### Regular Series

#### JUBILEE ISSUE

Preface

Wounded Nucleons, Wounded Quarks: A Personal Story

Acta Phys. Pol. B 51, 1023 (2020)

page 1023 •

abstract

One of the authors of the idea of “wounded” nucleons and quarks recalls the origin and development of this concept.

Brief History of the Search for Critical Structures in Heavy-ion Collisions

Acta Phys. Pol. B 51, 1033 (2020)

page 1033 •

abstract

The paper briefly presents history, status, and plans of the search for the critical structures — the onset of fireball, the onset of deconfinement, and the deconfinement critical point — in high-energy nucleus–nucleus collisions. First, the basic ideas are introduced, the history of the observation of strongly interacting matter in heavy-ion collisions is reviewed, and the path towards the quark–gluon plasma discovery is sketched. Then the status of the search for critical structures is discussed — the discovery of the onset of deconfinement, indications for the onset of fireball, and still inconclusive results concerning the deconfinement critical point. Finally, an attempt to formulate priorities for future measurements — charm quarks versus the onset of deconfinement and detailed study of the onset of fireball — closes the paper.

A Pedagogical Discussion of Quarkyonic Matter and Its Implication for Neutron Stars

Acta Phys. Pol. B 51, 1067 (2020)

page 1067 •

abstract

This paper is a brief pedagogical review of the ideas that motivate the concept of Quarkyonic Matter. If $N_{\mathrm {c}}$ is the number of quark colors, baryonic matter at very high density and low temperature remains confining to density scales of the order of $N_{\mathrm {c}}^{3/2} {\mit \Lambda }_{\mathrm {QCD}}^3$ that is parametrically larger than that of the QCD scale ${\mit \Lambda }_{\mathrm {QCD}}^3$. This implies that a description of nuclear matter will involve both quark and confined degrees of freedom. I argue that the equation of state of Quarkyonic Matter should be very hard, and the sound velocity should rise very rapidly from its small value at nuclear matter densities to a value of the order of 1 at a few times nuclear matter density.

Acta Phys. Pol. B 51, 1079 (2020)

page 1079 •

abstract

We discuss the causes which can limit the accuracy of the predictions based on the conventional PDFs when including in global parton analyses the data at moderate scales $\mu$. The first is the existence of power corrections ${\cal O} (Q_0^2/\mu ^2)$ due to the double counting of contributions arising from the region below the input scale $Q_0$. The second concerns the possible inclusion of the BFKL re-summation of the $(\alpha _{\mathrm {s}}\ln (1/x))^n$ terms. The third is the treatment of the heavy-quark thresholds. We show how to include the heavy-quark masses ($m_h$ with $h=c,b,t$) in DGLAP evolution which provides the correct smooth behaviour through the threshold regions and how to subtract the low parton virtuality $|k^2|\lt Q^2_0$ contributions from the DIS and Drell–Yan NLO coefficient functions in order to avoid the double counting.

Fractional Brownian Motions

Acta Phys. Pol. B 51, 1097 (2020)

page 1097 •

abstract

Properties of different models of fractional Brownian motions are discussed in detail. We shall collect here several possible ways of introducing and defining various possible fBms, discuss their properties, find how they are similar, and how they differ. In particular, we shall try to find what mechanisms or details in their definitions make these motions anomalous and whether can the various models be distinguished experimentally. To this aim, the main tool used here will be the autocorrelation function $C(t,s)$, and related to it characteristics: nonmarkovian behaviour and so-called weak ergodicity breaking.

Many Faces of Non-equilibrium: Anomalous Transport Phenomena in Driven Periodic Systems

Acta Phys. Pol. B 51, 1131 (2020)

page 1131 •

abstract

We consider a generic system operating under non-equilibrium conditions. Explicitly, we consider an inertial classical Brownian particle dwelling a periodic structure with a spatially broken reflection symmetry. The particle is coupled to a bath at the temperature $T$ and is driven by an unbiased time-periodic force. In the asymptotic long-time regime, the particle operates as a Brownian motor exhibiting finite directed transport although no net biasing force acts on the system. Here, we review and interpret in further detail our own recent research on the peculiar transport behaviour for this set-up. The main focus is put on those different emerging Brownian diffusion anomalies. Particularly, within the transient, time-dependent domain, the particle is able to exhibit anomalous diffusive motion which eventually crosses over into normal diffusion only in the asymptotic long-time limit. In the latter limit, this normal diffusion coefficient may even show a non-monotonic temperature dependence, meaning that it is not monotonically increasing with increasing temperature, but may exhibit instead an extended, intermediate minimum before growing again with increasing temperature.

Strongly Correlated Quantum Matter: A Subjective Overview of Selected Fundamental Aspects

Acta Phys. Pol. B 51, 1147 (2020)

page 1147 •

abstract

In this brief overview, I address some of the fundamental topics related to the physics of strongly correlated fermions, which have been also the subject of my research. After addressing the question why the field has a fundamental meaning, we next turn to the specific problems with their simple theoretical description. Those topics are: (i) the concept of spin-dependent masses of heavy particles and its subsequent experimental verification; (ii) the correlated metal–insulator transitions of the Mott–Hubbard-type; (iii) real space pairing and its subsequent experimental verification for high-temperature superconducting cuprates. I mention also the persistence of quantum spin and charge excitations in the superconducting phase. All those phenomena confirm the view that the strongly correlated fermionic systems represent a new class of quantum liquids, with some properties quantitatively different than those of the Landau Fermi liquids. Namely, they can be classified as those that fall in between those of the anomalous Landau Fermi liquid and localized-magnetic-moment system.

Probability Distribution for the First Casimir Operator $C_1$ in the Quantum Coulomb Field

Acta Phys. Pol. B 51, 1185 (2020)

page 1185 •

abstract

Probability distribution for the first Casimir operator $C_1$ in the quantum Coulomb field is calculated from first principles of quantum theory of the Coulomb field formulated by the Author. This is followed by a certain, I hope novel, formulation of probabilistic interpretation of Quantum Mechanics, which allows to avoid lots of “philosophical” talk about Quantum Mechanics. This talk is very voluminous but not necessarily enlightening.

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