Nuclear Theory·nucl-th

Wednesday·May 31, 2023

7 papers—2 primary·5 cross-listed

01
A study of medium effects in elastic $π N$ and $π A$ scatterings
Hyeon-dong Han🇰🇷
The elastic $π N$ scattering is investigated for the $I = 3/2$ channel dominated by the $Δ (1232)$ resonance at finite baryon density, employing the effective Lagrangian approach at the tree-level Born approximation. The quark-meson coupling (QMC) model is employed to describe the in-medium baryon properties that are constructed at the quark level, such as the nucleon and $Δ$ masses, and $Δ$ full decay width. I reproduce the experimental data of the cross-section in a vacuum as a justification of our approach and then analyze the in-medium total and differential cross-sections as well as proton-spin asymmetry. Following the results of the in-medium elastic $π N$ scattering calculation, the elastic $π A$ scattering is investigated at finite baryon density in the framework of the Eikonal Glauber model for the light nuclei, $^{4} He$ and $^{12} C$ . For the description of the finite nuclei, the Wood-Saxon density profile, and an expansion of the charge distribution as a sum of Gaussians are employed in this study. The nuclear density distribution $ρ_{A}$ , effective baryon mass $m_{B}^{*}$ , in-medium decay width $Γ_{Δ}^{*}$ , and in-medium coupling constants $f_{π N N}^{*}$ and $f_{π N Δ}^{*}$ are analyzed as well as the total cross-section. The results show that the effective baryon mass and cross-sections in the medium decrease as density increases except for the $Δ$ decay width, which increases as the density increases. The elastic $π A$ scattering at the tree-level Born approximation reproduces well the experimental data for $^{4} He$ but overestimates for $^{12} C$ . Results for the in-medium $Δ$ resonance and other findings in this work will be relevant for the relativistic heavy-ion collision experiments.
nucl-thhep-phnucl-ex0 citations
02
Effects of multiple single-particle basis states in scattering systems
Curtis D. Abell🇦🇺 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇨🇳
Low-lying baryon resonances have been explored using Hamiltonian Effective Field Theory (HEFT), in a formalism where resonances with a three-quark component are described by both two-particle meson-baryon states and a bare basis state. Here, we investigate the use of multiple bare states in the Hamiltonian, to extend the formalism to higher energy ranges, and represent a larger portion of the low-lying baryon spectrum. Introducing a second bare state into a toy model extension of the low-energy $Δ (1232)$ system, we explore the influence of the second bare state on the position of poles in the infinite-volume $T$ -matrix. Considering the same system in a finite-volume, we analyse the finite-volume energy spectrum in the presence of a second bare state, providing insight into the interplay between two bare basis states, representing quark-model states, and the relationship between infinite-volume poles and finite-volume eigenstates.
nucl-thhep-lathep-phAnnals Phys.(2023)·12 citations
03
Fate of the topological susceptibility in two-color dense QCD
Mamiya Kawaguchi🇨🇳 · Daiki Suenaga🇯🇵
We explore the topological susceptibility at finite quark chemical potential and zero temperature in two-color QCD (QC $_{2}$ D) with two flavors. Through the Ward-Takahashi identities of QC $_{2}$ D, we find that the topological susceptibility in the vacuum solely depends on three observables: the pion decay constant, the pion mass, and the $η$ mass in the low-energy regime of QC $_{2}$ D. Based on the identities, we numerically evaluate the topological susceptibility at finite quark chemical potential using the linear sigma model with the approximate Pauli-Gursey $S U (4)$ symmetry. Our findings indicate that, in the absence of $U (1)_{A}$ anomaly effects represented by the Kobayashi-Maskawa-'t Hooft-type determinant interaction, the topological susceptibility vanishes in both the hadronic and baryon superfluid phases. On the other hand, when the $U (1)_{A}$ anomaly effects are present, the constant and nonzero topological susceptibility is induced in the hadronic phase, reflecting the mass difference between the pion and $η$ meson. Meanwhile, in the superfluid phase it begins to decrease smoothly. The asymptotic behavior of the decrement is fitted by the continuous reduction of the chiral condensate in dense QC $_{2}$ D, which is similar to the behavior observed in hot three-color QCD matter. In addition, effects from the finite diquark source on the topological susceptibility are discussed. We expect that the present study provides a clue to shed light on the role of the $U (1)_{A}$ anomaly in cold and dense QCD matter.
↳ hep-phhep-latnucl-thJHEP(2023)·18 citations
04
Numerical indication that center vortices drive dynamical mass generation in QCD
Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺 · Adam Virgili🇦🇺
