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Stephenson, E.J.; Liu, J.; Bacher, A.D.; Bowyer, S.M.; Chang, S.; Olmer, C.; Wells, S. P.; Wissink, S. W.; Lisantti, J.

doi:10.1103/physrevlett.78.1636

Cited by 32 publications

(16 citation statements)

References 26 publications

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“…An IUCF experiment has reported evidence of a substantially reduced m ‫ء‬ r 0 , using polarized proton scattering on 28 Si [8]. An improvement between the data and calculations was observed if the r 0 mass is reduced by 20% in nuclear matter.…”

mentioning

confidence: 66%

“…Alternate explanations have been proposed [7] which also depend on a decrease of the r 0 meson mass. However, theoretical issues still remain open in such complex reactions [3].An IUCF experiment has reported evidence of a substantially reduced m ‫ء‬ r 0 , using polarized proton scattering on 28 Si [8]. An improvement between the data and calculations was observed if the r 0 mass is reduced by 20% in nuclear matter.…”

mentioning

confidence: 91%

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Probing theρ0Mass Modification in the Subthreshold Region on3He

1998

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An earlier measurement of the r 0 mass in the nuclear medium, reported by the TAGX Collaboration, indicated a substantial mass reduction of dm r 0 160 MeV͞c 2 in the 3 He͑g, p 1 p 2 ͒ reaction. In this Letter, we report the reanalysis of previously published data for the same reaction at lower photon energies, E g 380 700 MeV, which lie below the r 0 ! p 1 p 2 detection threshold unless the r 0 mass is significantly modified by the nuclear medium. We find the resulting mass shift in this region to be even larger, dm r 0 280 6 40 MeV͞c 2 , consistent with r 0 decay in the field of the nucleon as the dominant effect. [S0031-9007(98)06384-4] PACS numbers: 24.85.+p, 12.40.Yx, 25.20.Lj It has been established by chiral perturbation theory ͑xPT ͒ that, at infinite nuclear matter density, deconfinement of the quarks takes place and hadron masses are reduced to zero. Correspondingly, at some high nuclear matter density r c , partial restoration of chiral symmetry takes place [1]. One of the consequences of this restoration is a reduction of the vector meson masses within the nuclear medium, a topic that has been the focus of intense interest within the theoretical community, as outlined in a recent review [2]. There is qualitative agreement among most theoretical predictions that the renormalized vector meson mass is reduced in the nuclear medium.Several heavy ion collider experiments at CERN (CERES, HELIOS, and NA28), leading to dilepton production, indicate an enhanced production cross section in the lower dilepton invariant mass range of 200 600 MeV͞c 2 [3]. The spectral shapes are not well reproduced by theoretical calculations based on hadron decay after freeze out when employing free particle properties. The dominant p 1 p 2 annihilation mechanism fails to account for the observed excess dilepton production, and better agreement is found if the r 0 mass is modified [4], according to the scaling hypothesis of Brown and Rho [5], or according to quark sum rules (QSR) predictions [6]. Alternate explanations have been proposed [7] which also depend on a decrease of the r 0 meson mass. However, theoretical issues still remain open in such complex reactions [3].An IUCF experiment has reported evidence of a substantially reduced m ‫ء‬ r 0 , using polarized proton scattering on 28 Si [8]. An improvement between the data and calculations was observed if the r 0 mass is reduced by 20% in nuclear matter. This improvement, however, did not carry through to all of the observables. Questions can be raised regarding the interpretation of this result, such as the definition of mass when the r 0 is in the propagator, as well as the issue of r 0 -v interference, and the effect of the medium on the v mass. Recent Bonn results also indicate a significant reduction in the total photoabsorption cross section per nucleon on various nuclei [9], which could be explained by a corresponding decrease of the r 0 mass in nuclear medium. All such evidence of a r 0 mass renormalization is, however, indirect and inconclusive.A more conclusive an...

