Nuclear Theory·nucl-th

Thursday·May 18, 2023

11 papers—5 primary·6 cross-listed

06
The deuteron charge radıus $r_{c}$ in the framework of the hard-wall AdS/QCD model
Shahin Mamedov🇦🇿 · Narmin Akbarova🇦🇿 · Minaya Allahverdiyeva🇦🇿
We study the deuteron charge radius in the framework of a hard-wall AdS/QCD model. We present basic elements of the hard-wall model and write metrics for the AdS space. We introduce a vector field with twist $τ = 6$ describing deuteron in the bulk of AdS space and other vector fields to describe photon respectively, write an effective action for the bulk fields interactions, find a $G_{1} (Q^{2})$ , $G_{2} (Q^{2})$ and $G_{3} (Q^{2})$ form factors, then quadrupole $G_{Q} (Q^{2})$ and charge $G_{C} (Q^{2})$ form-factors of a deuteron. Thus, from the charge $G_{C} (Q^{2})$ form factor we find the deuteron charge radius $R_{C}$ in the framework of a hard-wall AdS/QCD model. Then we compare our result with the results soft-wall model and experimental data.
↳ hep-phnucl-thPhys.Part.Nucl.Lett.(2023)·1 citation
07
Towards Double Parton Distributions from First Principles using Large Momentum Effective Theory
Max Jaarsma🇳🇱 · Rudi Rahn🇳🇱 · Wouter J. Waalewijn🇳🇱
In double parton scattering (DPS), two partonic collisions take place between one pair of colliding hadrons. The effect of DPS can be significant for precision measurements due to the additional radiation from secondary partonic collisions, and especially for specific processes such as same-sign WW production. Its effect is usually included through Monte Carlo parton showers. In a factorization approach to DPS, the initial state is described by double parton distributions (DPDs). These are currently poorly constrained by experiment, but provide a view on interesting correlations between partons in the hadron. Here we show that the Large Momentum Effective Theory approach can be applied to DPDs. Specifically, we present a general matching relation between DPDs and lattice-calculable quasi-DPDs for general flavor, spin and color structures. We furthermore calculate the one-loop matching coefficients for the quark-quark DPDs, verifying that the infrared logarithms and divergences cancel in the matching. While we restrict to the flavor-non-singlet case, we do take color and spin correlations into account. Interestingly, quasi-DPDs combines nontrivial features from both the collinear and transverse momentum dependent quasi-parton distribution functions. This represents a first step in extending the quasi-PDF approach to DPDs, opening up a new way to constrain these distributions using lattice QCD.
↳ hep-phhep-latnucl-thJHEP(2023)·20 citations
08
The non-relativistic limit of first-order relativistic viscous fluids
Abhishek Hegade K R · Justin L. Ripley · Nicolás Yunes
Out-of-equilibrium effects may play an important role in the dynamics of neutron star mergers and in heavy-ion collisions. Bemfica, Disconzi, Noronha and Kovtun (BDNK) recently derived a causal, locally well-posed, and modally stable relativistic fluid model that incorporates the effects of viscosity and heat diffusion. We study the non-relativistic limit of this fluid model and show that causality for relativistic motion restricts the transport coefficients in the non-relativistic limit. This restriction provides an upper bound on the ratio of the shear viscosity to the entropy density for fluids that can be described as relativistic within the BDNK model and can be exactly modeled using the Navier-Stokes equation in the non-relativistic limit. Furthermore, we show that the Fourier law of heat conduction must be modified by higher gradient corrections for such fluids. We also show that the non-relativistic limit of the BDNK equations of motion are never hyperbolic, in contrast to the non-relativistic limit of extended variable models, whose non-relativistic equations of motion can be hyperbolic or not depending on the scaling of the transport coefficients present in the auxiliary equations for viscous degrees of freedom.
↳ gr-qchep-thmath-phmath.MP+1PRD(2023)·11 citations
09
Axial anomaly effect to the chiral-partner structure of diquarks at high temperature
Daiki Suenaga🇯🇵 · Makoto Oka🇯🇵
