Hadrons in dense matter

The quark-meson-coupling model is used to study droplet formation from the liquid-gas phase transition in cold asymmetric nuclear matter. The critical density and proton fraction for the phase transition are determined in the mean field approximation. Droplet properties are calculated in the ThomasFermi approximation. The electromagnetic field is explicitly included and its effects on droplet properties are studied. The results are compared with the ones obtained with the NL1 parametrization of the non-linear Walecka model.

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“…For a list of applications of the model to a variety of nuclear phenomena and earlier studies within the QMC model, see Ref. [20].…”

Section: Introductionmentioning

confidence: 99%

Droplet formation in cold asymmetric nuclear matter in the quark–meson-coupling model

et al. 2000

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Chiral symmetry and nuclear matter equation of state

Santra

2001

Pramana - J Phys

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We investigate the effect on the nuclear matter equation of state (EOS) due to modification of meson and nucleon parameters in nuclear medium as a consequence of partial restoration of chiral symmetry. To get the EOS, we have used Brueckner-Bethe-Golstone formalism with Bonnpotential as two-body interaction and QCD sum rule and Brown-Rho scaling prescriptions for modification of hadron parameters. We find that EOS is very much sensitive to the meson parameters. We can fit, with two body interaction alone, both the saturation density and the binding energy per nucleon.

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Effect of in-medium hadron parameter modification on nuclear matter equation of state

Santra

Lombardo²

2000

Phys. Rev. C

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We investigate the effect on the nuclear matter equation of state ͑EOS͒ due to modification of meson and nucleon parameters in a nuclear medium as a consequence of the partial restoration of chiral symmetry. To get the EOS, we have used Brueckner-Bethe-Goldstone formalism with Bonn-B potential as a two-body interaction and QCD sum rule and Brown-Rho scaling prescriptions for modification of hadron parameters. We find that the EOS is very much sensitive to the meson parameters. We can fit, with the two-body interaction alone, both the saturation density and the binding energy per nucleon. PACS number͑s͒: 21.65.ϩf, 12.38.Aw It is becoming more and more clear now that the chiral symmetry of the QCD Lagrangian and its spontaneous breaking ͓1͔ play a very important role in determining the structure of low mass hadrons which are comprised of u, d, and s quarks, and instantons play a crucial role in hadron correlators in mediating the spontaneous chiral symmetry breaking ͓2,3͔. Physical confinement of quarks seems to play a lesser role. The spontaneous breaking of the chiral symmetry is signaled by the nonvanishing values in the physical vacuum of the quark and gluon condensates ͓4-6͔. Calculations based on chiral perturbation theory and the QCD sum rule ͑QSR͒ indicate that values of these condensates are reduced when the hadrons are put in a medium, hence giving rise to partial restoration of chiral symmetry ͓7,8͔. Thus, there is a lot of interest nowadays to understand the mechanism of partial restoration in the nuclear medium of the chiral symmetry of the QCD Lagrangian ͓9,10͔, and to isolate effects arising out of it, as it provides a handle to understand nonperturbative QCD phenomena. The most important consequence of chiral symmetry restoration has been identified as modification of hadron properties in nuclear matter ͓11,12͔. Experimental evidence towards this is believed to be a large excess of e ϩ e Ϫ pairs observed in the invariant mass region around 400 MeV in the 200A GeV central collisions of S on Au and W by CERES ͓13͔ and HELIOS ͓14͔ groups, respectively. This has been explained ͓11,15͔ by arguing that the rho meson mass in nuclear matter is reduced at the densities created in the collision. Theoretical studies towards this were triggered after pointing out by Brown and Rho ͓16͔, based on the restoration of scale invariance of QCD, that masses of hadrons would scale in nuclear medium aswhere the density dependent quantities are denoted by asterisks. m N , m V , and m denote the masses of nucleon, vector mesons ͑rho, omega͒, and sigma mesons, respectively. f * is the in-medium pion decay constant, which is expected to vanish at high density when chiral symmetry is completely restored. Therefore, the masses in Eq. ͑1͒ should decrease with increasing density. Quantitative estimations of the dependence of masses of hadrons with respect to density have been made in the quark meson coupling ͑QMC͒ model ͓17͔ and using the QSR approach ͓18͔. In both of these two approaches the behavior of vector meson mass var...

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Hadrons in dense matter

Cited by 3 publications

References 33 publications

Droplet formation in cold asymmetric nuclear matter in the quark–meson-coupling model

Droplet formation in cold asymmetric nuclear matter in the quark–meson-coupling model

Chiral symmetry and nuclear matter equation of state

Effect of in-medium hadron parameter modification on nuclear matter equation of state

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