Recent advances in the description of electromagnetic two-nucleon knockout reactions are reviewed. The sensitivity to different types of correlations and to their treatment in the nuclear wave functions, the effects of final-state interactions and the role of center-of-mass effects in connection with the problem of the lack of orthogonality between initial bound states and final scattering states obtained by the use of an energy-dependent optical-model potential are discussed. Results are presented for proton-proton and proton-neutron knockout off 16O also in comparison with the available data.
We study neutrino-induced nucleon knockout off atomic nuclei and examine the polarization properties of the ejectile. A detailed study of the spin dependence of the outgoing nucleon is presented. The numerical results are derived within a non-relativistic plane-wave impulse-approximation approach. Our calculations reveal large polarization asymmetries, and clear dissimilarities between neutrino- and antineutrino-induced reactions. They reflect the fact that neutrino-induced nucleon knockout is dominated by the transverse axial current and gains its major contributions from forward nucleon emis…
The influence of the mutual interaction between the two outgoing nucleons (NN-FSI) in electro- and photoinduced two-nucleon knockout from $^{16}O$ has been investigated perturbatively. It turns out that the effect of NN-FSI depends on the kinematics and on the type of reaction considered. In the kinematics studied so far, the effect is larger in pp- than in pn-knockout and in electron induced than in photoinduced reactions.
The attempts to investigate correlations in electromagnetically induced one- and two-nucleon knockout are reviewed. The theoretical framework for cross section calculations is outlined and some results are presented for the exclusive $^{16}$O($e,e'p)^{15}$N and $^{16}$O($e,e'pp)^{14}$C reactions. For the ($e,e'p$) reaction attention is focussed on extracting the spectroscopic factors. For the ($e,e'pp$) reaction the possibility of obtaining direct and clear information on short-range correlations is discussed.
The contributions from $^{12}$C$(e,e'pn)$ and $^{12}$C$(e,e'pp)$ to the semi-exclusive $^{12}$C$(e,e'p)$ cross section have been calculated in an unfactorized model for two-nucleon emission. We assume direct two-nucleon knockout after virtual photon coupling with the two-body pion-exchange currents in the target nucleus. Results are presented at several kinematical conditions in the dip and $Δ$(1232) regions. The calculated two-nucleon knockout strength is observed to account for a large fraction of the measured $(e,e'p)$ strength above the two-nucleon emission threshold.
Understanding of inclusive one-nucleon knockout reactions for long-lived fission fragments (LLFPs) is crucial for nuclear transmutation studies. However, the particle and heavy ion transport code system (PHITS) severely overshoots the inclusive one-nucleon knockout cross sections sigma_-1N. Therefore development of a reaction model for describing the inclusive one-nucleon knockout processes is necessary. A key is specification of the position and the momentum of a nucleon inside a nucleus to be struck by the incident nucleon. In this paper the semiclassical distorted wave model incorporating t…
The contributions of short-range nucleon-nucleon correlations, meson exchange current (MEC) corrections and the influence of Delta isobar excitations (isobaric currents, IC) on photon induced two-nucleon knockout reactions are investigated. The nuclear structure functions are evaluated for the system of infinite nuclear matter. This allows a systematic investigation of the relative importance of the various contributions (MEC, IC and correlations) in different kinematical regions. Nucleon-nucleon (NN) correlations derived from a realistic NN interaction by solving the Bethe-Goldstone equation …
Cross sections and photon asymmetries of the exclusive 16O(γ,pn)14N and 16O(γ,pp)14C knockout reactions are calculated for transitions to the low-lying discrete final states of the residual nucleus in the photon-energy range between 100 and 400 MeV. Exclusive reactions may represent a test of reaction mechanisms and a promising tool for investigating the dynamics of nucleon pairs in different states. Cross sections and asymmetries for both (γ,pn) and (γ,pp) turn out to be only slightly affected by short-range correlations and dominated by two-body currents. Therefore, two-nucleon knockout reac…
