Quark deconfinement in compact stars through sexaquark condensation

In this contribution, we present for the first time a scenario according to which early quark deconfinement in compact stars is triggered by the Bose-Einstein condensation (BEC) of a light sexaquark (S) with a mass $m_S<2054$ MeV, that has been suggested as a candidate particle to explain the baryonic dark matter in the Universe. The onset of S BEC marks the maximum mass of hadronic neutron stars and it occurs when the condition for the baryon chemical potential $\mu_b=m_S/2$ is fulfilled in the center of the star, corresponding to $M_{\rm onset}\lesssim 0.7~M_\odot$. In the gravitational field of the star the density of the BEC of the S increases until a new state of the matter is attained, where each of the S-states got dissociated into a triplet of color-flavor-locked (CFL) diquark states. These diquarks are the Cooper pairs in the color superconducting CFL phase of quark matter, so that the developed scenario corresponds to a BEC-BCS transition in strongly interacting matter. For the description of the CFL phase, we develop here for the first time the three-flavor extension of the density-functional formulation of a chirally symmetric Lagrangian model of quark matter where confining properties are encoded in a divergence of the scalar self-energy at low densities and temperatures.Comment: 27 pages, 8 figures, Contribution to the Book "New Phenomena and New States of Matter in the Universe. From Quarks to Cosmos" edited by C. A. Z. Vasconcellos, P. O. Hess and T. Bolle

Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach

We describe multiquark clusters in quark matter within a Beth-Uhlenbeck approach in a background gluon field coupled to the underlying chiral quark dynamics using the Polyakov gauge which establishes the center symmetry of color SU(3) that suppresses colored states as an aspect of confinement. Quark confinement is modeled by a large quark mass in vacuum motivated by a confining density functional approach. A multiquark cluster containing $n$ quarks and antiquarks is described as a binary composite of smaller subclusters $n_1$ and $n_2$ ($n_1+n_2=n$). It has a spectrum consisting of a bound state and a scattering state continuum. For the corresponding cluster-cluster phase shifts we discuss simple ans\"atze that capture the Mott dissociation of clusters as a function of temperature and chemical potential. We go beyond the simple "step-up-step-down" model that ignores continuum correlations and introduce an improved model that includes them in a generic form. In order to explain the model, we restrict ourselves here to the cases where the cluster size is $1 \le n \le 6$. A striking result is the suppression of the abundance of colored multiquark clusters at low temperatures by the coupling to the Polyakov loop and their importance for a quantitative description of lattice QCD thermodynamics at non-vanishing baryochemical potentials. An important ingredient are Polyakov-loop generalized distribution functions of $n$-quark clusters which are derived here for the first time. Within our approach we calculate thermodynamic properties such as baryon density and entropy. We demonstrate that the limits of a hadron resonance gas at low temperatures and $\mathcal{O}(g^2)$ perturbative QCD at high temperatures are correctly reproduced. A comparison with lattice calculations shows that our model is able to give a unified, systematic approach to describe properties of the quark-gluon-hadron system.Comment: 20 pages, 11 figures, 6 table

How does dark matter affect compact star properties and high density constraints of strongly interacting matter

We study the impact of asymmetric bosonic dark matter on neutron starproperties, including possible changes of tidal deformability, maximum mass,radius, and matter distribution inside the star. The conditions at which darkmatter particles tend to condensate in the star's core or create an extendedhalo are presented. We show that dark matter condensed in a core leads to adecrease of the total gravitational mass and tidal deformability compared to apure baryonic star, which we will perceive as an effective softening of theequation of state. On the other hand, the presence of a dark matter haloincreases those observable quantities. Thus, observational data on compactstars could be affected by accumulated dark matter and, consequently,constraints we put on strongly interacting matter at high densities. To confirmthe presence of dark matter in the compact star's interior, and to break thedegeneracy between the effect of accumulated dark matter and stronglyinteracting matter properties at high densities, several astrophysical and GWtests are proposed.<br

Проблеми розгляду судами клопотань органів кримінального переслідування у зв’язку з набуттям чинності Закону № 2147-VIII від 03.10.2017 р.

Іваницький С. О. Проблеми розгляду судами клопотань органів кримінального переслідування у зв’язку з набуттям чинності Закону № 2147-VIII від 03.10.2017 р. / С. О. Іваницький // "Творчий шлях вченого: до 80-річчя професора В. В. Долежана" : матер. кругл. столу // Творчий шлях вченого: до 80-річчя професора В. В. Долежана / відп. ред. Н. М. Бакаянова ; уклад.: І. О. Кісліцина, М. О. Деменчук, С. І. Єленич ; МОН України, НУ "ОЮА". - Одеса : Юридична література, 2018. - С. 106-108

Hard-core Radius of Nucleons within the Induced Surface Tension Approach

In this work we discuss a novel approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons. Therefore, we perform a detailed analysis of its value which follows from hadronic and nuclear matter properties and find the most trustworthy range of its values: the hard-core radius of nucleons is 0.30--0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent.Comment: 12 pages, 4 figures, references added, typos correcte

Second virial coefficients of light nuclear clusters and their chemical freeze-out in nuclear collisions

Here we develop a new strategy to analyze the chemical freeze-out of light (anti)nuclei produced in high energy collisions of heavy atomic nuclei within an advanced version of the hadron resonance gas model. It is based on two different, but complementary approaches to model the hard-core repulsion between the light nuclei and hadrons. The first approach is based on an approximate treatment of the equivalent hard-core radius of a roomy nuclear cluster and pions, while the second approach is rigorously derived here using a self-consistent treatment of classical excluded volumes of light (anti)nuclei and hadrons. By construction, in a hadronic medium dominated by pions, both approaches should give the same results. Employing this strategy to the analysis of hadronic and light (anti)nuclei multiplicities measured by ALICE at $\sqrt{s_{NN}} =2.76$ TeV and by STAR at $\sqrt{s_{NN}} =200$ GeV, we got rid of the existing ambiguity in the description of light (anti)nuclei data and determined the chemical freeze-out parameters of nuclei with high accuracy and confidence. At ALICE energy the nuclei are frozen prior to the hadrons at the temperature $T = 175.1^{+2.3}_{-3.9}$ MeV, while at STAR energy there is a single freeze-out of hadrons and nuclei at the temperature $T = 167.2 \pm 3.9$ MeV. We argue that the found chemical freeze-out volumes of nuclei can be considered as the volumes of quark-gluon bags that produce the nuclei at the moment of hadronization.Comment: 15 pages, 4 figures, 3 table