Nuclear Theory·nucl-th

Wednesday·September 21, 2022

9 papers—3 primary·6 cross-listed

04
[Submitted on 19 Sept 2022] (cross-list from gr-qc)
Causal, stable first-order viscous relativistic hydrodynamics with ideal gas microphysics
Alex Pandya · Elias R. Most · Frans Pretorius
We present the first numerical analysis of causal, stable first-order relativistic hydrodynamics with ideal gas microphysics, based in the formalism developed by Bemfica, Disconzi, Noronha, and Kovtun (BDNK theory). The BDNK approach provides definitions for the conserved stress-energy tensor and baryon current, and rigorously proves causality, local well-posedness, strong hyperbolicity, and linear stability (about equilibrium) for the equations of motion, subject to a set of coupled nonlinear inequalities involving the undetermined model coefficients (the choice for which defines the "hydrodynamic frame"). We present a class of hydrodynamic frames derived from the relativistic ideal gas "gamma-law" equation of state which satisfy the BDNK constraints, and explore the properties of the resulting model for a series of (0+1)D and (1+1)D tests in 4D Minkowski spacetime. These tests include a comparison of the dissipation mechanisms in Eckart, BDNK, and Muller-Israel-Stewart theories, as well as investigations of the impact of hydrodynamic frame on the causality and stability properties of Bjorken flow, planar shockwave, and heat flow solutions.
Comments:
22 pages, 7 figures, updated to match published version (PRD)
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2209.09265 [pdf]
PRD(2022)·38 citations
05
[Submitted on 19 Sept 2022] (cross-list from hep-ph)
$D^{*}$ and $D_{s}^{*}$ distribution amplitudes from Bethe-Salpeter wave functions
Fernando E. Serna🇧🇷 · Roberto Correa da Silveira🇧🇷 · Bruno El-Bennich🇧🇷
We report on the first calculation of the longitudinal and transverse light front distribution amplitudes of the $D^{*}$ and $D_{s}^{*}$ mesons and their first four moments. As a byproduct, we also obtain these distribution amplitudes for the $ρ$ , $ϕ$ , $K^{*}$ and $J /Ψ$ mesons and confirm a prediction of lattice QCD for the vector kaon: while the longitudinal distribution amplitude is almost symmetric, the transverse one is oblique implying that the strange quark carries more momentum.
Comments:
7 pages, 4 figures, 3 tables, published in Physical Review D Letters with slight text modifications and one more reference
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2209.09278 [pdf]
PRD(2022)·16 citations
06
[Submitted on 19 Sept 2022] (cross-list from hep-lat)
Large-Momentum Effective Theory vs. Short-Distance Operator Expansion: Contrast and Complementarity
Xiangdong Ji🇺🇸
Although equivalent in the infinite-momentum limit, large-momentum effective theory (LaMET) and short-distance operator product expansion (SD-OPE) are two different approaches to extract parton distribution functions (PDFs) from coordinate-space correlation functions in large-momentum hadrons. LaMET implements a momentum-space expansion in $Λ_{QCD} / [x (1 - x) P^{z}]$ to directly calculate PDFs $f (x)$ in a middle region of Bjorken $x \in [x_{min} \sim Λ_{QCD} / P^{z}, x_{max} \sim 1 - x_{m i n}]$ . SD-OPE applies perturbative QCD at small Euclidean distances $z$ to extract a range $[0, λ_{max}]$ of leading-twist correlations, $h (λ = z P^{z})$ , corresponding to the Fourier transformation of PDFs. Similar to the quantum mechanical uncertainty principle, an incomplete leading-twist correlation cannot be readily converted to a momentum-space local distribution, and the methods to solve the ``inverse problem'' involve essentially modelling of the missing information beyond $λ_{max}$ . On the other hand, short-distance correlations, along with the expected end-point asymptotics, can be used to phenomenologically fit the PDFs in the LaMET-complementary regions: $x \in [0, x_{min}]$ and $[x_{max}, 1]$ . We use the recent results of the pion valence quark distribution from the ANL/BNL collaboration to demonstrate this point.
Comments:
10 pages, 5 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.09332 [pdf]
Research(2025)·35 citations
07
[Submitted on 20 Sept 2022] (cross-list from hep-ph)
Further understanding the nature of $Ω (2012)$ within a chiral quark model
Hui-Hua Zhong🇨🇳 · Ru-Hui Ni🇨🇳 · Mu-Yang Chen🇨🇳 · Xian-Hui Zhong🇨🇳 · Ju-Jun Xie🇨🇳
