Final-state interactions in two-nucleon knockout reactions

Colle, Camille; Cosyn, Wim; Ryckebusch, Jan

doi:10.1103/physrevc.93.034608

Cited by 22 publications

(59 citation statements)

References 33 publications

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“…The ratio of Eq. (20) can be connected to cross-section ratios accessible in p(A, p pN ) experiments and is for example not sensitive to FSI effects in the SRC pair. Fig.…”

Section: Resultsmentioning

confidence: 99%

Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

et al. 2018

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Short-range correlations (SRC) in asymmetric nuclei with an unusual neutronto-proton ratio can be studied with quasi-free two-nucleon knockout processes following the collision between accelerated ions and a proton target. We derive an approximate factorized cross section for those SRC-driven p(A, p N 1 N 2 ) reactions. Our reaction model hinges on the factorization properties of SRC-driven A(e, e N 1 N 2 ) reactions for which strong indications are found in theory-experiment comparisons. In order to put our model to the test we compare its predictions with results of 12 C(p, p pn) measurements conducted at Brookhaven National Laboratory (BNL) and find a fair agreement. The model can also reproduce characteristic features of SRC-driven two-nucleon knockout reactions, like back-to-back emission of the correlated nucleons. We study the asymmetry dependence of nuclear SRC by providing predictions for the ratio of proton-proton to proton-neutron knockout cross sections for the carbon isotopes 9−15 C thereby covering neutron excess values (N − Z)/Z between -0.5 and +0.5.

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“…The ratio of Eq. (20) can be connected to cross-section ratios accessible in p(A, p pN ) experiments and is for example not sensitive to FSI effects in the SRC pair. Fig.…”

Section: Resultsmentioning

confidence: 99%

Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

et al. 2018

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“…The LCA is a methodology with applications in nuclear reactions and nuclear structure. In LCA one can compute the observables for SRC dominated nucleon knockout reactions [10,[40][41][42][43]. Furthermore, the impact of SRC on nuclear momentum distributions [35,36] can be quantified across the nuclear mass range as even for the heaviest nuclei the numerical calculations are manageable.…”

Section: A Single-nucleon Momentum Distributionsmentioning

confidence: 99%

“…Attenuation will roughly equally affect protons and neutrons at the kinetic energies considered [51]. Singlecharge exchange (SCX), however, is an important correction factor [42] when extracting SRC information for two-nucleon knockout reactions. Indeed a considerable amount of detected pp knockout events originate from virtual-photon absorption on pn SRC pairs.…”

Section: B Tail Part Of Single-nucleon Momentum Distributionsmentioning

confidence: 99%

Isospin composition of the high-momentum fluctuations in nuclei from asymptotic momentum distributions

et al. 2019

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Background: High-momentum nucleons in a nuclear environment can be associated with short-range correlations (SRC) that primarily occur between nucleon pairs. Observations and theoretical developments have indicated that the SRC properties can be captured by general quantitative principles that are subject to model-dependence upon quantification. The variations in the aggregated effect of SRC across nuclei, however, can be quantified in an approximately model-independent fashion in terms of the so-called SRC scaling factors that capture the aggregated effect of SRC for a specific nucleus A relative to the deuteron (A-to-d).Purpose: Provide predictions for the SRC scaling factors across the nuclear periodic table and determine the relative contribution of the different nucleon pair combinations to this quantity. Determine the SRC scaling factors for both bound protons and bound neutrons and study how these quantities evolve with the neutron-to-proton ( N Z ) ratio in asymmetric nuclei. Methods: We employ the low-order correlation operator approximation (LCA) to compute the SRC contribution to the single-nucleon momentum distribution and ratios of A-to-d momentum distributions. We do this for a sample of fifteen nuclei from He to Pb thereby gaining access to the evolution of the SRC scaling factor with the nuclear mass 4 ≤ A ≤ 208 and the neutron-to-proton ratio 1.0 ≤ N Z ≤ 1.54. Results: We provide evidence for approximate A-to-d scaling of the single-nucleon momentum distribution at nucleon momenta exceeding about 4 fm −1 . For the studied sample of fifteen nuclei, the total SRC scaling factor is in the range 4.05-5.14 of which roughly 3 can be attributed to proton-neutron (pn) correlations. The SRC scaling factors receive sizeable contributions from pp and nn correlations. They depend on the N Z ratio reflecting the fact that the minority species (protons) becomes increasingly more short-range correlated with increasing N Z . We compare the computed SRC scaling factors in the LCA with those of ab-initio calculations and with measured quantities from SRC-sensitive inclusive electron-scattering data.Conclusions: It is shown that the LCA provides predictions for the SRC scaling factors across the nuclear table that are in line with measured values. In asymmetric nuclei there are sizeable differences between the SRC scaling factors for protons and neutrons. It is suggested that this phenomenon may impact the variations of the magnitude of the European muon collaboration (EMC) effect across nuclei. Our results corroborate the finding that SRC physics can be qualitatively understood by universal principles that build on local modifications of mean-field wave functions of nucleon pairs.

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“…These experiments have also revitalized interest in developing models to describe the inclusive 2p2h response function [20,21,22]. More evidence of two nucleon emission of correlated nucleon pairs has been thought to be found in the ArgoNeuT neutrino scattering experiment [23].…”

Section: Introductionmentioning

confidence: 99%

Two-nucleon emission in neutrino and electron scattering from nuclei: The modified convolution approximation

et al. 2018

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The theoretical formalism of inclusive lepton-nucleus scattering in the twonucleon emission channel is discussed in the context of a simplified approach, the modified convolution approximation. This allows one to write the 2p2h responses of the relativistic Fermi gas as a folding integral of two 1p1h responses with the energies and momenta transferred to each nucleon. The idea behind this method is to introduce different average momenta for the two initial nucleons in the matrix elements of the two-body current, with the innovation that they depend on the transferred energies and momenta. This method treats exactly the two-body phase space kinematics, and reduces the formulae of the response functions from seven-dimensional integrals over momenta to much simpler three-dimensional ones. The applicability of the method is checked by comparing with the full results within a model of electroweak meson-exchange currents. The predictions are accurate enough, especially in the low-energy threshold region where the average momentum approximation works the best.

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Final-state interactions in two-nucleon knockout reactions

Cited by 22 publications

References 33 publications

Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

Isospin composition of the high-momentum fluctuations in nuclei from asymptotic momentum distributions

Two-nucleon emission in neutrino and electron scattering from nuclei: The modified convolution approximation

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