Using the Beth–Uhlenbeck Approach to Describe the Kaon to Pion Ratio in a 2 + 1 Flavor PNJL Model

Blaschke, D.; Friesen, A. V.; Kalinovsky, Yu. L.; Radzhabov, A. E.

doi:10.3390/particles3010014

Cited by 6 publications

(7 citation statements)

References 25 publications

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“…For the HRG model, see Figures 1 and 4 of reference [65], where the similarity of the K + /π + ratio with the Wroblewski factor λ s = 2 ss /( uū + dd ) was noticed. For the PNJL model, this behaviour has been shown in Figure 7 of [34] in the BW approximation and in Figure 3 of [66] for the BU approach. The lines of constant K − /π − ratio have the opposite slope and cross the freezeout line only once, thus forming a monotonously rising function of the increasing freezeout temperature (or √ s N N ).…”

Section: "Horn" Effect In the Kaon-to-pion Ratiomentioning

confidence: 72%

“…6 vs. 7) plays no decisive role in the description of the kaon-to pion ratios. This is understood because the horn originates from the relative positions of the almost straight lines of the kaon-to-pion ratios and their slope to the curved freezeout line in the phase diagram while the presence or absence of the critical point has no effect on these features (see the corresponding figures in references [34,66,72]).…”

Section: "Horn" Effect In the Kaon-to-pion Ratiomentioning

confidence: 99%

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Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke

Friesen

Kalinovsky

et al. 2020

Eur. Phys. J. Spec. Top.

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Within the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature T and baryochemical potential μB. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the T − μB plane as a proxy for the chemical freezeout line, whereby the variable x = T∕μB is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using x-dependent pion and strange quark potentials. A sharp “horn” effect in the energy dependence K+∕π+ ratio is explained by the enhanced pion production at energies above √sNN=8 GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

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Section: "Horn" Effect In the Kaon-to-pion Ratiomentioning

confidence: 72%

Section: "Horn" Effect In the Kaon-to-pion Ratiomentioning

confidence: 99%

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke

Friesen

Kalinovsky

et al. 2020

Eur. Phys. J. Spec. Top.

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show abstract

“…7 of [34] in the BW approximation and in Fig. 3 of [66] for the BU approach. The lines of constant K − /π − ratio have the opposite slope and cross the freezeout line only once, thus forming a monotonously rising function of the increasing freezeout temperature (or…”

Section: "Horn" Effect In the Kaon-to-pion Ratiomentioning

confidence: 96%

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke,

Friesen,

Kalinovsky

et al. 2020

Preprint

View full text Add to dashboard Cite

Within the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature T and baryochemical potential µB. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the T − µB plane as a proxy for the chemical freezeout line, whereby the variable x = T /µB is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using x-dependent pion and strange quark potentials. A sharp "horn" effect in the energy dependence K + /π + ratio is explained by the enhanced pion production at energies above √ sNN = 8 GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

show abstract

“…where E = M 2 + p 2 , g(E) = (e E/T − 1) −1 is the Bose function and δ M (M ) is in-medium phase shift in the meson channel M calculated within the PNJL model [14,15]. In order to relate the model results with the actual phenomenology of chemical freeze-out in heavy-ion collisions we use the idea to map points with a fixed value of µ/T on the line in phase diagram of our PNJL model to points on the curve fitted to statistical model analyses.…”

Section: Beth-uhlenbeck Approach To the "Horn" Effectmentioning

confidence: 99%

QCD Phase Diagram at NICA energies: $K^+/π^+$ horn effect and light clusters in THESEUS

Blaschke¹,

Friesen²,

Ivanov³

et al. 2020

Preprint

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We discuss recent progress in the development of the three-fluid hydrodynamics-based program THESEUS towards an event generator suitable for applications to heavy-ion collisions at the intermediate energies of the planned NICA and FAIR experiments. We follow the strategy that modifications of particle distributions at the freeze-out surface in the QCD phase diagram may be mapped directly to the observable ones within a sudden freeze-out scheme. We report first results of these investigations for the production of light clusters (deuterons and tritons) which can be compared to experimental data from the HADES and the NA49 experiment and for the interpretation of the "horn" effect observed in the collision energy dependence of the K + /π + ratio. Medium effects on light cluster production in the QCD phase diagram are negligible at the highest NICA energies but shall play a dominant role at the lowest energies. A sharp "horn"-type signal in the K + /π + ratio can be obtained when the onset of Bose condensation modelled by a pion chemical potential results in an enhancement of pions at low momenta (which is seen at LHC energies) and would occur already in the NICA energy range.

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Using the Beth–Uhlenbeck Approach to Describe the Kaon to Pion Ratio in a 2 + 1 Flavor PNJL Model

Cited by 6 publications

References 25 publications

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

QCD Phase Diagram at NICA energies: $K^+/π^+$ horn effect and light clusters in THESEUS

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