The cross sections of the ($e,e'N$) and ($γ,p$) reactions on $^{16}$O are calculated, for the transitions to the $1/2^{-}$ ground state and the first $3/2^{-}$ excited state of the residual nucleus, using single-particle overlap functions obtained on the basis of one-body density matrices within different correlation methods. The electron-induced one-nucleon knockout reaction is treated within a nonrelativistic DWIA framework. The theoretical treatment of the ($γ,p$) reaction includes both contributions of the direct knockout mechanism and of meson-exchange currents. The results are sensitive …
Electro-production of pions and kaons at the kinematics of quasi-elastic knockout (which is well known in the physics of atomic nucleus and corresponds to the $t$-pole diagram) is proposed for obtaining their momentum distribution (MD) in various channels of virtual decay $N \to B+π$, $B=N$, $Δ$, $N^*$, $N^{**}$, and $N \to Y+K$, $Y=Λ$, $Σ$. It is a powerful tool for investigation of a quark microscopic picture of the meson cloud in the nucleon. A model of scalar $q \bar{q}$ ($^3P_0$) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions (MD) in th…
Polarization observables for the A(e,e'NN) and A(γ,NN) reactions are a powerful tool to study nucleon-nucleon correlations in the nuclear medium. In this paper, model calculations for the ^{4}He(e,e'pp), ^{16}O(\vec{e},e'\vec{p}p), ^{16}O(\vec{e},e' \vec{p}n) and ^{12}C(\vecγ,\vec{p}N) reactions are presented. The sensitivity of the differential cross sections and polarization observables to central and spin-dependent nucleon-nucleon correlations is discussed.
The influence of the mutual interaction between the two outgoing nucleons (NN-FSI) in electro- and photoinduced two-nucleon knockout from $^{16}O$ has been investigated perturbatively. It turns out that the effect of NN-FSI depends on the kinematics and on the type of reaction considered. The effect is generally larger in pp- than in pn-knockout and in electron induced than in photoinduced reactions. In superparallel kinematics NN-FSI leads in the $(e,e'pp)$ channel to a strong increase of the cross section, that is mainly due to a strong enhancement of the $Δ$-current contribution. In pn-emis…
Differential (e,e'pp) measurements are presently recognized as a way of studying short-range correlations in finite nuclei. The ($\vec{e},e'\vec{p}p$) and ($\vec{e},e'\vec{p}n$) differential cross section and polarization observables are studied in a microscopic model that accounts for the short-range correlations, outgoing-nucleon distortions, meson-exchange and $Δ$-isobar currents. It is pointed out that polarization observables represent an attractive alternative for absolute electronuclear two-nucleon knockout measurements. In the polarization transfer $P'_t$ for ($\vec{e},e'\vec{p}p$), th…
Developed earlier concept of quasielastic knock out of pions from nucleons by high-energy electrons is propounded as a tool for checking microscopical model ($^3P_0$ - fluctuation) for decay of N to different channels $π+B$ and Preparata model of nucleus structure.
The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The ($γ,pp$) and ($γ,pn$) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei $^{16}$O and $^{12}$C and photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on $^3S_1(T=0)$ proton-neutron and $^1S_0(T=1)$ proton-proton pairs …
Reactions that involve the direct and sudden removal of a pair of like or unlike nucleons from a fast projectile beam by a light target nucleus are considered. Specifically, we study the three two-nucleon removal channels from $^{12}${C} that populate final states in the $^{10}${Be}, $^{10}${B} and $^{10}${C} reaction residues. The calculated two-nucleon removal cross sections and the residue momentum distributions are compared with available high energy data at 250, 1050 and 2010 MeV per nucleon, data that are inclusive with respect to the bound final-states of the residues. The measured $np$…
We develop a fully relativistic distorted wave impulse approximation model for electron- and photon-induced one proton knockout reactions. The relativistic mean field for the bound state and the Pauli reduction for the scattering state are used, including a fully relativistic electromagnetic current operator. Results for 16O(e,e'p) cross section and structure functions are shown in various kinematic conditions and compared with nonrelativistic calculations. Nuclear transparency calculations in a Q^2 range between 0.3 and 1.8 (GeV/c)^2 are presented. Results for 16O(gamma,p) differential cross …
The contribution of the $Δ$(1232) isobar to the electromagnetic current of the two-nucleon system and its role in ($γ$,NN) processes is investigated. The difference between the genuine $Δ$-excitation current and that part of the current connected to the deexcitation of a preformed $Δ$ in the target nucleus is stressed. The latter cannot lead to a resonant behaviour of matrix elements for energies in the $Δ$ region. The reaction $^{16}O(γ,pp)^{14}C$, where the $Δ$ contribution is dominant at intermediate energies, is considered. The large variations found in the cross sections for different tre…
