Metastable exotic multihypernuclear objects

Schaffner, J.; Greiner, Carsten; Stöcker, H.

doi:10.1103/physrevc.46.322

Cited by 161 publications

(158 citation statements)

References 57 publications

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“…= 0.621 and x a z = 0.375, which agrees rather well with RH1, if one takes into consideration that the nucleonic sector was parametrized differently, namely via using NL-SH [9]. But also the stronger couplings may be possible according to the fits of Schaffner et al [12]. If one uses an RHapproach with density-dependent couplings adjusted to the outcome of our RBHF-calculations, one needs a slightly lower x a A = 0.59 in order to obtain the correct lowest binding energy of A in 17 0, [20].…”

Section: Rhf -Approximation Rh3supporting

confidence: 70%

“…In the RH-scheme, zVs usually do not occur, since due to the large p-coupling, needed to reproduce the correct symmetry coefficients, the charge-favoured but isospin-unfavoured A~ is suppressed [1,3]. Since the data from the hypernuclei are not yet conclusive with respect to the hyperon couplings (for more details, see [11,12]), it is common in more modern investigations to use the SU(6) symmetry for the vector couplings and adjust the (j-coupling with respect to the lowest hyperon level in nuclear matter. However, the data from hypernuclei still permit a large bandwidth for the couplings [1, 6, 11 -13].…”

Section: M=<7ujirp6mentioning

confidence: 99%

“…The horizontal line gives the mass of the pulsar PSR 1913+16. X^H = 0.8 (x aH < 0.72) gives the highest value for the coupling constant compatible with properties of hypernuclei [12,20], from the standard picture of a high strangeness component, which may be a special feature of the RHapproximation with a large /?-coupling (for details, see [1]). The chosen parametrizations are given in Table 3.…”

Section: Rhf -Approximation Rh3mentioning

confidence: 99%

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Compatibility of Neutron Star Masses and Hyperon Coupling Constants

Huber

Weigel

Weber

1999

Zeitschrift Für Naturforschung A

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It is shown that the modern equations of state for neutron star matter based on microscopic calculations of symmetric and asymmetric nuclear matter are compatible with the lower bound on the maximum neutron-star mass for a certain range of hyperon coupling constants, which are constrained by the binding energies of hyperons in symmetric nuclear matter. The hyperons are included by means of the relativistic Hartree-or Hartree-Fock approximation. The obtained couplings are also in satisfactory agreement with hypernuclei data in the relativistic Hartree scheme. Within the relativistic Hartree-Fock approximation, hypernuclei have not been investigated so far.PACS 97.60.7d, 26.60,+c, 21.80.+a, 21.65.+f Neutron star matter (NSM), bound by gravity, differs from high density nuclear matter produced in heavy ion reactions in several respects: 1) Since the repulsive Coulomb force is much stronger than the gravitational attraction, NSM is much more asymmetric than terrestrial matter in heavy ion collisions.2) The weak interaction time scale is small in comparison with the lifetime of the neutron star (NS), but large in comparison with the lifetime of high-density matter in heavy ion reactions. For that reasons dense matter in high-energy reactions has to obey the constraints of isospin symmetry and strangeness conservation whereas NSM is a charge neutral system with no strangeness conservation (see, for instance, [1] ax) = Y, B=p,n,l±° ,A,E°---,A--C°B(x)+with further references). Extraterrestrial NSM is for that reasons a rather theoretical object with a very complex structure. Since its density stretches over an enormous range, reaching from crystalline iron on the surface to several times of nuclear matter saturation density in the core, one encounters in the theoretical descriptions many obstacles, for which one has to introduce theoretical assumptions and extrapolations [1, 2], However one can try to combine both high density systems in a common theory, which is possible in modern field theoretical approaches. The first systematic investigation in this respect was performed by Glendenning [3], who used the standard nuclear relativistic Lagrangian extended by inclusion of hyperons and deltas, i. e. M=<7,UJ,IR,P,6

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Section: Rhf -Approximation Rh3supporting

confidence: 70%

Section: M=<7ujirp6mentioning

confidence: 99%

Section: Rhf -Approximation Rh3mentioning

confidence: 99%

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Compatibility of Neutron Star Masses and Hyperon Coupling Constants

Huber

Weigel

Weber

1999

Zeitschrift Für Naturforschung A

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“…The production of strange quark matter and/or hypermatter in central heavy ion collisions has been suggested long ago, either in the form of multi-hypernuclear objects (strange hadronic matter) [1,2,3], or strangelets (strange multiquark droplets) [4,5,6,7,8]. The formation of the latter would be rather appealing, since it would be an unambiguous signature that a deconfined, strangeness rich state of quark gluon plasma has been created during the reaction.…”