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confidence: 66%

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confidence: 91%

Probing theρ0Mass Modification in the Subthreshold Region on3He

1998

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“…Here we will present evidences for the predicted scaling in the meson masses. There are some preliminary experimental indications for decrease in matter of the ρ meson mass in recent nuclear experiments [83,84] but we expect more definitive results from future experiments at GSI and other laboratories. In fact, this is currently a hot issue in connection with the recent dilepton data coming from relativistic heavy ion experiments at CERN(European Organization for Nuclear Research).…”

Section: Mesons In Mediummentioning

confidence: 89%

Dense nuclear matter: Landau Fermi-liquid theory and chiral Lagrangian with scaling

Song

2001

Physics Reports

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The relation between the effective chiral Lagrangian whose parameters scale according to Brown and Rho scaling("BR scaling") and Landau Fermi-liquid theory for hadronic matter is discussed in order to make a basis to describe the fluctuations under the extreme condition relevant to neutron stars. It is suggested that BR scaling gives the background around which the fluctuations are weak. A simple model with BR-scaled parameters is constructed and reproduces the properties of the nuclear ground state at normal nuclear matter density successfully. It shows that the tree level in the model Lagrangian is enough to describe the fluctuations around BR-scaled background. The model Lagrangian is consistent thermodynamically and reproduces relativistic Landau Fermi-liquid properties. Such points are important for dealing with hadronic matter under extreme condition. On the other hand it is shown that the vector current obtained from the chiral Lagrangian is the same as that obtained from Landau-Migdal approach. We can determine the Landau parameter in terms of BR-scaled parameter. However these two approaches provide different results, when applied to the axial charge. The numerical difference is small. It shows that the axial response is not included properly in the LandauMigdal approach. 6The 3-body contributions to the energy per nucleon vs. Fermi momentum in the FTS models. The short-dashed line represents the contribution of the φ 3 term in the FTS2 with the Q1 parameters. The long-dashed and the solid lines represent the contributions of the cubic terms (φω 2 and φ 3 ) in the FTS1 with the T1 parameters for d = 2.7. 7The comparison of CERES dilepton experiments and the theoretical predictions with the free-mass mesons and with scaled mass mesons. The figure comes from [61]. 45 8 The in-medium ρ-meson mass and Z factor obtained in [66] for Γ t = 0. 47 9 E/A − M vs. ρ for FTS1 theory ("T1" parameter), the "S3", "B1" and "B3" models defined in Table 4.

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“…Other less directly related experimental conjectures of medium modifications of the ρ 0 mass have been deduced from an anomalous J/ψ suppression, reported by the NA50 collaboration for Pb + Pb collisions [15], enhanced K + -12 C scattering cross sections [16], and an IUCF experiment of polarized proton scattering on 28 Si, though in the latter the medium renormalization of the ρ 0 mass required for agreement with the data is inconsistent for different observables measured in the same experiment [17].…”

Section: A Relativistic Heavy Ion Resultsmentioning

confidence: 99%

Subthresholdρ0photoproduction on3He

Kagarlis¹,

Papandreou²,

Huber³

et al. 1999

Phys. Rev. C

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A large reduction of the ρ 0 mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction 3 He(γ,π + π − )X with a 10% duty factor tagged-photon beam and the TAGX multi-particle spectrometer. The energy range covered (800≤Eγ ≤1120 MeV) lies mostly below the free ρ 0 production threshold, a region which is believed sensitive to modifications of light vector-meson properties at nuclear-matter densities. The ρ 0 masses extracted from the MC fitting of the data, m * ρ 0 = 642±40, 669±32, and 682±56 MeV/c 2 for Eγ in the 800-880, 880-960, and 960-1040 MeV regions respectively, are independently corroborated by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-1 field driven theoretical predictions, may be suggestive of ρ 0 decay within the range of the nucleonic field.

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Effective IsovectorNNInteraction Strengths Determined from theS28i(

Cited by 32 publications

References 26 publications

Probing theρ0Mass Modification in the Subthreshold Region on3He

Probing theρ0Mass Modification in the Subthreshold Region on3He

Dense nuclear matter: Landau Fermi-liquid theory and chiral Lagrangian with scaling

Subthresholdρ0photoproduction on3He

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