We present a model to calculate cross sections for electroinduced two-nucleon emission from finite nuclei. Short-range correlations in the wave functions and meson-exchange contributions to the photoabsorption process are implemented. Effects of the short-range correlations are studied with the aid of a perturbation expansion method with various choices of the Jastrow correlation function. The model is used to investigate the relative importance of the different reaction mechanisms contributing to the A(e,e$'$pn) and A(e,e$'$pp) process. Representative examples for the target nuclei $^{12}$C a…
We address the issue whether quasifree single-nucleon knockout measurements carry sufficient information about the nuclear interior. To this end, we present comparisons of the reaction probability densities for $A(e,e'p)$ and $A(p,2p)$ in quasifree kinematics for the target nuclei $^{4}$He, $^{12}$C, $^{56}$Fe, and $^{208}$Pb. We adopt a comprehensive framework based on the impulse approximation and on a relativized extension of Glauber multiple-scattering reaction theory in which the medium effects related to short-range correlations (SRC) are implemented. It is demonstrated that SRC weaken t…
The nuclear structure dependence of direct reactions that remove a pair of like or unlike nucleons from a fast $^{12}$C projectile beam are considered. Specifically, we study the differences in the two-nucleon correlations present and the predicted removal cross sections when using $p$-shell shell-model and multi-$\hbarω$ no-core shell-model (NCSM) descriptions of the two-nucleon overlaps for the transitions to the mass $A$=10 projectile residues. The NCSM calculations use modern chiral two-nucleon and three-nucleon (NN+3N) interactions. The $np$-removal cross sections to low-lying $T$=0, $^{1…
We study medium modifications of the nucleon-nucleon (NN) cross sections and their influence on the nucleon knockout reactions. Using the eikonal approximation, we compare the results obtained with free NN cross sections with those obtained with a purely geometrical treatment of Pauli-blocking and with NN obtained with more elaborated Dirac-Bruecker methods. The medium effects are parametrized in terms of the baryon density. We focus on symmetric nuclear matter, although the geometrical Pauli-blocking allows for the treatment of asymmetric nuclear matter. It is shown that medium effects can ch…
The role of center-of mass (CM) effects in the one-body nuclear current in the description of electromagnetically induced two-nucleon knockout reactions is discussed in connection with the problem of the lack of orthogonality between initial bound states and final scattering states obtained by the use of an energy-dependent optical model potential. Results for the cross sections of the exclusive $^{16}$O(e,e$'$pp)$^{14}$C and $^{16}$O($γ$,pp)$^{14}$C knockout reactions in different kinematics are presented and discussed. In super-parallel kinematics CM effects produce a strong enhancement of t…
The nonlinear model of pionic condensate in nuclei by G. Preparata can be efficiently verified by investigation of the quasielastic knockout process of pions out of nuclei by high energy electrons. First, a momentum distribution (MD) of the collective pions has a bright maximum at q=0.3 Gev.Second the excitation spectrum of a recoil nucleus is concentrated at low energies E lesser than 1MeV. The results for the pion knockout from mesonic clouds of individual nucleons are absolutely different. The latter results are presented both for pion and rho-meson clouds localized on nucleons.
The treatment of the $Δ$-current and its contribution in the exclusive $^{16}$O$(e,e'pp)^{14}$C and $^{16}$O$(γ,pp)^{14}$C knockout reactions are investigated in combination with the effects of correlations. Different parametrizations of the effective $Δ$-current and different treatments of correlations in the two-nucleon overlap function are considered. The results are presented and discussed for a suitable choice of kinematics. It is found that the investigation of different mutually supplementing kinematics is necessary to resolve the uncertainties in the theoretical ingredients and extract…
A theory of short-range correlations in two-nucleon removal due to elastic breakup (diffraction dissociation) on a light target is developed. Fingerprints of these correlations will appear in momentum distributions of back-to-back emission of the nucleon pair. Expressions for the momentum distributions are derived and calculations for reactions involving stable and unstable nuclear species are performed. The signature of short-range correlations in other reaction processes is also studied.
