共查询到20条相似文献,搜索用时 31 毫秒
1.
G. E. Volovik 《JETP Letters》2004,79(3):101-105
According to the Multiple Point Principle, our Universe is on the coexistence curve of two or more phases of the quantum vacuum. The coexistence of different quantum vacua can be regulated by the exchange of the global fermionic charges between the vacua, such as baryonic, leptonic, or family charge. If the coexistence is regulated by the baryonic charge, all the coexisting vacua exhibit the baryonic asymmetry. Due to the exchange of the baryonic charge between the vacuum and matter, which occurs above the electroweak transition, the baryonic asymmetry of the vacuum induces the baryonic asymmetry of matter in our Standard Model phase of the quantum vacuum. The present baryonic asymmetry of the Universe indicates that the characteristic energy scale, which regulates the equilibrium coexistence of different phases of quantum vacua, is about 106 GeV. 相似文献
2.
We examine the role of relativistic finite baryon volume effect in the phase transition between hadronic matter and quark-gluon plasma at vanishing baryon density. It is found that the appearance of abnormal state at high temperature may enhance the baryon-antibaryon excitation, which has large influence on the quark-gluon plasma formation. The numerical results show that the occurence of this phase transition depends on how to extrapolate the nucleon-scalar meson coupling constant to the baryonic resonance-scalar meson coupling. 相似文献
3.
The features of a hot and dense gas of quarks that are considered as quasiparticles of a model Hamiltonian with four-fermion
interaction are studied. Adapted to the Nambu-Jona-Lasinio model, this approach allows us to accommodate a phase transition
similar to the nuclear liquid-gas one. Arguments are given in favor of the statement that a plausible scenario of (partial)
chiral-symmetry restoration (even at zero temperature) in such a system could be a mixed phase of the vacuum and normal baryonic
matter. The properties of the transition layer separating the two media in question are also discussed. 相似文献
4.
Soma Sanyal 《Pramana》2003,61(5):1033-1037
Baryon number inhomogeneities may be generated during the epoch when the baryon asymmetry of the universe is produced, e.g.
at the electroweak phase transition. These lumps will have a lower temperature than the background. Also the value ofT
c
will be different in these regions. Since a first-order quark-hadron (Q–H) transition is susceptible to small changes in
temperature, we investigate the effect of the presence of such baryonic lumps on the dynamics of the Q–H transition. We find
that the phase transition is delayed in these lumps for significant overdensities. Consequently, we argue that baryon concentration
in these regions grows by the end of the transition. We mention some models which may give rise to such high baryon overdensities
before the Q–H transition. 相似文献
5.
U. Katscher J. A. Maruhn W. Greiner I. N. Mishustin 《Zeitschrift für Physik A Hadrons and Nuclei》1993,346(3):251-252
We present the excitation function of the reaction Au+Au in the frame work of the recently developed (2+1)-fluid model. In the (2+1)-fluid model, it is assumed that two baryonic fluids formed by the projectile and target nucleons produce a third hadronic fluid via inelastic nucleon-nucleon collisions. For this third fluid we use the equation of state of an interacting hadron gas obtained within the relativistic mean field model, including a first order phase transition. The dependence of the pion mean transverse momentum is investigated to observe the predicted plateau in the region of the phase transition of the hadronic matter to the quark-gluon plasma. 相似文献
6.
A qualitative analysis of the chiral phase transition in QCD with two massless quarks and nonzero baryon density is performed. It is assumed that, at zero baryonic density, ρ=0, the temperature phase transition is of the second order. Due to a specific power dependence of baryon masses on the chiral condensate, the phase transition becomes of the first order at the temperature T=Tph(ρ) for ρ>0. At temperatures Tcont(ρ)> T>Tph(ρ), there is a mixed phase consisting of the quark phase (stable) and the hadron phase (unstable). At the temperature T=Tcont(ρ), the system experiences a continuous transition to the pure chirally symmetric phase. 相似文献
7.
P. Costa C. A. de Sousa M. C. Ruivo Yu. L. Kalinovsky 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):842-844
We study the chiral phase transition at finite T and μ
B within the framework of the SU(3) Nambu-Jona-Lasinio (NJL) model. The QCD critical end point (CEP) and the critical line at finite temperature and baryonic
chemical potential are investigated: the study of physical quantities, such as the baryon number susceptibility near the CEP,
will provide complementary information concerning the order of the phase transition. We also analyze the information provided
by the study of the critical exponents around the CEP. 相似文献
8.
