### Regular Series

#### Vol. 35 (2004), No. 12, pp. 2817 - 3114

Acta Phys. Pol. B 35, 2817 (2004)

page 2817 •

abstract

Soft multiparticle production in hadron-hadron collisions is reviewed with particular emphasis on its role as a standard for heavy-ion collisions at SPS and RHIC energies and as a bridge interpolating between the most simple $e^+e^-$ and the most complex $AA$ collisions.

Structure and Fine Structure in Multiparticle Production Data at High Energies

Acta Phys. Pol. B 35, 2873 (2004)

page 2873 •

abstract

A summary is given of data on the longitudinal rapidity and pseudorapidity distributions observed in $e^+e^-$, $pp$, $pA$ and $AA$ collisions at high energies. The remarkable simplicity and universality observed in the data and its relevance to the study of the high energy density system produced in heavy ion collisions is discussed.

Hydro-Inspired Parameterizations of Freeze-Out in Relativistic Heavy-Ion Collisions

Acta Phys. Pol. B 35, 2895 (2004)

page 2895 •

abstract

Popular parameterizations of the freeze-out conditions in relativistic heavy-ion collisions are discussed. Similarities and differences between the blast-wave model and the single-freeze-out model, both used recently to interpret the RHIC data, are outlined. A non-boost-invariant extension of the single-freeze-out model is proposed and applied to describe the recent BRAHMS data.

Acta Phys. Pol. B 35, 2911 (2004)

page 2911 •

abstract

We introduce the equilibrium and non-equilibrium statistical hadronization picture of particle production in ultra-relativistic heavy ion collisions. We describe the related physical reaction scenarios, and show how these can lead to quark pair yield non-equilibrium. Using the SHARE1.2 program suite we quantitatively model particle yields and ratios for RHIC-130 run. We study how experimental particle ratios can differentiate between model scenarios, and discuss in depth the importance of hadronic resonances in understanding of hadron production processes.

The Transverse Energy and the Charged Particle Multiplicity in a Statistical Model with Expansion

Acta Phys. Pol. B 35, 2929 (2004)

page 2929 •

abstract

Global variables such as the transverse energy and the charged particle multiplicity and their ratio are evaluated, in a statistical model with expansion, for heavy-ion collisions from AGS to RHIC at $\sqrt {s_{NN}}=200$ GeV. Full description of decays of hadron resonances is applied. The predictions of the model done at the freeze-out parameters established independently from observed particle yields and $p_{\rm T}$ spectra agree well with the experimental data. However, some (explicable) overestimation of the ratio has been found.

The Phase Diagram of QCD and the Critical Point

Acta Phys. Pol. B 35, 2939 (2004)

page 2939 •

abstract

The properties of the QCD phase diagram and the physics of the QCD critical point are reviewed.

New Resonances at Belle

Acta Phys. Pol. B 35, 2963 (2004)

page 2963 •

abstract

I summarise Belle results on new discoveries in meson spectroscopy. Two broad $D^{**}$ mesons that are $P$-wave excitations of the $c \bar {u}$ system as well as two narrow $D_{{\rm s}J}$ states interpreted as orbitally excited $P$-wave $c\bar {s}$ states have been observed. Moreover, the $X(3872)$ charmonium-like state has been discovered. Mass of this state being very near $M_{D} + M_{D^{\star }}$ mass threshold could indicate molecular nature of newly observed state.

Restoration of Chiral Symmetry in Excited Hadrons

Acta Phys. Pol. B 35, 2985 (2004)

page 2985 •

abstract

Physics of the low-lying and high-lying hadrons in the light flavor sector is reviewed. While the low-lying hadrons are strongly affected by the spontaneous breaking of chiral symmetry, in the high-lying hadrons the chiral symmetry is restored. A manifestation of the chiral symmetry restoration in excited hadrons is a persistence of the chiral multiplet structure in both baryon and meson spectra. Meson and baryon chiral multiplets are classified. A relation between the chiral symmetry restoration and the string picture of excited hadrons is discussed.

Introduction to Chiral Doubling of Heavy–Light Hadrons

Acta Phys. Pol. B 35, 3021 (2004)

page 3021 •

abstract

In this lectures we review the main idea of the chiral doublers scenario, originating from simultaneous constraints of chiral symmetry and of heavy quark spin symmetry on effective theories of heavy–light hadrons. We discuss chiral doublers for mesons and (briefly) chiral doublers for baryons in light of recent experimental data.

Pentaquarks: Introduction and Review

Acta Phys. Pol. B 35, 3039 (2004)

page 3039 •

abstract

This review and critique of the experimental searches for pentaquarks follows the lectures given at the Zakopane summer school in May 2004. This is a rapidly changing field, and the viewpoint of the present article is according to the state of the results known at the time the lectures were given. A brief review of the theoretical motivation for the recent experimental results is also presented.

Pentaquarks

Acta Phys. Pol. B 35, 3055 (2004)

page 3055 •

abstract

I discuss the recent experimental and theoretical developments following the discovery of the ${\mit \Theta }^+$ pentaquark — an exotic $uudd\bar s$ baryon resonance observed in the $KN$ channel by several experiments, and an exotic ${\mit \Xi }^{*--}$ ($dd ss \bar u$) reported by NA49 at CERN. I focus on the theoretical interpretation of the data, both in terms of quark and chiral degrees of freedom, on the predictions for related exotic states, and on several unresolved questions raised by the experimental data, such why some experiments observe the pentaquarks and other do not, the apparently extremely narrow width of the ${\mit \Theta }^+$ and the determination of its parity. I also describe the likely properties of the proposed heavy-quark pentaquarks — an anticharmed exotic baryon ${\mit \Theta }_c$ ($uudd\bar c$) and ${\mit \Theta }_b^+$, ($uudd \bar b$), which are expected to be extremely narrow or even stable against strong decays. H1 recently reported observation of a possible ${\mit \Theta }_c$ candidate in $D^{*-} p$ channel. Pentaquarks are also being searched for in $e^+e^-$ annihilation and $\gamma \gamma$ collisions in the LEP data and at $B$-factories.

Nonlinear Evolution Equations in QCD

Acta Phys. Pol. B 35, 3069 (2004)

page 3069 •

abstract

These lectures are an introduction to the phenomenon of partonic saturation and nonlinear evolution equations in Quantum Chromodynamics. After short introduction to linear evolution, the problem of unitarity bound and parton saturation are discussed. The nonlinear Balitsky–Kovchegov evolution equation in the high energy limit is introduced and the progress in understanding the properties of its solution is reviewed. We discuss saturation scale, geometrical scaling and lack of infrared diffusion. Finally, we give a brief summary of current theoretical developments which go beyond the Balitsky–Kovchegov equation.

Physics of Parton Saturation

Acta Phys. Pol. B 35, 3103 (2004)

page 3103 •

abstract

Basic ideas related to the description of a dense gluonic system in a nucleon, motivated by high energy scattering experiments at HERA and RHIC, are presented.

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