We study the effect of wave function orthogonality in the relativistic treatment of the nucleon removal reactions (gamma, p) and (e, e' p). The continuum wave function describing the outgoing nucleon is made orthogonal to the relevant bound states using the Gram-Schmidt procedure. This procedure has the advantage of preserving the asymptotic character of the continuum wave function and hence the elastic observables are unaffected. The orthogonality effects are found to be negligible for (e, e' p) reactions for missing momenta up to 700 MeV/c. This holds true for both parallel and perpendicular…
The polarization degrees-of-freedom in electronuclear two-nucleon knockout reactions are discussed. Model calculations for the unpolarized $^{16}$O(e,e$'$pp) cross sections at ($\mid \vec{q} \mid$,$ω$)=(210 MeV,300 MeV/c) are compared to recently obtained data. Predictions for the polarization observables in electronuclear two-nucleon knockout are presented. It is stressed that detailed studies of two-nucleon emission processes permit to constrain the contribution from two-nucleon mechanisms (like meson-exchange and isobar effects) to the single-nucleon knockout channel (e,e$'$p).
Knockout nuclear reactions, in which a nucleon is removed from a nucleus as a result of the collision with another nucleus, have been widely used as an experimental tool, both to populate isotopes further removed from stability, and to obtain information about the single-particle nature of the nuclear spectrum. In order to fully exploit the experimental information, theory is needed for the description of both the structure of the nuclei involved, and the dynamics associated with the nucleon removal mechanisms. The standard approach, using theoretical shell-model spectroscopic factors for the …
Knockout reactions with heavy ion targets in inverse kinematics, as well as "quasi-free" (p,2p) and (p,pn) reactions are useful tools for nuclear spectroscopy. We report calculations on \textit{ab-initio} many-body wavefunctions based on the no-core shell model to study the nucleon removal reactions in light nuclei, including beryllium, carbon, and oxygen isotopic chains, and explore the importance of using an \textit{ab-initio} method. Our study helps clarifying how the extraction of spectroscopic factors from the experiments depend on the details of the many-body wavefunctions being probed. …
Experimental studies of one nucleon knockout from magic nuclei suggest that their nucleon orbits are not fully occupied. This conflicts a commonly accepted view of the shell closure associated with such nuclei. The conflict can be reconciled if the overlap between initial and final nuclear states in a knockout reaction are calculated by a non-standard method. The method employs an inhomogeneous equation based on correlation-dependent effective nucleon-nucleon (NN) interactions and allows the simplest wave functions, in which all nucleons occupy only the lowest nuclear orbits, to be used. The m…
[Background] The neutrino-nucleus ($νA$) cross section is a major source of systematic uncertainty in neutrino-oscillation studies. A precise $νA$ scattering model, in which multinucleon effects are incorporated, is pivotal for an accurate interpretation of the data. [Purpose] In $νA$ interactions, meson-exchange currents (MECs) can induce two-nucleon ($2N$) knockout from the target nucleus, resulting in a two-particle two-hole (2p2h) final state. They also affect single nucleon ($1N$) knockout reactions, yielding a one-particle one-hole (1p1h) final state. Both channels affect the inclusive s…
We use the relativistic distorted-wave impulse approximation (RDWIA) to study the effects of negative-energy components of Dirac wave functions on the left-right asymmetry for (e,e'p) reactions on 16-O with 0.2 < Q^2 < 0.8 and 12-C with 0.6 < Q^2 < 1.8 (GeV/c)^2. Spinor distortion is more important for the bound state than for the ejectile and the net effect decreases with Q^2. Spinor distortion breaks Godon equivalence and the data favor the CC2 operator with intermediate coupling to the sea. The left-right asymmetry for Q^2 < 1.2 (GeV/c)^2 is described well by RDWIA calcuations, but at Q^2 =…
Results for the cross sections of the exclusive 16O(e,e'pn)14N and 16O(gamma,pn)14N knockout reactions are presented and discussed in different kinematics. In comparison with earlier work, a complete treatment of the center-of-mass (CM) effects in the nuclear one-body current is considered in connection with the problem of the lack of orthogonality between initial bound and final scattering states. The effects due to CM and orthogonalization are investigated in combination with different treatments of correlations in the two-nucleon overlap function and for different parametrizations of the tw…
