Spectral function at high missing energies and momenta

Frick, T.; Hassaneen, Khaled S. A.; Rohe, D.; Müther, H.

doi:10.1103/physrevc.70.024309

Cited by 25 publications

(32 citation statements)

References 15 publications

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“…The main characteristics pre- * Email: C.Barbieri@gsi.de † Present address: Gesellschaft für Schwerionenforshung, Planckstr. 1, 64291, Darmstadt, Germany dicted by these calculations are confirmed by recent experimental data [11,12,13], which will be considered further below. Locating this strength experimentally, at both large E m and p m , is difficult because it is spread over an energy range of several hundred MeV, so the total density of the spectral function is very low.…”

supporting

confidence: 72%

“…Recently, the experimental strength measured for 12 C in parallel kinematics was compared to theory [11,12]. For missing energies up to 200 MeV, the summed strength measured turned out to agree with theoretical predictions.…”

mentioning

confidence: 93%

“…Thus, the most important for the present analysis. As stated above, theoretical calculations can reproduce the qualitative shape of this distribution and the total summed strength but miss the position peak [12]. As we are mainly interested in the reaction mechanism, it is preferable to parameterize the SRC part of the input spectral function in terms of a Lorentzian energy distribution, which was fitted to the experimental results for 12 C in parallel kinematics [23].…”

mentioning

confidence: 99%

“…New data were subsequently taken by the E97-006 collaboration at Jefferson Lab [21,11,12] for a set of nuclei ranging from carbon to gold. Both optimal (parallel) and perpendicular kinematics were used, to provide useful data for investigating the reaction mechanism.…”

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confidence: 99%

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Final state interactions in electron scattering at high missing energies and momenta

Barbieri

2006

Nuclear Physics B - Proceedings Supplements

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Calculations of two-step rescattering and pion emission for the 12 C(e, e ′ p) reaction at very large missing energies and momenta are compared with recent data from TJNAF. For parallel kinematics, final state interactions are strongly reduced by kinematical constraints. A good agreement between calculation and experiment is found for this kinematics when one admits the presence of high momentum components in the nuclear wave function. In recent years, electron scattering experiments have been possible with kinematics that involve large energies and momentum transfered, as for example in studies of nuclear transparency. In this regime, the final state interactions (FSI) for the knock out of a nucleon are usually treated employing Glauber inspired calculations [1,2,3,4]. Such techniques, together with the experience gained in related nuclear structure studies, provide a useful starting point to pursue accurate predictions of neutrino-nucleus interactions at high energy. This was pointed out by various contributions to this conference.At scattering energies of the order of GeV, the leptoninc probe can resolve the high-momentum tail of the spectral function generated by shortrange (central and tensor) correlations (SRC). This represent about 10-20% of the total spectral strength [5,6] and is found along a ridge in the momentum-energy plane (k-E) which spans a region of several hundred MeV/c (MeV) [7,9,8]. This corresponds to large missing momenta (p m ) and energies (E m ) in knock out cross sections. This contribution to the spectral function is also responsible for most of the binding energy of nuclear systems [10]. The main characteristics pre- * Email: C.Barbieri@gsi.de † Present address: Gesellschaft für Schwerionenforshung, Planckstr. 1, 64291, Darmstadt, Germany dicted by these calculations are confirmed by recent experimental data [11,12,13], which will be considered further below. Locating this strength experimentally, at both large E m and p m , is difficult because it is spread over an energy range of several hundred MeV, so the total density of the spectral function is very low. In this energy regime multi-nucleon processes, beyond the direct knock out, are possible [14] and can induce large shifts in the missing energies and momenta, moving strength to regions where the direct signal is much smaller and therefore submerging it. As it will be discussed below, the effects of FSI become larger and less controllable when the transverse structure functions that enter the expression of the (e, e ′ p) cross section dominate the longitudinal one. This trend is predicted by several theoretical studies [14,15,16,17,18]. The issue of how to control FSI in lepton scattering experiments has been discussed in detail in Ref. [19,20] for the particular case of kinematics sensitive to the SRC tail of the nuclear spectral function. A Monte Carlo simulation and kinematical arguments led to the suggestion that the best chance for an identification of SRC occurs in parallel kinematics 3 .3 In this work we refer to 'paralle...

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supporting

confidence: 72%

mentioning

confidence: 93%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Final state interactions in electron scattering at high missing energies and momenta

Barbieri

2006

Nuclear Physics B - Proceedings Supplements

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“…[15], it was suggested that the contribution of rescattering can be diminished by choosing parallel kinematics and taking advantage of modern electron beam facilities. New data were subse-quently taken in these conditions by the E97-006 collaboration at Jefferson Laboratory [8,16,17] for a set of nuclei ranging from carbon to gold. Clearly, FSI could still play a role even in parallel kinematics and need to be properly addressed before the relevant physical information is extracted from the experiment.…”

Section: Introductionmentioning

confidence: 99%

Effects of rescattering in(e,e′p)reactions within a semiclassical model

Barbieri

Lapikás²

2004

Phys. Rev. C

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The contribution of rescattering to final state interactions in ͑e , eЈp͒ cross sections is studied for medium and high missing energies using a semiclassical model. This approach considers two-step processes that lead to the emission of both nucleons. The effects of nuclear transparency are accounted for in a Glauber-inspired approach and the dispersion effects of the medium at low energies are included. It is found that rescattering is strongly reduced in parallel kinematics. At high missing energies and momenta, the distortion of the shortrange correlated tail of the spectral function is dominated by a rearrangement of that strength itself. In perpendicular kinematics, a further enhancement of the experimental yield is due to strength that is originally in the mean field region. This contribution becomes negligible at large missing momenta.

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Dynamical response functions in correlated fermionic systems

2005

Self Cite

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Response functions in nuclear matter at finite temperature are considered beyond the usual Hartree-Fock (HF) plus Random Phase Approximation (RPA) scheme. The contributions due to the propagator for the dressed nucleons and the corresponding vertex corrections are treated in a consistent way. For that purpose a semi-realistic Hamiltonian is developed with parameters adjusted to reproduce the nucleon self-energy as derived from realistic nucleon-nucleon interactions. For a scalar residual interaction the resulting response functions are very close to the RPA response functions. However, the collective modes, if present, get an additional width due to the coupling to multi-pair configurations. For isospin dependent residual interactions we find strong modifications of isospin response functions due to multi-pair contributions in the response function. Such a modification can lead to the disappearance of collective spin or isospin modes in a correlated system and shall have an effect on the absorption rate of neutrinos in nuclear matter

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Spectral function at high missing energies and momenta

Cited by 25 publications

References 15 publications

Final state interactions in electron scattering at high missing energies and momenta

Final state interactions in electron scattering at high missing energies and momenta

Effects of rescattering in(e,e′p)reactions within a semiclassical model

Dynamical response functions in correlated fermionic systems

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