An extended quark sigma model which includes higher-order mesonic interactions is studied at the finite baryonic chemical potential u B and temperature T. The field equations have been solved in the mean-field approximation by using the modified iteration method at finite baryonic chemical potential u B and temperature T. The Goldstone theorem is satisfied below a critical temperature in the chiral limit for u B = 0. As expected from general universality, the chiral phase transition is second-order. By including the higher-order mesonic interactions, the critical temperature is reduced compared to that found in recent works and is in good agreement with lattice QCD results. The nucleon mass is examined in the (u B , T) plane, showing a strong dependence on u B and T. We find that an increase in both the baryonic chemical potential u B and the temperature T leads to an increase in the values of the nucleon mass. This is evidence for the quark-gluon deconfinement phase transition at higher values of temperature. 相似文献
9.
《Physics letters. [Part B]》1986,169(4):337-342
The dynamical process of the cosmological quark-hadron phase transition is investigated under the assumption of a weakly first-order phase transition. In particular the characteristic mass of these nuggets is determined to be smaller than 1019 g, using a spatial correlation function of the trapped quark phase. Furthermore, the possibility of these nuggets being left as isothermal baryonic clouds with very high density (δϱb/ϱb ∼ 5.0×1012) after evaporation is pointed out, and its cosmological implications are discussed. 相似文献
10.
K. A. Bugaev M. I. Gorenstein V. I. Zhdanov 《Zeitschrift fur Physik C Particles and Fields》1988,39(3):365-370
Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition. 相似文献
11.
K. A. Bugaev M. I. Gorenstein V. I. Zhdanov 《The European Physical Journal C - Particles and Fields》2005,39(3):365-370
Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations
of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition. 相似文献
12.
K. A. Bugaev R. Emaus V. V. Sagun A. I. Ivanytskyi L. V. Bravina D. B. Blaschke E. G. Nikonov A. V. Taranenko E. E. Zabrodin G. M. Zinovjev 《Physics of Particles and Nuclei Letters》2018,15(3):210-224
Using the most advanced formulation of the hadron resonance gas model we analyze the two sets of irregularities found at chemical freeze-out of central nuclear-nuclear collisions at the center of mass energies 3.8–4.9 GeV and 7.6–9.2 GeV. In addition to previously reported irregularities at the collision energies 4.9 and 9.2 GeV we found sharp peaks of baryonic charge density. Also we analyze the collision energy dependence of the modified Wroblewski factor and the strangeness suppression factor. Based on the thermostatic properties of the mixed phase of a 1st order phase transition and the ones of the Hagedorn mass spectrum we explain, respectively, the reason of observed chemical equilibration of strangeness at the collision energy 4.9 GeV and above 8.7 GeV. It is argued that the both sets of irregularities possibly evidence for two phase transitions, namely, the 1st order transition at lower energy range and the 2nd order transition at higher one. In combination with a recent analysis of the light nuclei number fluctuations we conclude that the center of mass collision energy range 8.8–9.2 GeV may be in the nearest vicinity of the QCD tricritical endpoint. The properties of the phase existing between two phase transitions are revealed and discussed. 相似文献
13.
K. A. Bugaev 《Physics of Particles and Nuclei Letters》2011,8(9):907-911
On the basis of exactly solvable models with the tricritical and critical endpoints I discuss the physical mechanism of endpoints
formation which is similar to the usual liquids. It is demonstrated that the necessary condition for the transformation of
the 1-st order deconfinement phase transition into the 2-nd order phase transition at the (tri)critical endpoint is the vanishing
of surface tension coefficient of large/heavy QGP bags. Using the novel model of the confinement phenomenon I argue that the
physical reason for the cross-over appearance at low baryonic densities is the negative value of QGP bag surface tension coefficient.
This implies the existence of highly non-spherical or, probably, even fractal surfaces of large and heavy bags at and above
the cross-over, which, perhaps, can be observed via some correlations. The model with the tricritical endpoint predicts that
at the deconfinement transition line the volume (mass) distribution of large (heavy) QGP bags acquires the power law form
at the endpoint only, while in the model with the critical endpoint such a power law exists inside the mixed phase. The role
of finite width of QGP bags is also discussed. 相似文献
14.
We examine baryonic matter at a quark chemical potential of the order of the confinement scale μ(q)~Λ(QCD). In this regime, quarks are supposed to be confined but baryons are close to the "tightly packed limit" where they nearly overlap in configuration space. We show that this system will exhibit a percolation phase transition when varied in the number of colors N(c): at high N(c), large distance correlations at the quark level are possible even if the quarks are essentially confined. At low N(c), this does not happen. We discuss the relevance of this for dense nuclear matter, and argue that our results suggest a new "phase transition," varying N(c) at constant μ(q). 相似文献
15.