In our previous works, we have analyzed the two-body strong decays of the low-lying $Ω$ baryon states within a chiral quark model. The results show that the $Ω (2012)$ resonance favors the three-quark state with $J^{P} = 3/ 2^{-}$ classified in the quark model. With this assignment, in the present work we further study the three-body strong decay $Ω (2012) \to Ξ^{*} (1530) K ˉ \to Ξ π K ˉ$ and coupled-channel effects on $Ω (2012)$ from nearby channels $Ξ K ˉ$ , $Ω η$ and $Ξ^{*} (1530) K ˉ$ within the chiral quark model as well. It is found that the $Ω (2012)$ resonance has a sizeable decay rate into the three-body final state $Ξ π K ˉ$ . The predicted ratio $R_{Ξ K ˉ}^{Ξ π K ˉ} = B [Ω (2012) \to Ξ^{*} (1530) K ˉ \to Ξ π K ˉ] / B [Ω (2012) \to Ξ K ˉ] ≃ 12%$ is close to the up limit $11%$ measured by the Belle Collaboration in 2019, however, our predicted ratio is too small to be comparable with the recent data $0.97 \pm 0.31$ . Furthermore, our results show that the coupled-channel effects on the $Ω (2012)$ is not large, its components should be dominated by the bare three-quark state, while the proportion of the molecular components is only $\sim 16%$ . To clarify the nature of $Ω (2012)$ , the ratio $R_{Ξ K ˉ}^{Ξ π K ˉ}$ is expected to be tested by other experiments.
Comments:
7 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2209.09398 [pdf]
CPC(2023)·19 citations
08
[Submitted on 20 Sept 2022] (cross-list from hep-ph)
Systems Dominated by Exchange Particles
V.A. Karmanov🇷🇺
As well known, the spectrum of a non-relativistic two-body system interacting by the Coulomb potential is the Balmer series $E_{n} = \frac{α ^{2} m}{4 n ^{2}}$ produced by the Schrödinger equation. In 1954, Wick and Cutkosky have found, in the Bethe-Salpeter equation framework, that for $α > \frac{π}{4}$ the relativistic effects result in new levels (in addition to the Balmer series). However, the physical nature of these new states remained unclear and therefore their existence was being questioned. We have recently shown that these extra states are dominated by the exchange (massless) particles, moving with speed of light. That's why they did not appear in the non-relativistic (Schrödinger) framework.
Comments:
10 pages, 4 figures. Talk at the 39-th International Workshop on Nuclear Theory, the Rila Mountains, Bulgaria, 3-9 July 2022. Will be published in Nuclear Theory, 39 (2022)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.09816 [pdf]
Nucl.Theor.(2022)·0 citations
09
[Submitted on 20 Sept 2022] (cross-list from hep-ph)
Entanglement between Valence and Sea Quarks in Hadrons of 1+1 Dimensional QCD
Peter J. Ehlers🇺🇸
The conceptual interpretation of valence- and sea-quark separation, which is a key aspect of the parton model and of an intuitive picture of hadron structure, becomes obscured by quantum effects in QCD. This suggests that there may be measures of entanglement between quark degrees of freedom that are present in QCD, but absent in the intuitive picture with a clear valence-sea (VS) separation. In this paper, we define the first rigorous measure of VS entanglement in QCD in an attempt to bring conceptual clarity to this issue, and, potentially, to find a measure of the applicability of the parton model to QCD bound states. This VS entanglement vanishes in the large- $N_{c}$ limit, and it remains low when finite- $N_{c}$ states resemble their large- $N_{c}$ counterparts. We perform a numerical study of VS entanglement in 1+1 dimensional discrete light-cone quantized QCD, and in the process develop a method for building the color-singlet basis of 1+1d QCD that is manifestly complete and orthogonal by construction. We calculate this VS entanglement entropy for the first time and find that it is relatively low for the first few excited states of both mesons and baryons compared to all other states in the spectrum, with the VS entropy of ground state hadrons providing a minimum. We also see that for ground state mesons the entropy is well described in the $1/ N_{c}$ approximation. These results suggest that low energy hadrons may be the only QCD bound states for which the large- $N_{c}$ expansion, and perhaps the parton model, provide an accurate description. This work also provides the first evidence that the VS entanglement entropy of QCD in 3+1d, which would likely serve as an order parameter for the transition between quark and hadron degrees of freedom, may be perturbatively accessible through a large- $N_{c}$ expansion.
Comments:
58 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2209.09867 [pdf]
Annals Phys.(2023)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE

Causal, stable first-order viscous relativistic hydrodynamics with ideal gas microphysics

D∗ and Ds∗​ distribution amplitudes from Bethe-Salpeter wave functions

Large-Momentum Effective Theory vs. Short-Distance Operator Expansion: Contrast and Complementarity

Further understanding the nature of Ω(2012) within a chiral quark model

Systems Dominated by Exchange Particles

Entanglement between Valence and Sea Quarks in Hadrons of 1+1 Dimensional QCD

Affiliations

$D^{}$ and $D_{s}^{}$ distribution amplitudes from Bethe-Salpeter wave functions

Further understanding the nature of $Ω (2012)$ within a chiral quark model