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W. Broniowski

Publications and source records attributed to W. Broniowski.

At least 19 recordsLinked to original sources
arXiv2017

Excited Hadrons and Quark-Hadron Duality

We review how Quark-Hadron Duality (QHD) for (u,d) flavors at high energies and in the scaling regime suggests a radial and angular behaviour of mesonic and baryonic resonance masses of the Regge form $M^2_{nJ} = μ^2 n + β^2 J + M_0^2 $. The radial mass dependence is asymptotically consistent with a common two-body dynamics for mesons and baryons in terms of the quark-antiquark ($q \bar q)$ and quark-diquark ($qD$) degrees of freedom, respectively. This formula is validated phenomenologically within an uncertainty determined by half the width of the resonances, $ΔM_{nJ}^2 \sim Γ_{nJ} M_{nJ}$. With this error prescription we find from the non-strange PDG hadrons different radial slopes $μ^2_{\bar qq}=1.34(4) {\rm GeV}^2$ and $μ^2_{qD}=0.75(3) {\rm GeV}^2$, but similar angular slopes $β_{\bar q q}^2 \sim β_{ q D}^2 \sim 1.15 {\rm GeV}^2$.

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arXiv2017

Workshop on Excited Hyperons in QCD Thermodynamics at Freeze-Out (YSTAR2016) Mini-Proceedings

This Workshop brought top experts, researchers, postdocs, and students from high-energy heavy ion interactions, lattice QCD and hadronic physics communities together. YSTAR2016 discussed the impact of "missing" hyperon resonances on QCD thermodynamics, on freeze-out in heavy ion collisions, on the evolution of early universe, and on the spectroscopy of strange particles. Recent studies that compared lattice QCD predictions of thermodynamic properties of quark-gluon plasma at freeze-out with calculations based on statistical hadron resonance gas models as well as experimentally measured ratios between yields of different hadron species in heavy ion collisions provide indirect evidence for the presence of "missing" resonances in all of these contexts. The aim of the YSTAR2016 Workshop was to sharpen these comparisons and advance our understanding of the formation of strange hadrons from quarks and gluons microseconds after the Big Bang and in todays experiments at LHC and RHIC as well as at future facilities like FAIR, J-PARC and KL at JLab. It was concluded that the new initiative to create a secondary beam of neutral kaons at JLab will make a bridge between the hardron spectroscopy, heavy-ion experiments and lattice QCD studies addressing some major issues related to thermodynamics of the early universe and cosmology in general.

hep-ph↗
arXiv2014

Non-uniform phases in a three-flavour 't Hooft extended Nambu-Jona--Lasinio model

The possible existence of non-uniform phases in cold dense quark matter in the light quark sector ($u$, $d$ and $s$) is addressed using the Nambu-Jona--Lasinio Model extended to include flavour-mixing 't Hooft determinant. The effect of changes in the coupling strengths of the model is discussed. It is seen that the inclusion of the strange sector catalyses the appearance of these non-uniform phases extending the domain for their appearance.

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arXiv2014

Nonuniform phases in a three-flavor Nambu--Jona-Lasinio model

It is shown that flavor mixing of the strange and light quarks allows for existence of a much larger baryonic chemical potential window for the formation of a stable dual chiral-wave state as compared to the well known two flavor case. In addition, strangeness catalyzes the occurrence of a new branch of non-homogeneous solutions at moderate densities. This case study is addressed at zero temperature within the SU(3) flavor Nambu-Jona-Lasinio model with the 't Hooft determinantal flavor mixing interaction. The modulation of the chiral condensates in the light quark sector is taken to be one-dimensional, while strangeness is embedded as a homogeneous condensate in the spontaneously broken phase of chiral symmetry. A finite current quark mass for the strange quark is incorporated, while the up and down current masses are set to zero. In that case the modulation considered provides an exact analytic solution for the system. Despite the simplicity of the \textit{ansatz}, the emerging phase diagram displays a very rich structure.

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arXiv2013

Light-Front Quantum Chromodynamics: A framework for the analysis of hadron physics

An outstanding goal of physics is to find solutions that describe hadrons in the theory of strong interactions, Quantum Chromodynamics (QCD). For this goal, the light-front Hamiltonian formulation of QCD (LFQCD) is a complementary approach to the well-established lattice gauge method. LFQCD offers access to the hadrons' nonperturbative quark and gluon amplitudes, which are directly testable in experiments at existing and future facilities. We present an overview of the promises and challenges of LFQCD in the context of unsolved issues in QCD that require broadened and accelerated investigation. We identify specific goals of this approach and address its quantifiable uncertainties.

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arXiv2012

Radial and angular-momentum Regge trajectories: a systematic approach

We present the analysis of Ref.[1] of the radial (n) and angular-momentum (J) Regge trajectories for all light-quark meson states listed in the Particle Data Tables. The parameters of the trajectories are obtained with linear regression, with weight of each resonance inversely proportional to its half-width squared, (Γ/2)^2. The joint analysis in the (n,J,M^2) Regge plane indicates, at the 4.5 standard deviation level, that the slopes in n are larger from the slopes in J. Thus no strict universality of slopes occurs in the light non-strange meson sector. We also extend our analysis to the kaon sector.

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arXiv2009

Describing transverse dynamics and space-time evolution at RHIC in a hydrodynamic model with statistical hadronization

A hydrodynamic model coupled to the statistical hadronization code Therminator is used to study a set of observables in the soft sector at RHIC. A satisfactory description of the pT-spectra and elliptic flow is obtained, similarly to other hydrodynamic models. With the Gaussian initial conditions the transverse femtoscopic radii are also reproduced, providing a possible solution of the RHIC HBT puzzle.