The first calculation of the response of the momentum space quark propagator to center vortices in the ground state fields of QCD is presented. Center vortices are identified on 2+1-flavour dynamical gauge fields with $m_{π} ≃ 156$ MeV to obtain the vortex-removed and vortex-only quark propagator. Dynamical mass generation is found to vanish upon vortex removal, while the vortex-only field is able to generate dynamical mass. These new signatures strengthen the lattice QCD evidence indicating that center vortices underpin both dynamical chiral symmetry breaking and quark confinement.
↳ hep-lathep-phhep-thnucl-thPRD(2024)·12 citations
05
Forward-backward correlations with the $Σ$ quantity in the wounded constituent framework at LHC energies
Iwona Anna Sputowska🇵🇱
$Σ$ is a new correlation measure, quite recently introduced to heavy-ion physics. This measure, defined in the independent source model as a strongly intensive quantity, is expected to be free of the effects of system volume and volume fluctuations. This paper discusses the forward-backward correlation quantified with the $Σ$ observable calculated in the framework of the wounded nucleon model (WNM) and wounded quark model (WQM). Findings show that the wounded constituent approach outperforms the commonly used heavy-ion Monte Carlo generators, such as HIJING, AMPT or EPOS, by accurately describing the experimental data on FB correlations with $Σ$ measured by ALICE in Xe--Xe reactions at $s_{NN}$ =5.44 TeV and in Pb--Pb collisions at $s_{NN}$ = 2.76 and 5.02 TeV. This paper demonstrates that $Σ$ can be a unique tool for determining the fragmentation function of a wounded constituent in a symmetric nucleus-nucleus collision. However, in the wounded constituent framework, it is no longer a strongly intensive quantity.
↳ hep-phhep-exnucl-exnucl-thPRC(2023)·3 citations
06
Unified triquark equations
A. N. Kvinikhidze🇬🇪 · B. Blankleider🇦🇺
We derive covariant equations describing the three-quark bound state in terms of quark and diquark degrees of freedom. The equations are exact in the approximation where three-body forces are neglected. A feature of these equations is that they unify two often-used but seemingly unrelated approaches that model baryons as quark-diquark systems; namely, (i) the approach using Poincaré covariant quark+diquark Faddeev equations driven by a one-quark-exchange kernel [pioneered by Cahill {\it et al.}, Austral.\ J.\ Phys.\ {\bf 42}, 129 (1989) and Reinhardt, Phys.\ Lett.\ B {\bf 244}, 316 (1990)], and (ii) the approach using the quasipotential quark-diquark bound-state equation where the kernel consists of the lowest-order contribution from an underlying quark-quark potential [pioneered by Ebert {\it et al.}, Z.\ Phys.\ C {\bf 76} 111 (1997)]. In particular, we show that each of these approaches corresponds to the unified equations with its kernel taken in different, non-overlapping, approximations.
↳ hep-phnucl-thPRD(2023)·1 citation
07
$P_{c}$ states and their open-charm decays with the complex scaling method
Zi-Yang Lin🇨🇳 · Jian-Bo Cheng🇨🇳 · Bo-Lin Huang🇨🇳 · Shi-Lin Zhu🇨🇳
A partial width formula is proposed using the analytical extension of the wave function in momentum space. The distinction of the Riemann sheets is explained from the perspective of the Schrodinger equation. The analytical form in coordinate space and the partial width are derived subsequently. Then a coupled-channel analysis is performed to investigate the open-charm branching ratios of the $P_{c}$ states, involving the contact interactions and one-pion-exchange potential with the three-body effects. The low energy constants are fitted using the experimental masses and widths as input. The $P_{c} (4312)$ is found to decay mainly to $Λ_{c} D ˉ^{*}$ , while the branching ratios of the $P_{c} (4440)$ and $P_{c} (4457)$ in different channels are comparable. Under the reasonable assumption that the off-diagonal contact interactions are small, the $J^{P}$ quantum numbers of the $P_{c} (4440)$ and the $P_{c} (4457)$ prefer $\frac{1}{2}^{-}$ and $\frac{3}{2}^{-}$ respectively. Three additional $P_{c}$ states at 4380 MeV, 4504 MeV and 4516 MeV, together with their branching ratios, are predicted. A deduction of the revised one-pion-exchange potential involving the on-shell three-body intermediate states is performed.
↳ hep-phhep-exhep-latnucl-thPRD(2023)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE

A study of medium effects in elastic πN and πA scatterings

Effects of multiple single-particle basis states in scattering systems

Fate of the topological susceptibility in two-color dense QCD

Numerical indication that center vortices drive dynamical mass generation in QCD

Forward-backward correlations with the Σ quantity in the wounded constituent framework at LHC energies

Unified triquark equations

Pc​ states and their open-charm decays with the complex scaling method

Affiliations

A study of medium effects in elastic $π N$ and $π A$ scatterings

Forward-backward correlations with the $Σ$ quantity in the wounded constituent framework at LHC energies

$P_{c}$ states and their open-charm decays with the complex scaling method