Free nucleons propagating in water are known to produce gamma rays, which form a background to the searches for diffuse supernova neutrinos and sterile neutrinos carried out with Cherenkov detectors. As a consequence, the process of nucleon knockout induced by neutral-current quasielastic interactions of atmospheric (anti)neutrinos with oxygen needs to be under control at the quantitative level in the background simulations of the ongoing and future experiments. In this paper, we provide a quantitative assessment of the uncertainty associated with the theoretical description of the nuclear cro…
We present results of an updated calculation of the 2p2h (two particle two hole) contribution to the neutrino-induced charge-current cross section. We provide also some exclusive observables, interesting from the point of view of experimental studies, e.g. distributions of momenta of the outgoing nucleons and of available energy, which we compare with the results obtained within the NEUT generator. We also compute, and separate from the total, the contributions of 3p3h mechanisms. Finally, we discuss the differences between the present results and previous implementations of the model in MC ev…
In neutrino event generators, for models for neutrino and electron scattering only inclusive cross sections are implemented. When these models are used to describe a semi-inclusive cross section, the event generator attaches the hadron variables based on some assumptions. In this work we compare the nucleon kinematics given by the method used in the GENIE event generator, e.g. in the implementation of the SuSAv2 model, to a fully unfactorized calculation using the relativistic distorted wave impulse approximation (RDWIA). We focus on kinematics relevant to the $e4ν$ analysis and show that obse…
We investigate the factorization properties of the exclusive electroinduced two-nucleon knockout reaction $A(e,e'pN)$. A factorized expression for the cross section is derived and the conditions for factorization are studied. The $A(e,e'pN)$ cross section is shown to be proportional to the conditional center-of-mass (c.m.) momentum distribution for close-proximity pairs in a state with zero relative orbital momentum and zero radial quantum number. The width of this conditional c.m. momentum distribution is larger than the one corresponding with the full c.m. momentum distribution. It is shown …
Short-range correlations (SRC) in asymmetric nuclei with an unusual neutron-to-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 $p(A,p^{\prime} N_1 N_2)$ reactions. Our reaction model hinges on the factorization properties of SRC-driven $A(e, e^\prime N_1 N_2)$ 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}\…
Full Faddeev-type calculations are performed for one-neutron knockout reaction of $^{14}$Be on proton target at 69 MeV/u incident energy. Inclusive transverse momentum distributions for the outgoing ($^{12}$Be + n) system and semi-inclusive cross sections are presented. A significant proton-core single scattering contribution emerges where the valence neutron has non zero angular momentum relative to the core. This indicates that distorted-wave impulse approximation is inadequate and the complete multiple scattering series must be taken into account for the considered reaction. The magnitude o…
Within the framework of the relativistic distorted wave impulse approximation (DWIA), we investigate the sensitivity of complete sets of polarization transfer observables for exclusive proton knockout from the 3s$_{1/2}$, 2d$_{3/2}$ and 2d$_{5/2}$ states in $^{208}$Pb, at an incident laboratory kinetic energy of 202 MeV, and for coincident coplanar scattering angles ($28.0^{\circ}$, $-54.6^{\circ}$), to different distorting optical potentials, finite-range (FR) versus zero-range (ZR) approximations to the DWIA, as well as medium-modified meson-nucleon coupling constants and meson masses. Resul…
Final-state interactions in (e,e'n) knockout reactions in the quasi-free region are studied by considering the multistep direct scattering of the ejectile nucleon. Primary and multiple particle emission are included within the same model and are found to become important with increasing excitation energy. Charge-exchange effects taken into account through the two-step (e,e'p)(p,n) and three-step (e,e'p)(p,N)(N,n) processes are also found to increase with energy. A comparison with the results obtained with an isospin-dependent optical potential at small excitation energies is presented.
