High-Density QCD and Instantons

Rapp, Ralf; Schäfer, Thomas; Shuryak, Edward; Velkovsky, M.

doi:10.1006/aphy.1999.5991

Cited by 246 publications

(360 citation statements)

References 49 publications

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“…On the other hand, it must be noted that any dimuon source which happens to give, in the acceptance of the spectrometer, differential distributions similar to the ones calculated for open charm, should be taken as an equally probable source of the observed excess. Theoretical work on this subject is presently in progress, and alternative explanations to open charm enhancement have been proposed, including the production of thermal dimuons [32,33,34], or rescattering of D-mesons in nuclear matter [35], which may lead to a local enhancement in the acceptance of the spectrometer. Further work along these lines is being carried out inside the collaboration and will be the subject of future publications.…”

Section: Discussionmentioning

confidence: 99%

Dimuon and charm production in nucleus-nucleus collisions at the CERN-SPS

Abreu

2000

Eur. Phys. J. C

129

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Muon pair production in p-A, S-U and Pb-Pb collisions has been studied by the NA38 and NA50 collaborations at the CERN SPS. In this paper we present an analysis of the dimuon invariant mass region between the φ and the J/ψ. After subtraction of the combinatorial background due to π and K decays, we find that the superposition of dimuons from semi-leptonic decays of D mesons and from the Drell-Yan process reproduces well the mass and transverse momentum spectra measured in p-A collisions. From the yield of open charm dimuons required to fit our data we extract a charm production cross section in good agreement with previous measurements. A linear extrapolation of the p-A sources with the product of the mass numbers of the projectile and target nuclei, A×B, underestimates the yield measured in S-U and Pb-Pb collisions. The excess increases with the number of participant nucleons, and the ratio between the observed dimuon yield and the expected sources reaches a factor 2 for central Pb-Pb interactions. The kinematical distributions of the measured dimuon excess are compatible with those expected from the open charm contribution.

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Section: Discussionmentioning

confidence: 99%

Dimuon and charm production in nucleus-nucleus collisions at the CERN-SPS

Abreu

2000

Eur. Phys. J. C

129

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“…However, for the highest densities with quark chemical potential greater than 400 MeV the up, down, and strange quarks of all colours form Cooper pairs. This case is called the colour-flavour locked (CFL) phase (Alford et al 1999;Rapp et al 2000). Due to the required quark chemical potentials of μ q > 300 MeV and temperatures of T < 100 MeV (Rüster et al 2005) it is assumed that colour superconductivity is realized in the interior of strange and hybrid stars.…”

Section: Quark Matter In Compact Starsmentioning

confidence: 99%

Pulsar kicks by anisotropic neutrino emission from quark matter in strong magnetic fields

Sagert¹,

Schaffner-Bielich²

2008

A&A

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Aims. We critically discuss a pulsar acceleration mechanism based on asymmetric neutrino emission from the direct quark Urca process in the interior of proto neutron stars. Methods. The neutrinos are emitted by the cooling strange quark matter core with an anisotropy caused by a strong magnetic field. We calculate the kick velocity of the proto neutron star in dependence of the temperature and radius of the quark phase. The results are compared with the necessary magnetic field strength, as well as the neutrino mean free path. Results. We find that within a quark phase radius of 10 km and temperatures higher than 5 MeV kick velocities of 1000 km s −1 can be reached only when neutrino quark scattering is ignored. When taking the neutrino mean free paths in quark matter into account kick velocities higher than 100 km s −1 cannot be reached. The same holds even when effects from colour superconductivity are included. For pulsar kicks powered by quark phase transitions from an ungapped quark phase to the CFL phase the final velocity depends crucially on the pairing gap and the quark chemical potential and reaches 1000 km s −1 only in marginal cases. Conclusions. We find that the phenomenon of pulsar kick velocities higher than 100 km s −1 cannot be explained by asymmetric neutrino emission from either cooling normal strange quark or colour superconducting quark matter due to the small neutrino mean free paths. If neutrinos are produced by a phase transition to colour-superconducting quark matter, high kick velocities can only be reached for temperatures below 1 MeV.

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“…In such a way, on the basis of NJL-type models with two quark flavors it was shown that the color superconducting (2SC) phase might be yet present at rather small values of µ ∼ 350 MeV, i.e. at baryon densities only several times larger, than the density of ordinary nuclear matter (see reviews [3,4]). (For simplicity, throughout the paper we will study quark matter, composed from two quark flavors, i.e.…”

Section: Introductionmentioning

confidence: 99%

Mesons and diquarks in the color neutral superconducting phase of dense cold quark matter

2005

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The spectrum of meson and diquark excitations of dense color neutral cold quark matter is investigated in the framework of a 2-flavored Nambu-Jona-Lasinio type model, including a quark µ-and color µ8 chemical potential. It was found out that in the color superconducting (2SC) phase, i.e. at µ > µc = 342 MeV, µ8 aquires rather small values ∼ 10 MeV in order to ensure the color neutrality. In this phase the π-and σ meson masses are evaluated around ∼ 330 MeV. The spectrum of scalar diquarks in the color neutral 2SC phase consists of a heavy (SUc(2)-singlet) resonance with mass ∼ 1100 MeV, four light diquarks with mass 3|µ8|, and one Nambu -Goldstone boson which is in accordance with the Goldstone theorem. Moreover, in the 2SC phase there are five light stable particles as well as a heavy resonance in the spectrum of pseudo-scalar diquarks. In the color symmetric phase, i.e. for µ < µc, a mass splitting of scalar diquarks and antidiquarks is shown to arise if µ = 0, contrary to the case of µ = 0, where the masses of scalar antidiquarks and diquarks are degenerate at the value ∼ 700 MeV. If the coupling strength in the pseudo-scalar diquark channel is the same as in the scalar diquark one (as for QCD-inspired NJL models), then in the color symmetric phase pseudo-scalar diquarks are not allowed to exist as stable particles.

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High-Density QCD and Instantons

Cited by 246 publications

References 49 publications

Dimuon and charm production in nucleus-nucleus collisions at the CERN-SPS

Dimuon and charm production in nucleus-nucleus collisions at the CERN-SPS

Pulsar kicks by anisotropic neutrino emission from quark matter in strong magnetic fields

Mesons and diquarks in the color neutral superconducting phase of dense cold quark matter

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