abstract

In this lecture, we discuss the properties of dense hadronic matter inside neutron stars. In particular, we pay attention to the role of strangeness in the core of neutron stars by analysing the presence of baryons and mesons with strangeness. We consider two interesting possible scenarios in their interior, that is, the existence of hyperons leading to the so-called hyperon puzzle and the presence of a kaon condensed phase inside neutron stars.

abstract

In this paper, an overview of kaonic atoms studies from the late 90s to nowadays at the DA\(\Phi \)NE collider at INFN-LNF is presented. Experiments on kaonic atoms are an important tool to test and optimize phenomenological models on the low-energy strong interaction. Since its construction, the DA\(\Phi \)NE collider has represented an ideal machine to perform kaonic atoms measurements, thanks to the unique beam of kaons coming from the \(\phi \)s produced in the collider decays. The DEAR and SIDDHARTA experiments achieved the precise evaluation of the shift and width of the \(2p\rightarrow 1s\) transition in kaonic hydrogen due to the strong interaction, and thus provided a measurement strictly linked to isospin-dependent antikaon–nucleon scattering lengths. To fully disentangle the iso-scalar and iso-vector scattering lengths, the measurement of kaonic deuterium is necessary as well. The SIDDHARTA-2 experiment is now taking data at the DA\(\Phi \)NE collider with the aim to fulfill the need of this measurement, and therefore provide important information to the various phenomenological models on low-energy strong interactions with strangeness. The SIDDHARTA-2 Collaboration is also exploring the possibility to perform future kaonic atoms experiments, developing X‑ray detector systems beyond the current state-of-art. These measurements are crucial for a deeper understanding of the kaon interactions with nuclei and for solving the kaon mass “puzzle”.

abstract

In this contribution, we review on-going and planned experimental programs addressing the study of the QCD phase diagram at high net-baryon densities. Several physics observables relevant for these investigations are discussed. Special emphasis is put on physics topics of interest in the energy region accessible at FAIR, currently under construction in Darmstadt, Germany.

abstract

These lecture notes consist of two major connected parts. The first part (Sections 1 and 2), after a brief historical introduction, deals with the physics of critical points in thermodynamic equilibrium. The features of the fluctuations relevant to the QCD critical point search are highlighted. The second part (Sections 3 and 4) focuses on the recent developments in the description of the fluctuation dynamics especially relevant to the QCD critical point search in heavy-ion collisions.