In-medium kaon production at the mean-field level

Abstract

The in-medium mass and energy of kaons and antikaons are studied within the Relativistic Mean Field approach and compared with predictions from chiral models by taking care of kaon-nucleon scattering data. Implications for the subthreshold production of kaons and antikaons in heavy-ion collisions are discussed. We find only small corrections due to in-medium effects on the mean-field level for the relevant production processes for kaons. The production of kaons is even less favourable at high density due to repulsive vector interactions. We conclude that one has to go beyond mean-field approaches and take fluctuations and secondary production processes into account to explain the recently measured enhancement of kaon production at subthreshold energies. The situation is different for antikaons where in-medium effects strongly enhances their production rates. We also see strong in-medium modifications of the annihilation processes of antikaons and Λ's which might be visible in flow measurements. At high density, we predict that the threshold energy for antikaon and Λ production and annihilation become equal leading to similar numbers of antikaons and Λ's in the dense zone of a relativistic heavy ion collision.

The high-density symmetry energy in heavy ion collisions

“…asy-soft). It is seen that most of the realistic models 2) of the in-medium kaon mass in units of the free kaon mass for the ChPT model [11] (yellow) and the OBE/RMF model [12] (blue). The upper/lower curves are for K 0 /K + , the middle one for symmetric nuclear matter.…”

“…An issue has been the specification of the mean field for the kaons [10]. It has been modelled in chiral perturbations theory (ChPT, Nelson and Kaplan, [11]) or in the one-boson exchange model (OBE, [12]), and we test both options here, as discussed below (for details see ref. [13]).…”

ϕ decay: A relevant source forK−production at energies available at the GSI Schwerionen-Synchrotron (SIS)?

“…The systematic study of K ± subthreshold production yields, phase space distributions, and flow observables in relativistic heavy-ion collisions at various beam energies and for various system sizes and centralities has attracted much attention, in particular in the context of in-medium properties of K + and K − mesons [1][2][3][4][5][6][7][8][9][10]. Corresponding experiments have been the focus of studies by the KaoS [11][12][13][14][15] and FOPI [16][17][18][19][20] Collaborations over the last two decades, following up on the pioneering experiments at Bevalac [21].…”

“…Indeed, the combined analysis of K + and K − suggests that a substantial part of the observed K − mesons is due to a strangeness exchange mechanism [33]. Furthermore K + and K − exhibit distinctively different in-medium properties, both in theoretical approaches [1][2][3][4][5][6][7][8][9][10][31][32][33][34] and in experiments [11][12][13]15,18,19,22].…”

Kaonic modes in hyperonic matter and p-wave kaon condensation

“…Studies of kaon condensation stimulated theoretical investigations of in-medium kaon properties with reference to the kaon-nucleon scattering [18][19][20][21], kaonic atoms [22][23][24][25], and heavy-ion collisions [26][27][28][29][30]. The momentum dependence of kaon optical potentials in a nuclear medium has also been discussed, which may serve as unified understanding of these phenomena [31][32][33].…”