Masses of positive-parity and negative-parity diquarks are investigated at finite temperature with a quark chemical potential. We employ the three-flavor Nambu-Jona-Lasinio model, in order to delineate chiral properties of the diquarks, in particular, the mass degeneracy of chiral partners under extreme conditions. We focus on the effects of $U (1)_{A}$ axial anomaly on manifestation of the chiral-partner structures. We find that, in the absence of anomaly effects to the diquarks, the mass degeneracies in all $[u d]$ , $[s u]$ and $[s d]$ diquark sectors take place prominently above the pseudocritical temperature of the chiral restoration. On the other hand, the anomaly effects are found to hinder the $[u d]$ diquark from exhibiting the mass degeneracy, accompanied by a slow reduction of the $s ˉ s$ condensate, while the $[s u]$ and $[s d]$ diquarks are not much affected. Our present investigation will provide useful information on the chiral-partner structure with the anomaly effects of diquarks for heavy-ion collision experiments of singly heavy baryons and doubly heavy tetraquarks, and for future lattice simulations of the diquarks.
↳ hep-phnucl-thPRD(2023)·11 citations
10
$Δ$ -baryon axialvector and pseudoscalar form factors, and associated PCAC relations
Pei-Lin Yin🇨🇳 · Chen Chen🇨🇳 · Christian S. Fischer🇩🇪 · Craig D. Roberts🇨🇳
A quark+diquark Faddeev equation treatment of the baryon bound state problem in Poincaré-invariant quantum field theory is used to deliver parameter-free predictions for all six $Δ$ -baryon elastic weak form factors. Amongst the results, it is worth highlighting that there are two distinct classes of such $Δ$ -baryon form factors, $(g_{1}, g_{3}, G_{π ΔΔ})$ , $(h_{1}, h_{3}, H_{π ΔΔ})$ , the functions within each of which are separately linked via partial conservation of axial current (PCAC) and Goldberger-Treiman (GT) relations. Respectively within each class, the listed form factors possess qualitatively the same structural features as the nucleon axial, induced pseudoscalar, and pion-nucleon coupling form factors. For instance, the $Δ$ -baryon $g_{1}$ axial form factor can reliably be approximated by a dipole function, characterised by an axial charge $g_{A}^{Δ^{+}} = 0.71 (9)$ and mass-scale $m_{A}^{Δ} = 0.95 (2) m_{Δ}$ . Moreover, the two distinct $Δ$ -baryon PCAC form factor relations are satisfied to a high degree of accuracy on a large range of $Q^{2}$ ; the associated GT relations present good approximations only on $Q^{2} / m_{Δ}^{2} ≃ 0$ ; and pion pole dominance approximations are reliable within both classes. There are two $π ΔΔ$ couplings: $g_{π ΔΔ} = 10.46 (1.88)$ ; $h_{π ΔΔ} = 35.73 (3.75)$ ; and the associated form factors are soft. Such couplings commonly arise in phenomenology, which may therefore benefit from our analyses. A flavour decomposition of the axial charges reveals that quarks carry $71$ \% of the $Δ$ -baryon spin. The analogous result for the proton is $\approx 65$ \%.
↳ hep-phhep-exhep-latnucl-ex+1EPJA(2023)·8 citations
11
Chemical potential of a hadronic fireball in the freeze-out stage
Yaroslav D. Krivenko-Emetov🇦🇹 · Andriy I. Smetana🇦🇹
This article explores the van der Waals gas model proposed to describe the hadronic stages of nuclear fireball evolution during the cooling stage. Two different models were proposed for the early and late stages of hadronization. At the initial stage, a two-component meson model consisting of $π^{0}$ and $π^{+}$ mesons was suggested, and at the later stage, a two-component nucleon model consisting of protons and neutrons was proposed. The interaction potential for both models was represented by a rectangular well, and the statistical sum was calculated using the saddle-point method. The analytic expressions for pressure and chemical potentials obtained from the model were compared with the corresponding numerical results of other authors obtained earlier using quantum chromodynamics (QCD) methods. The possibility of applying and using the effective chemical potential is also analyzed.
↳ hep-phnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE

The deuteron charge radıus rc​ in the framework of the hard-wall AdS/QCD model

Towards Double Parton Distributions from First Principles using Large Momentum Effective Theory

The non-relativistic limit of first-order relativistic viscous fluids

Axial anomaly effect to the chiral-partner structure of diquarks at high temperature

Δ-baryon axialvector and pseudoscalar form factors, and associated PCAC relations

Chemical potential of a hadronic fireball in the freeze-out stage

Affiliations

The deuteron charge radıus $r_{c}$ in the framework of the hard-wall AdS/QCD model

$Δ$ -baryon axialvector and pseudoscalar form factors, and associated PCAC relations