DWIA in the momentum space for (?, ?0) reaction near threshold

Chumbalov, A.A.; Eramzhyan, R.A.; Kamalov, S.S.

doi:10.1007/bf01290662

Cited by 16 publications

(30 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[17]). The nuclear form factor was taken to be the vector form factor resulting from our ground state calculation, which corresponds to the charge form factor shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In order to compare to the non-relativistic, local approach used in the previous DWIA calculations, we performed a local calculation using the non-relativistic reduction of the direct ∆-graph as given in [25], which has also been used in [15,17]. The direct ∆-graph accounts for most of the total cross section (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…While many other works use a local approximation, in [12] the non-locality of the process is treated explicitly. Another group of models is mainly used for the threshold region and employs the distorted wave impulse approximation (DWIA) [14][15][16][17][18]. These studies take into account the non-resonant contributions, but resort for technical reasons to non-relativistic and local approximations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

1998

View full text Add to dashboard Cite

A relativistic and non-local model for the coherent photoproduction of pions on spin-zero nuclei is presented. The production operator is derived from an effective Lagrangian model that contains all the degrees of freedom known to contribute to the elementary process. Using the framework of DWIA, the matrix elements of this operator are evaluated using relativistic bound state wave functions. Final state interactions are accounted for via a pion-nucleus optical potential. The effects of in-medium modifications of the production operator are discussed. We give results for 12 C and 40 Ca, and compare our calculations to the data of the A2 collaboration at MAMI.

show abstract

“…[17]). The nuclear form factor was taken to be the vector form factor resulting from our ground state calculation, which corresponds to the charge form factor shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

1998

View full text Add to dashboard Cite

show abstract

“…This is in contrast to nonrelativistic treatments that, instead, use the vector density [1,2,[10][11][12]. The tensor density is a manifestation of the relativistic character of this approach.…”

mentioning

confidence: 85%

“…In this expressions represents the effective (or optimal) value of the Mandelstam variable s at which the elementary amplitude should be evaluated [10] and Q ≡ |k c.m. − q c.m.…”

mentioning

confidence: 99%

Nuclear dependence of the coherentηphotoproduction reaction in a relativistic approach

et al. 1998

View full text Add to dashboard Cite

We study the nuclear (or A) dependence of the coherent η photoproduction reaction in a relativistic impulse approximation approach. We use a standard relativistic parameterization of the elementary amplitude, based on a set of four Lorentz-and gauge-invariant amplitudes, to calculate the coherent production cross section from 4 He, 12 C, and 40 Ca. In contrast to nonrelativistic treatments, our approach maintains the full relativistic structure of the process. The nuclear structure affects the process through the ground-state tensor density. This density is sensitive to relativistic effects and depends on A in a different manner than the vector density used in nonrelativistic approaches. This peculiar dependence results in 4 He having a cross section significantly smaller than that of 12 Cin contrast to existent nonrelativistic calculations. Distortion effects are incorporated through an η-nucleus optical potential that is computed in a simple "tρ" approximation. The nuclear dependence of the coherent η photoproduction process offers a unique opportunity to investigate medium modifications to the elementary γN → ηN amplitude and might help distinguish between different theoretical models that provide an equally good description of the elementary process. In particular, the role played by the background is very significant in spin-isospin saturated nuclei where the dominant resonance S 11 (1535) is suppressed. Furthermore, this reaction contributes significantly to our understanding of nucleon-resonance formation and sheds some light on the propagation of these resonances through the nuclear medium. The A dependence of this reaction is affected by the propagation of the produced η-meson through its interaction with the nucleus. Moreover, the coherent process is sensitive to the whole nuclear volume and, thus, depends on bulk properties of the nucleus. While nonrelativistic treatments suggest that nuclear-structure effects manifest themselves through the conserved vector (or baryon) density [1-3], our recent relativistic analysis suggests that, rather, it is the tensor density that affects the process [4]. This represents an important result, since the tensor density-a quantity as fundamental as the vector density-is not well determined by experiment.An early nonrelativistic study by Bennhold and Tanabe of the coherent η photoproduction process predicted 4 He to have the largest cross section of the three nuclei 4 He, 12 C, and 40 Ca [1]. A recent nonrelativistic study of this process seems to confirm this earlier prediction, although important quantitative differences do emerge [3]. In nonrelativistic treatments the coherent cross section is proportional to the square of the Fourier transform of the vector density. Thus, the particular A dependence predicted by these calculations emerges from a competition between A, which tends to increase the cross section for larger nuclei, and the vector form-factor-which falls rapidly with A. This competition results in 4 He having the largest cross section. Theoretical stud...

show abstract

Coherent photoproduction of η-mesons off 3He – search for η-mesic nuclei

et al. 2012

View full text Add to dashboard Cite

Coherent photoproduction of η-mesons off 3 He, i.e. the reaction γ 3 He → η 3 He, has been investigated in the near-threshold region. The experiment was performed at the Glasgow tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball -TAPS detector. Angular distributions and the total cross section were measured using the η → γγ and η → 3π 0 → 6γ decay channels. The observed extremely sharp rise of the cross section at threshold and the behavior of the angular distributions are evidence for a strong η 3 He final state interaction, pointing to the existence of a resonant state. The search for further evidence of this state in the excitation function of π 0 -proton back-to-back emission in the γ 3 He → π 0 pX reaction revealed a very complicated structure of the background and could not support previous conclusions.

show abstract

DWIA in the momentum space for (?, ?0) reaction near threshold

Cited by 16 publications

References 20 publications

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

Nuclear dependence of the coherentηphotoproduction reaction in a relativistic approach

Coherent photoproduction of η-mesons off 3He – search for η-mesic nuclei

Contact Info

Product

Resources

About