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arXiv2009

Consistent hydrodynamic description of one- and two-particle observables in relativistic heavy-ion collisions at RHIC

We show that a consistent hydrodynamic description of soft-hadronic one- and two-particle observables (the HBT radii) studied in the relativistic heavy-ion collisions at RHIC may be obtained if one uses the Gaussian energy density profile as the initial condition. The transverse-momentum spectra, the elliptic flow coefficient $v_2$, and the pionic azimuthally sensitive HBT radii are successfully reproduced, which hints that the long standing HBT puzzle has been solved.

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arXiv2008

Solution of the RHIC HBT puzzle with Gaussian initial conditions

It is argued that the consistent description of the transverse-momentum spectra, elliptic flow, and the HBT radii in the relativistic heavy-ion collisions studied at RHIC may be obtained within the hydrodynamic model if one uses the Gaussian profile for the initial energy density in the transverse plane. Moreover, we show that the results obtained in the scenario with an early start of hydrodynamics (at the proper time tau0 = 0.25 fm) are practically equivalent to the results obtained in the model where the hydrodynamics is preceded by the free-streaming stage of partons (in the proper time interval 0.25 fm < tau < 1 fm) which suddenly equilibrate and with the help of the Landau matching conditions are transformed into the hydrodynamic regime (at the proper time tau0 = 1 fm).

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arXiv2008

Hydrodynamics and perfect fluids: uniform description of soft observables in Au+Au collisions at RHIC

It is argued that the use of the initial Gaussian energy density profile for hydrodynamics leads to much better uniform description of the RHIC heavy-ion data than the use of the standard initial condition obtained from the Glauber model. With the modified Gaussian initial conditions we successfully reproduce the transverse-momentum spectra, v2, and the pionic HBT radii (including their azimuthal dependence). The emerging consistent picture of hadron production hints that a solution of the long standing RHIC HBT puzzle has been found.

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arXiv2006

Pion correlations in hydro-inspired models with resonances

The effects of the freeze-out hypersurface and resonance decays on the pion correlation functions in relativistic heavy-ion collisions are studied with help of the hydro-inspired models with single freeze-out. The heavy-ion Monte-Carlo generator THERMINATOR is used to generate hadronic events describing production of particles from a thermalized and expanding source. We find that the short-lived resonances increase the pionic HBT radii by about 1 fm. We also find that the pion HBT data from RHIC are fully compatible with the single freeze-out scenario provided a special choice of the freeze-out hypersurface is made.

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arXiv2006

Photon distribution amplitudes and light-cone wave functions in chiral quark models

The leading- and higher-twist distribution amplitudes and light-cone wave functions of real and virtual photons are analyzed in chiral quark models. The calculations are performed in the nonlocal quark model based on the instanton picture of QCD vacuum, as well as in the spectral quark model and the Nambu--Jona-Lasinio model with the Pauli-Villars regulator, which both treat interaction of quarks with external fields locally. We find that in all considered models the leading-twist distribution amplitudes of the real photon defined at the quark-model momentum scale are constant or remarkably close to the constant in the $x$ variable, thus are far from the asymptotic limit form. The QCD evolution to higher momentum scales is necessary and we carry it out at the leading order of the perturbative theory for the leading-twist amplitudes. We provide estimates for the magnetic susceptibility of the quark condensate $χ_m$ and the coupling $f_{3γ}$, which in the nonlocal model turn out to be close to the estimates from QCD sum rules. We find the higher-twist distribution amplitudes at the quark model scale and compare them to the Wandzura-Wilczek estimates. In addition, in the spectral model we evaluate the distribution amplitudes and light-cone wave functions of the $ρ$-meson.

hep-ph↗
arXiv2005

Event-by-event pT fluctuations and multiparticle clusters in relativistic heavy-ion collisions

We explore the dependence of the pT correlations in the event-by-event analysis of relativistic heavy-ion collisions at RHIC made recently by the PHENIX and STAR Collaborations. We point out that the observed scaling of strength of dynamical fluctuations with the inverse number of particles can be naturally explained by the formation of clusters. We argue that the large magnitude of the measured covariance implies that the clusters contain at least several particles. We also discuss whether the clusters may originate from jets. In addition, we provide numerical estimates of correlations coming from resonance decays and thermal clusters.

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arXiv2004

Strange particle production in a single-freeze-out model

The transverse-momentum spectra and elliptic flow of strange particles are calculated in the framework of the single-freeze-out model and compared with the recent RHIC data. An overall very good agreement between the model predictions and the data is obtained.

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arXiv2004

Low Energy Chiral Lagrangian in Curved Space-Time from the Spectral Quark Model

We analyze the recently proposed Spectral Quark Model in the light of Chiral Perturbation Theory in curved space-time. In particular, we calculate the chiral coefficients $L_1, ..., L_{10}$, as well as the coefficients $L_{11}$, $L_{12}$, and $L_{13}$, appearing when the model is coupled to gravity. The analysis is carried for the SU(3) case. We analyze the pattern of chiral symmetry breaking as well as elaborate on the fulfillment of anomalies. Matching the model results to resonance meson exchange yields the relation between the masses of the scalar, tensor and vector mesons, $M_{f_0}=M_{f_2}=\sqrt{2} M_V= 4 \sqrt{3 /N_c} πf_π$. Finally, the large-$N_c$ limit suggests the dual relations in the vector and scalar channels, $M_V=M_S= 2 \sqrt{6 /N_c} πf_π$ and $ ^{1/2}_S = < r^2 >^{1/2}_V = 2 \sqrt{N_c} / f_π= 0.59 {\rm fm} $.

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