Phenomenological approach to baryon resonance damping in nuclei

Alberico, W. M.; Gervino, G.; Lavagno, Andrea

doi:10.1016/0370-2693(94)90460-x

Cited by 47 publications

(45 citation statements)

References 23 publications

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“…[2] and Alberico et al [3] have shown that this disappearance can be explained by an extra in-medium width of about 0.3 GeV for the higher resonances. Two reasons for this large width have been discussed.…”

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confidence: 99%

“…A lowering of the ρ meson strength has been predicted by various hadronic models and QCD sum rule analyses (for a summary and review see [6]). Also effects of collisional broadening of this resonance due to collisions with other baryons have been considered [2][3][4]. Both effects lead in lowest order in the density to an extra in-medium resonance width that is proportional to the nuclear density ρ [4,5,7].…”

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confidence: 99%

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In-medium broadening of nucleon resonances

Lehr

Mosel

2001

Phys. Rev. C

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We analyze the effects of an in-medium broadening of nucleon resonances on the exclusive photoproduction of mesons on nuclei as well as on the total photoabsorption cross sections in a transport calculation. We show that the resonance widths observed in semi-inclusive photoproduction on nuclei are insensitive to an in-medium broadening of nucleon resonances. This is due to a simple effect: the sizeable width of the nuclear surface and Fermi motion.PACS numbers: 25.20.Lj, 25.20.x One of the most obvious in-medium effects is the observed disappearance of the resonance structures in the second and third resonance region in the total photoabsorption cross section on nuclei [1]. Kondratyuk et al.[2] and Alberico et al. [3] have shown that this disappearance can be explained by an extra in-medium width of about 0.3 GeV for the higher resonances. Two reasons for this large width have been discussed. In [4,5] we have pointed out that the total in-medium width of the D 13 (1520) resonance could reflect a lowering of the ρ meson spectral strength. A lowering of the ρ meson strength has been predicted by various hadronic models and QCD sum rule analyses (for a summary and review see [6]). Also effects of collisional broadening of this resonance due to collisions with other baryons have been considered [2][3][4]. Both effects lead in lowest order in the density to an extra in-medium resonance width that is proportional to the nuclear density ρ [4,5,7].In a recent paper Krusche et al.[8] discuss their data on inclusive and semi-inclusive single π 0 production in the second resonance region. After subtracting a smooth background from the observed cross section these authors obtain a resonance contribution which they attribute to the D 13 (1520) nucleon excitation. This resonant part shows a width that is compatible with the free width of the D 13 (1520) when smeared over the Fermi momentum of the nucleons in the target nucleus (see Fig. 5 in [8]). This result seems to present a problem for explanations of the disappearance of this resonance in the photoabsorption experiments [1] in terms of an in-medium broadening of the D 13 resonance. Raising this problem has been the *

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confidence: 99%

In-medium broadening of nucleon resonances

Lehr

Mosel

2001

Phys. Rev. C

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“…The most natural choice, given the flavor composition of deltas, is the universal coupling choice which consists in assuming x σΔ = x ωΔ = x ρΔ = 1. There have been many theoretical and experimental studies on the excitations of delta resonances in nuclear matter by means of electron and pion scattering and photoabsorption processes [24][25][26][27][28][29][30]. A general conclusion one can draw from these studies is that these particles feel, in the nuclear medium, a non-relativistic binding potential larger than the the nucleon's one, of the order of 30 MeV larger.…”

Section: Equation Of State For δ Isobarsmentioning

confidence: 99%

Delta isobars in neutron stars

Pagliara

Drago

Lavagno

et al. 2015

EPJ Web of Conferences

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Abstract. The appearance of delta isobars in beta-stable matter is regulated by the behaviour of the symmetry energy at densities larger than saturation density. We show that by taking into account recent constraints on the density derivative of the symmetry energy and the theoretical and experimental results on the excitations of delta isobars in nuclei, delta isobars are necessary ingredients for the equations of state used for studying neutron stars. We analyze the effect of the appearance of deltas on the structure of neutron stars: as in the case of hyperons, matter containing delta is too soft for allowing the existence of 2M neutron stars. Quark stars on the other hand, could reach very massive configurations and they could form from a process of conversion of hadronic stars in which an initial seed of strangeness appears through hyperons.

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“…Resonance contribution to γ − A cross-section for photon energy < ∼ 1.2 GeV has been estimated by using the prescription given in [19].…”

Section: Pacsmentioning

confidence: 99%

“…No medium effect on the φ meson is considered here as it is expected to be small [25]. At lower energies γ − A interaction is known to be dominated by resonance production [19,26]. Beyond this region we have used VMD for a better description.…”

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Shadowing in photoabsorption: Role of in-medium hadrons

Alam

Ghosh²,

Roy³

et al. 2002

Phys. Rev. C

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We study the effects of in-medium hadronic properties on shadowing in photon-nucleus interactions in Glauber model as well as in the multiple scattering approach. A reasonable agreement with the experimental data is obtained in a scenario of downward spectral shift of the hadrons. Shadowing is found to be insensitive to the broadening of the spectral functions. An impact parameter dependent analysis of shadowing might shed more light on the role of in-medium properties of hadrons. Nos. : 25.20.Dc,25.40.Ep,24.10.Ht,12.40.Vv Theoretical studies based on various models of hadronic interaction predict a reduction in the mass of hadrons at or above nuclear matter density [1,2]. The observation of enhanced dilepton production in the low invariant mass domain in the heavy ion collision experiments [3] does seem to indicate a non-trivial modification of the properties of light vector mesons, particularly the ρ meson, in hot and/dense medium [4]. However, the complicated dynamics both in the initial as well as final states in these experiments inhibits a firm conclusion about nuclear medium effects at present. PACSOn the other hand, the experiments like photoabsorption on nuclei provide much cleaner systems for the study of in-medium properties of mesons [5]. With the availability of better photon beams, there has been a renewed interest in the photo-absorption processes.The phenomena of shadowing plays an important role in the photo-nuclear reactions. The photo-nuclear data at lower energies, for different nuclei, seem to indicate an early onset of shadowing [6,7]. In ref.[8] this feature has been interpreted as a signature for a lighter ρ-meson in the medium, where the shadowing effect was evaluated within a Glauber-Gribov multiple scattering theory [9,10,11] and generalized vector meson dominance (VMD). In contrast the authors in ref. [12] have claimed that the early onset of shadowing can be understood within simple Glauber theory [11,13,14,15] if one takes the negative real part of the ρN scattering amplitude into account which corresponds to a higher effective inmedium ρ meson mass. In a subsequent paper [16], the authors have concluded that the enhancement of shadowing at low energies occurs due to lighter ρ mesons as well as intermediate π 0 produced in non-forward scattering. In the backdrop of these different inferences, we have made an attempt to understand the role of in-medium properties of hadrons in the phenomenon of shadowing in photo-nuclear reactions. The shadowing in photonnucleus reactions can be written as,where σ γA = Aσ γN + δσ γA consists of the incoherent scattering of the photon from individual nucleons and a correction due to the coherent interaction with several nucleons.The later has been evaluated using both multiple scattering approach [10,16,17] as well as Glauber's formula along with VMD [18]. Resonance contribution to γ − A cross-section for photon energy < ∼ 1.2 GeV has been estimated by using the prescription given in [19].Let us first consider the in-medium effects on the kinematic...

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Phenomenological approach to baryon resonance damping in nuclei

Cited by 47 publications

References 23 publications

In-medium broadening of nucleon resonances

In-medium broadening of nucleon resonances

Delta isobars in neutron stars

Shadowing in photoabsorption: Role of in-medium hadrons

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