Nuclear Theory·nucl-th

Friday·May 31, 2019

9 papers—5 primary·4 cross-listed

06
[Submitted on 29 May 2019] (cross-list from hep-ph)
Extensive/nonextensive statistics for $p_{T}$ distributions of various charged particles produced in p+p and A+A collisions in a wide range of energies
Abdel Nasser Tawfik (Nile U., ECTP and Johann Wolfgang Goethe-Universitat)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo)🇪🇬
We present a systematic study for the statistical fits of the transverse momentum distributions of charged pions, Kaons and protons produced at energies ranging between 7.7 and 2670 GeV to the extensive Boltzmann-Gibbs (BG) and the nonextensive statistics (Tsallis as a special type and the generic axiomatic nonextensive approach). We also present a comprehensive review on various experimental parametrizations proposed to fit the transverse momentum distributions of these produced particles. The inconsistency that the BG approach is to be utilized in characterizing the chemical freezeout, while the Tsallis approach in determining the kinetic freezeout is elaborated. The resulting energy dependence of the different fit parameters largely varies with the particle species and the degree of (non)extensivity. This manifests that the Tsallis nonextensive approach seems to work well for p+p rather than for A+A collisions. Drawing a complete picture of the utilization of Tsallis statistics in modeling the transverse momentum distributions of several charged particle produced at a wide range of energies and accordingly either disprove or though confirm the relevant works are main advantages of this review. We propose analytical expressions for the dependence of the fit parameters obtained on the size of the colliding system, the energy, as well as the types of the statistical approach applied. We conclude that the statistical dependence of the various fit parameters, especially between Boltzmann and Tsallis approaches could be understood that the statistical analysis ad hoc is biased to the corresponding degree of extensivity (Boltzmann) or nonextensivity (Tsallis). Alternatively, the empirical parameterizations, the other models, and the generic (non)extensive approach seem to relax this biasness.
Comments:
42 pages, 17 figures, IX tables, submitted to JSTAT
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.12756 [pdf]
Ukr.J.Phys.(2022)·15 citations
07
[Submitted on 29 May 2019] (cross-list from hep-ph)
Almost-Entirely Empirical Estimation for Chemical Potential
Abdel Nasser Tawfik (Nile U., ECTP and Johann Wolfgang Goethe-Universitat)🇩🇪 · Magda Abdel Wahab🇪🇬 · Hayam Yassin (Ain Shams U., Cairo)🇪🇬 · Hadeer Nasr El Din (Modern Academy for Engineering, Cairo)🇪🇬
Based on statistical thermal approaches, the transverse momentum distribution of the well-identified produced particles, $π^{+}$ , $π^{-}$ , $K^{+}$ , $K^{-}$ , $p$ , $p ˉ$ , is studied. From the partition function of grand-canonical ensemble, we propose a generic expression for the dependence of the full chemical potential $μ$ on rapidity $y$ . Then, by fitting this expression with the experimental results of most central $p_{⊥}$ and $d^{2} N /2 π p_{⊥} d p_{⊥} d y$ , at $7.7$ , $11.5$ , $19.6$ , $27$ , $39$ , $130$ , $200$ GeV, we introduce a generic expression for the rapidity dependence of $μ$ , at different energies and particle types, $μ = a + b y^{2}$ . The resulting energy dependence reads $s_{NN} = c [(μ - a) / b]^{d /2}$ . As a validation check, the proposed approach reproduces, excellently, the rapidity spectra measured at different energies.
Comments:
11 pages, 5 figures, VI tables, submitted to JETP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.12758 [pdf]
J.Exp.Theor.Phys.(2020)·3 citations
08
[Submitted on 30 May 2019] (cross-list from hep-th)
Analytic crystals of solitons in the four dimensional gauged non-linear sigma model
Fabrizio Canfora🇨🇱 · Seung Hun Oh🇰🇷 · Aldo Vera🇨🇱
The first analytic topologically non-trivial solutions in the (3+1)-dimensional gauged non-linear sigma model representing multi-solitons at finite volume with manifest ordered structures generating their own electromagnetic field are presented. The complete set of seven coupled non-linear field equations of the gauged non-linear sigma model together with the corresponding Maxwell equations are reduced in a self-consistent way to just one linear Schrodinger-like equation in two dimensions. The corresponding two dimensional periodic potential can be computed explicitly in terms of the solitons profile. The present construction keeps alive the topological charge of the gauged solitons. Both the energy density and the topological charge density are periodic and the positions of their peaks show a crystalline order. These solitons describe configurations in which (most of) the topological charge and total energy are concentrated within three-dimensional tube-shaped regions. The electric and magnetic fields vanish in the center of the tubes and take their maximum values on their surface while the electromagnetic current is contained within these tube-shaped regions. Electromagnetic perturbations of these families of gauged solitons are shortly discussed.
Comments:
18 pages, 22 figures, accepted for publication on EUROPEAN PHYSICAL JOURNAL C
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.12818 [pdf]
EPJC(2019)·37 citations
09
[Submitted on 30 May 2019] (cross-list from hep-ph)
Dispersion relations for $γ^{*} γ^{*} \to π π$ : helicity amplitudes, subtractions, and anomalous thresholds
Martin Hoferichter🇺🇸 · Peter Stoffer🇺🇸
We present a comprehensive analysis of the dispersion relations for the doubly-virtual process $γ^{*} γ^{*} \to π π$ . Starting from the Bardeen-Tung-Tarrach amplitudes, we first derive the kernel functions that define the system of Roy-Steiner equations for the partial-wave helicity amplitudes. We then formulate the solution of these partial-wave dispersion relations in terms of Omnès functions, with special attention paid to the role of subtraction constants as critical for the application to hadronic light-by-light scattering. In particular, we explain for the first time why for some amplitudes the standard Muskhelishvili-Omnès solution applies, while for others a modified approach based on their left-hand cut is required unless subtractions are introduced. In the doubly-virtual case, the analytic structure of the vector-resonance partial waves then gives rise to anomalous thresholds, even for space-like virtualities. We develop a strategy to account for these effects in the numerical solution, illustrated in terms of the $D$ -waves in $γ^{*} γ^{*} \to π π$ , which allows us to predict the doubly-virtual responses of the $f_{2} (1270)$ resonance. In general, our results form the basis for the incorporation of two-meson intermediate states into hadronic light-by-light scattering beyond the $S$ -wave contribution.
Comments:
32 pages, 5 figures; version published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1905.13198 [pdf]
JHEP(2019)·88 citations

Affiliations

first authorsco-authorsvia INSPIRE

Extensive/nonextensive statistics for pT​ distributions of various charged particles produced in p+p and A+A collisions in a wide range of energies

Almost-Entirely Empirical Estimation for Chemical Potential

Analytic crystals of solitons in the four dimensional gauged non-linear sigma model

Dispersion relations for γ∗γ∗→ππ: helicity amplitudes, subtractions, and anomalous thresholds

Affiliations

Extensive/nonextensive statistics for $p_{T}$ distributions of various charged particles produced in p+p and A+A collisions in a wide range of energies

Dispersion relations for $γ^{} γ^{} \to π π$ : helicity amplitudes, subtractions, and anomalous thresholds