Section: Introductionmentioning

confidence: 99%

Stability of strange quark matter: model dependence

Alberico¹,

Ratti²

2002

AIP Conference Proceedings

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The minimum energy per baryon number of strange quark matter is studied, as a function of the strangeness fraction, in the MIT bag model and in two different versions of the Color Dielectric Model: a comparison is made with the hyperon masses having the same strangeness fraction, and coherently calculated within both models. Calculations are carried out in mean field approximation, with one gluon exchange corrections. The results allow to discuss the model dependence of the stability of strangelets: they can be stable in the MIT bag model and in the double minimum version of the Color Dielectric Model, while the single minimum version of the Color Dielectric Model excludes this possibility.

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“…Strangelet formation has also been considered in coalescence models [9]. Strange quark matter could even occur as a decay product of metastable exotic multihypernuclear objects (MEMO's) [10]. The discovery of strangelets would have profound implications beyond the confirmation of the QGP formation: it would establish the existence of strange quark matter (SQM) [11][12][13] [20].…”

mentioning

confidence: 99%

Strangelet Search in Pb-Pb Interactions at 158 GeV/cper Nucleon

et al. 1996

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The NA52 experiment searches for long-lived massive strange quark matter particles, so-called strangelets, produced in Pb-Pb collisions at a beam momentum of p lab 158 A GeV͞c. Upper limits for the production of strangelets at zero degree production angle covering a mass to charge ratio up to 120 GeV͞c 2 and lifetimes t lab * 1.2 ms are given. The data presented here were taken during the 1994 lead beam running period at CERN. [S0031-9007(96) PACS numbers: 25.75. Dw, 12.38.Mh, 24.85.+p The production of strange quark matter (SQM), socalled strangelets, has long been advertised as an ultimate signature for quark-gluon plasma (QGP) formation in ultrarelativistic heavy ion collisions. Strangelets could be formed from the QGP via a strangeness distillation process [1][2][3][4]. Their production is due to a cooling process of the plasma which results in a strong enhancement of the s quarks in the quark phase. The cooling mechanism of the plasma is started by the evaporation of pions, K 1 and K 0 , which carry entropy and antistrangeness away from the system. The strong s-quark enhancement in the baryon rich environment of the plasma favors the formation of strangelets. In contrast to nuclear matter, strangelets consist of approximately the same number of u, d, and s quarks. On the basis of the Pauli exclusion principle such multiquark states become stable owing to the introduction of strangeness as an additional degree of freedom. Depending on the relative s-quark content, strangelets can exist in neutral or charged form. By virtue of the large s-quark content, the charge to mass ratio of strangelets is expected to be small ͑Z͞A , 0.1͒, which is used as a prominent experimental signature. Bag model calculations indicate that for sufficiently large masses ͑A . 10 GeV͞c 2 ͒ strangelets could be stable with respect to strong and weak nucleon emission and therefore detectable in mass spectrometer experiments [5][6][7][8]. Strangelet formation has also been considered in coalescence models [9]. Strange quark matter could even occur as a decay product of metastable exotic multihypernuclear objects (MEMO's) [10]. The discovery of strangelets would have profound implications beyond the confirmation of the QGP formation: it would establish the existence of strange quark matter (SQM) [11][12][13] [20]. A recent review is given in Ref. [21]. During the 1994 Pb period at CERN, the NA52 Collaboration took data to search for positively and negatively charged strangelets resulting from lead-on-lead collisions at an incident beam momentum of 158A GeV͞c. Preliminary results have been already presented [22]. Now the full statistics have been analyzed and the final results are reported here.The experimental setup (Fig. 1) makes use of the existing H6 beam line at the CERN-SPS to identify the secondary particles produced in the lead target. It is a single particle, double-bend focusing spectrometer transmitting charged particles within a momentum bite of 2.8% for rigidities p͞jZj selectable between 5 and 200 GeV͞c with full particle...

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Metastable exotic multihypernuclear objects

Cited by 161 publications

References 57 publications

Compatibility of Neutron Star Masses and Hyperon Coupling Constants

Compatibility of Neutron Star Masses and Hyperon Coupling Constants

Stability of strange quark matter: model dependence

Strangelet Search in Pb-Pb Interactions at 158 GeV/cper Nucleon

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