Nonlinear theory of electrostatic baryonic waves in ambiplasma 总被引:1,自引:0,他引:1
A. E. Dubinov S. K. Saikov A. P. Tsatskin 《Journal of Experimental and Theoretical Physics》2011,112(6):1051-1060
A collisionless nonmagnetized ambiplasma consisting of Maxwellian gases of protons, antiprotons, electrons, and positrons
is considered. The dispersion relation for electrostatic baryonic waves is derived and analyzed and exact expressions for
the linear wave phase velocities are obtained. Two types of such waves are shown to be possible in ambiplasma: acoustic and
plasma ones. Analysis of the dispersion relation has allowed the ranges of parameters in which nonlinear solutions should
be sought in the form of solitons to be found. A nonlinear theory of baryonic waves is developed and used to obtain and analyze
the exact solution to the basic equations. The analysis is performed by the method of a fictitious potential. The ranges of
phase velocities of periodic baryonic waves and soliton velocities (Mach numbers) are determined. It is shown that in the
plasma under consideration, these ranges do not overlap and that the soliton velocity cannot be lower than the linear velocity
of the corresponding wave. The profiles of physical quantities in a periodic wave and a soliton (wave scores) are plotted. 相似文献
16.
A. N. Kiseleva 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(6):727-730
The experiment on study of compressed baryonic matter (CBM) will be one of the main ones in the future Facility of Antiproton and Ion Research (FAIR) in Darmstadt, Germany. The CBM experiment is aimed at investigating the phase diagram of quantum chromodynamics in the range of high baryonic densities, using high-energy nuclear collisions. One of the main experiments will be detection of the muon decay channel of vector mesons with the aim of studying their nuclear modifications. The results of simulation of possible measurements are reported here. 相似文献
17.
《Nuclear Physics A》1997,622(4):605-619
The (σ, ω) model in the mean-field approximation where the meson fields are treated classically, describes much of observed nuclear structure and has been employed to describe the nuclear equation of state up to the quark-gluon phase transition. The acceleration of the meson sources, for example, in relativistic heavy-ion collisions, should result in bremsstrahlung-like radiation of the meson fields. The many mesons emitted serve to justify the use of classical meson fields. The slowing of the nuclei during the collision is modeled here as a smooth transition from initial to final velocity. Under ultra-relativistic conditions, vector radiation dominates. The angular distribution of energy flux shows a characteristic shape. It appears that if the vector meson field couples to the conserved baryon current, independent of the baryonic degrees of freedom, this mechanism will contribute to the radiation seen in relativistic heavy-ion collisions. The possible influence of the quark-gluon plasma is also considered. 相似文献
18.
The connection between the sigma model of Lee and Wick and the Nambu-Jona-Lasinio (NJL) model is discussed. It is shown that the sigma field potential of the linear Lee-Wick model is identical in form with the variation of the vacuum energy of the NJL system with the baryonic scalar densityn s. The sigma field is proportional ton s. Furthermore, the coupling constant and mass of thisσ field are fully determined by the NJL model version of the Goldberger-Treiman relation. It is shown further that the restoration of chiral symmetry with increasing baryonic density always occurs via a second order transition in the NJL model, while it is necessarily of first order in the associated linear Lee-Wick model. 相似文献
19.
J. Cleymans K. Redlich H. Satz E. Suhonen 《Zeitschrift fur Physik C Particles and Fields》1993,58(2):347-355
We consider two scenarios for the expansion of a quark-gluon plasma. If the evolution is slow enough, the system can remain in equilibrium throughout its entire history up to the freeze-out of a hadron gas; for a very rapid expansion, it may break up into hadrons before or at the confinement transition, without ever going through an equilibrium hadron phase. We compare hadron production rates in the two approaches and show that for a hadronisation temperatureT?200 MeV and baryonic chemical potential μ B ?500 MeV, their predictions essentially coincide. Present data on strange particle production lead to values in this range and hence cannot provide a distinction between the two scenarios. Pion, nucleon and non-strange meson production seem to require a considerably lower freeze-out temperature and baryonic chemical potential. In the hadron gas picture, this is in accord with the difference in mean free path of the different hadrons in the medium; it suggests a sequential freeze-out, in which strange hadrons stop interacting earlier than non-strange hadrons. In the quark-gluon plasma break-up, the hadronic final state fails to provide the high entropy per baryon observed in non-strange hadron production. The break-up moreover leads to a decrease of the entropy per baryon; hence it must be conceptually modified before it can be considered as a viable hadronisation mechanism. 相似文献
20.
S. M. Piyadin A. N. Khrenov A. A. Terekhin A. Yu. Isupov V. P. Ladygin Yu. V. Gurchin A. N. Livanov J. Lukstins A. K. Kurilkin P. K. Kurilkin S. G. Reznikov T. A. Vasiliev 《Physics of Particles and Nuclei Letters》2012,9(8):589-592
The results of the first extraction of the 3.42 A GeV 12C beam at Nuclotron and its transportation to the experimental area is presented. It is demonstrated that the beam parameters are sufficient for the first phase of the experiments on the studies of the dense baryonic matter at Nuclotron. 相似文献