Nuclear Theory·nucl-th

Wednesday·January 3, 2024

6 papers—4 primary·2 cross-listed

01
Exploring the partonic collectivity in small systems at the LHC
Yuanyuan Wang · Wenbin Zhao · Huichao Song
Using the Hydro-Coal-Frag model that combines hydrodynamics at low $p_{T}$ , quark coalescence at intermediate $p_{T}$ , and the LBT transport model at high $p_{T}$ , we study the spectra and elliptic flow of identified hadrons in high multiplicity p--Pb and p--p collisions at the Large Hadron Collider (LHC). In p--Pb collisions, the Hydro-Coal-Frag model gives a good description of the differential elliptic flow over the $p_{T}$ range from 0 to 6 GeV and the approximate number of constituent quark (NCQ) scaling at intermediate $p_{T}$ . Although Hydro-Coal-Frag model can also roughly describe the elliptic flow in high multiplicity p--p collisions with the quark coalescence process, the larger contribution from the string fragmentations leads to a notable violation of the NCQ scaling of $v_{2}$ at intermediate $p_{T}$ as observed in the experiment. Comparison runs of the Hydro-Frag model without the coalescence process demonstrate that regardless the parameter adjustments, the Hydro-Frag model cannot simultaneously describe the $p_{T}$ spectra and the elliptic flow of identified hadrons in either p--Pb collisions or p--p collisions. The calculations in this paper thus provide support for the existence of partonic degrees of freedom and the possible formation of the QGP in the small systems created at the LHC.
nucl-thhep-phnucl-exPRC(2026)·12 citations
02
Symmetry-projected variational calculations with the numerical suite TAURUS II. Configuration mixing of symmetry-projected reference states
Benjamin Bally🇫🇷 · Tomás R. Rodríguez🇪🇸
We present the numerical codes TAURUS_pav and TAURUS_mix that, combined, perform the configuration mixing of symmetry-projected real general Bogoliubov quasiparticle states represented in a spherical harmonic oscillator basis. The model space considered is invariant under spatial and isospin rotations but no specific set of orbits is assumed such that the codes can carry out both valence-space and no-core calculations. In addition, no number parity is assumed for the Bogoliubov quasiparticle states such that the codes can be used to describe even-even, odd-even and odd-odd nuclei. To demonstrate the potential of the codes, we perform an example no-core calculation of $^{24}$ Mg using a modern microscopic interaction.
nucl-thEPJA(2024)·11 citations
03
The reaction $π N \to ω N$ in a dynamical coupled-channel approach
Yu-Fei Wang🇩🇪
This talk is on a refined investigation on light flavor meson-baryon scatterings, using a dynamical coupled-channel approach, i.e. the Jülich-Bonn model. The previous channel space of $π N$ , $π Δ$ , $σ N$ , $ρN$ , $η N$ , $K Λ$ and $K Σ$ is extended by adding the $ω N$ final state. The spectra of $N^{*}$ and $Δ$ resonances are extracted, based on the result of a global fit to a worldwide collection of data, in the energy region from the $π N$ threshold to center-of-mass energy $z = 2.3$ GeV (approximately $300$ parameters against $9000$ data points). A negative value of the $ω N$ elastic spin-averaged scattering length has been extracted.
nucl-thhep-phnucl-exphysics.comp-phEPJ Web Conf.(2024)·3 citations
04
On the nature of the $N^{*}$ and $Δ$ resonances via coupled-channel dynamics
Yu-Fei Wang🇩🇪
This talk focuses on a recent work aiming at determining the composition of certain $N^{*}$ and $Δ$ resonances, i.e. whether they are compact states formed directly by quarks and gluons, or composite generated from the meson-baryon interaction. The information of the resonance poles is provided by a comprehensive coupled-channel approach, the Jülich-Bonn model. Thirteen states that are significant in this approach are studied. Two criteria for each state are adopted in this paper, the comparison thereof roughly indicates the model uncertainties. It is found that the conclusions for eight resonances are relatively certain: $N (1535) \frac{1}{2}^{-}$ , $N (1440) \frac{1}{2}^{+}$ , $N (1710) \frac{1}{2}^{+}$ , and $N (1520) \frac{3}{2}^{-}$ tend to be composite; whereas $N (1650) \frac{1}{2}^{-}$ , $N (1900) \frac{3}{2}^{+}$ , $N (1680) \frac{5}{2}^{+}$ , and $Δ (1600) \frac{3}{2}^{+}$ tend to be compact.
nucl-thhep-phEPJ Web Conf.(2024)·1 citation
05
A Collinear Perspective on the Regge Limit
Anjie Gao🇺🇸 · Ian Moult🇺🇸 · Sanjay Raman🇺🇸 · Gregory Ridgway🇺🇸 · Iain W. Stewart🇺🇸
The high energy (Regge) limit provides a playground for understanding all loop structures of scattering amplitudes, and plays an important role in the description of many phenomenologically relevant cross-sections. While well understood in the planar limit, the structure of non-planar corrections introduces many fascinating complexities, for which a general organizing principle is still lacking. We study the structure of multi-reggeon exchanges in the context of the effective field theory for forward scattering, and derive their factorization into collinear operators (impact factors) and soft operators. We derive the structure of the renormalization group consistency equations in the effective theory, showing how the anomalous dimensions of the soft operators are related to those of the collinear operators, allowing us to derive renormalization group equations in the Regge limit purely from a collinear perspective. The rigidity of the consistency equations provides considerable insight into the all orders organization of Regge amplitudes in the effective theory, as well as its relation to other approaches. Along the way we derive a number of technical results that improve the understanding of the effective theory. We illustrate this collinear perspective by re-deriving all the standard BFKL equations for two-Glauber exchange from purely collinear calculations, and we show that this perspective provides a number of conceptual and computational advantages as compared to the standard view from soft or Glauber physics. We anticipate that this formulation in terms of collinear operators will enable a better understanding of the relation between BFKL and DGLAP in gauge theories, and facilitate the analysis of renormalization group evolution equations describing Reggeization beyond next-to-leading order.
↳ hep-phhep-thnucl-thJHEP(2024)·23 citations
06
Femtoscopy with Lévy sources from SPS through RHIC to LHC
Máté Csanád🇭🇺 · Dániel Kincses🇭🇺
Femtoscopy is a unique tool to investigate the space-time geometry of the matter created in ultra-relativistic collisions. If the probability density distribution of hadron emission is parametrized, then the dependence of its parameters on particle momentum, collision energy, and collision geometry can be given. In recent years, several measurements came to light that indicated the adequacy of assuming a Lévy-stable shape for the mentioned distribution. In parallel, several new phenomenological developments appeared, aiding the interpretation of the experimental results or providing tools for the measurements. In this paper, we discuss important aspects of femtoscopy with Lévy sources in light of some of these advances, including phenomenological and experimental ones.
↳ hep-phnucl-thUniverse(2024)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE

Exploring the partonic collectivity in small systems at the LHC

Symmetry-projected variational calculations with the numerical suite TAURUS II. Configuration mixing of symmetry-projected reference states

The reaction πN→ωN in a dynamical coupled-channel approach

On the nature of the N∗ and Δ resonances via coupled-channel dynamics

A Collinear Perspective on the Regge Limit

Femtoscopy with Lévy sources from SPS through RHIC to LHC

Affiliations

The reaction $π N \to ω N$ in a dynamical coupled-channel approach

On the nature of the $N^{*}$ and $Δ$ resonances via coupled-channel dynamics