How Threshold Effects in Spectroscopic Factors Influence Heavy-Ion Knockout Reactions
Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所核科学理论南方中心）
Nucleon Correlations in Unstable Nuclei via Knockout Reactions
East Texas A&M University（东德克萨斯农工大学）；Technische Universität Darmstadt（达姆施塔特工业大学）；ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH（极端物质研究所EMMI，GSI重离子研究中心有限公司）
The longitudinal and transverse structure functions are calculated for inclusive electron scattering from ${}^{12}$C and ${}^{40}$Ca in the quasielastic and dip region. The microscopic model presented here incorporates two-body currents derived from one-pion exchange and intermediate $Δ$ excitation. The reaction mechanism involves both one-nucleon and two-nucleon knockout processes. It is demonstrated that, even for quasielastic kinematics, two-body currents give a substantial contribution to the transverse structure function. Furthermore, the observed excess of transverse strength in the dip …
The advent of new electron accelerators with few-GeV beam energies makes the (e,e'p) reaction a promising tool for investigating new aspects of the electromagnetic interaction. To this purpose it is crucial to set the scale of Final-State Interactions (FSI) at high ejectile energies. We have analyzed the constraints which allow for a meaningful generalization to (e,e'p) of the Glauber method used in elastic (p,p) scattering. The FSI dominance at large deflection angles produces in the distributions a universal behaviour resembling the coherent diffractive scattering between the ejected proton …
Background: Exclusive two-nucleon knockout after electroexcitation of nuclei ($A(e,e'NN)$ in brief) is considered to be a primary source of information about short-range correlations (SRC) in nuclei. For a proper interpretation of the data, final-state interactions (FSI) need to be theoretically controlled. Purpose: Our goal is to quantify the role of FSI effects in exclusive $A(e,e'pN)$ reactions for four target nuclei representative for the whole mass region. Our focus is on processes that are SRC driven. We investigate the role of FSI for two characteristic detector setups corresponding wit…
New experimental data obtained from $γ$-ray tagged one-neutron and one-proton knockout from $^{55}$Co is presented. A candidate for the sought-after $T=1, T_z = 0, J^π = 6^+$ state in $^{54}$Co is proposed based on a comparison to the new data on $^{54}$Fe, the corresponding observables predicted by large-scale-shell-model (LSSM) calculations in the full $fp$-model space employing charge-dependent contributions, and isospin-symmetry arguments. Furthermore, possible isospin-symmetry breaking in the $A=54$, $T=1$ triplet is studied by calculating the experimental $c$ coefficients of the isobaric…
Background: One-nucleon knockout reactions provide insightful information on the single-particle structure of nuclei. When applied to one-neutron halo nuclei, they are purely peripheral, suggesting that they could be properly modeled by describing the projectile within a Halo Effective Field Theory (Halo-EFT). Purpose: We reanalyze the one-neutron knockout measurements of $^{11}$Be and $^{15}$C-both one-neutron halo nuclei-on beryllium at about 60MeV/nucleon. We consider Halo-EFT descriptions of these nuclei which already provide excellent agreement with breakup and transfer data. Method: We i…
We consider high-energy quasifree single- and two-proton knockout reactions induced by electrons and protons and address the question what target-nucleus densities can be effectively probed after correcting for nuclear attenuation (initial- and final-state interactions). Our calculations refer to ejected proton kinetic energies of 1.5 GeV, the reactions (e,e'p), (γ,pp) and (p,2p) and a carbon target. It is shown that each of the three reactions is characterized by a distinctive sensitivity to the density of the target nucleus. The bulk of the (γ,pp) strength stems from the high-density regions…
We propose an effective current operator for nucleon electromagnetic knockout that incorporates spinor distortion and density-dependent nucleon form factors using an effective momentum approximation. This method can be used in a coordinate-space approach with either relativistic or nonrelativistic optical potentials and overlap functions. We studied these effects for the $^{16}O(\vec{e},e' \vec{p})$ reaction at Q^2 = 0.8 (GeV/c)^2. Spinor distortion substantially enhances the left-right asymmetry while reducing the ratio between sideways and longitudinal recoil polarization for p-shell knockou…
We propose a new approach to probe the spatial extension of the valence neutron orbital in the $^{9}$Be nucleus via the ${}^{9}$Be($p,pn$)${}^{8}$Be knockout reaction. This property of the nuclear molecular orbital has not been established in previous experimental studies and divergence exists between the theoretical descriptions of ${}^{9}$Be from different perspectives, \textit{i.e.}, the antisymmetrized molecular dynamics and the container pictures of cluster dynamics. These pictures are represented by two different well-proven microscopic models, the antisymmetrized molecular dynamics (AMD…
