined between (i) l dependence, and, (ii) the undularity (waviness) of l-independent potentials that are S-matrix equivalent to l-dependent potentials. Such undularity is a property of the dynamic polarisation potential (DPP) generated by the coupling to reaction channels, or by coupling to excited states of the target or projectile nuclei. Various examples, particularly involving weakly bound projectile nuclei, are presented. Such undularity also occurs in l-independent potentials that have been found in model independent fits to precise wide angular range elastic scattering angular distributions.Cases of such phenomenological undularity, for both light and heavy ions, are referenced and shown to be related to undulatory properties of the dynamic polarisation potentials (DPPs) arising from channel coupling. Other forms of l dependence, that could be standard options in direct reaction codes, are noted. Of particular importance are l dependencies arising from full antisymmetrization.The case is made that reaction-induced l dependence is a general property of nucleon-nucleus and nucleus-nucleus interactions and represents a valid extension of the nuclear optical model.