Nuclear Theory·nucl-th

Wednesday·November 4, 2020

13 papers—6 primary·7 cross-listed

07
[Submitted on 2 Nov 2020] (cross-list from hep-th)
Geometry and entanglement in the scattering matrix
Silas R. Beane🇺🇸 · Roland C. Farrell🇺🇸
A formulation of nucleon-nucleon scattering is developed in which the S-matrix, rather than an effective-field theory (EFT) action, is the fundamental object. Spacetime plays no role in this description: the S-matrix is a trajectory that moves between RG fixed points in a compact theory space defined by unitarity. This theory space has a natural operator definition, and a geometric embedding of the unitarity constraints in four-dimensional Euclidean space yields a flat torus, which serves as the stage on which the S-matrix propagates. Trajectories with vanishing entanglement are special geodesics between RG fixed points on the flat torus, while entanglement is driven by an external potential. The system of equations describing S-matrix trajectories is in general complicated, however the very-low-energy S-matrix -- that appears at leading-order in the EFT description -- possesses a UV/IR conformal invariance which renders the system of equations integrable, and completely determines the potential. In this geometric viewpoint, inelasticity is in correspondence with the radius of a three-dimensional hyperbolic space whose two-dimensional boundary is the flat torus. This space has a singularity at vanishing radius, corresponding to maximal violation of unitarity. The trajectory on the flat torus boundary can be explicitly constructed from a bulk trajectory with a quantifiable error, providing a simple example of a holographic quantum error correcting code.
Comments:
44 pages, 18 figures. References and clarifications added in v2
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2011.01278 [pdf]
Annals Phys.(2021)·38 citations
08
[Submitted on 3 Nov 2020] (cross-list from hep-ph)
Multi-system Bayesian constraints on the transport coefficients of QCD matter
D. Everett🇺🇸 · W. Ke🇺🇸 · J.-F. Paquet🇺🇸 · G. Vujanovic🇺🇸 · S. A. Bass🇺🇸 · L. Du🇺🇸 · C. Gale🇨🇦 · M. Heffernan🇨🇦 · U. Heinz🇺🇸 · D. Liyanage🇺🇸 · M. Luzum🇧🇷 · A. Majumder🇺🇸 and 36 other authors
We study the properties of the strongly-coupled quark-gluon plasma with a multistage model of heavy ion collisions that combines the T $_{R}$ ENTo initial condition ansatz, free-streaming, viscous relativistic hydrodynamics, and a relativistic hadronic transport. A model-to-data comparison with Bayesian inference is performed, revisiting assumptions made in previous studies. The role of parameter priors is studied in light of their importance towards the interpretation of results. We emphasize the use of closure tests to perform extensive validation of the analysis workflow before comparison with observations. Our study combines measurements from the Large Hadron Collider and the Relativistic Heavy Ion Collider, achieving a good simultaneous description of a wide range of hadronic observables from both colliders. The selected experimental data provide reasonable constraints on the shear and the bulk viscosities of the quark-gluon plasma at $T \sim$ 150-250 MeV, but their constraining power degrades at higher temperatures $T ≳ 250$ MeV. Furthermore, these viscosity constraints are found to depend significantly on how viscous corrections are handled in the transition from hydrodynamics to the hadronic transport. Several other model parameters, including the free-streaming time, show similar model sensitivity while the initial condition parameters associated with the T $_{R}$ ENTo ansatz are quite robust against variations of the particlization prescription. We also report on the sensitivity of individual observables to the various model parameters. Finally, Bayesian model selection is used to quantitatively compare the agreement with measurements for different sets of model assumptions, including different particlization models and different choices for which parameters are allowed to vary between RHIC and LHC energies.
Comments:
51 pages, including 35 figures and 8 appendices, long companion paper to arXiv:2010.03928. A useful visualization tool to see the effect of varying individual model parameters on physical observables can be found at jetscape.org/sims-widget. Some references and discussion added. This version submitted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.01430 [pdf]
PRC(2021)·403 citations
09
[Submitted on 3 Nov 2020] (cross-list from hep-lat)
Deconfinement and Hadron Resonance Gas for Heavy Quarks
Peter Petreczky🇺🇸
I discuss the deconfinement transition in 2+1 flavor QCD in terms of Polyakov loops as well as the hadron resonance gas for hadrons containing static quarks and charm quarks.
Comments:
11 pages, LaTeX, 4 figures, Invited talk at Workshop on Criticality in QCD and Hadron Resonance Gas, July 29-31, 2020, Wroclaw, Poland, to be published in the proceedings, typos corrected
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.01466 [pdf]
Acta Phys.Polon.Supp.(2021)·2 citations
10
[Submitted on 31 Oct 2020] (cross-list from hep-ph)
Jet quenching with $T$ -dependent running coupling
B.G. Zakharov🇷🇺
We perform an analysis of jet quenching in heavy ion collisions at RHIC and LHC energies with the temperature dependent running QCD coupling. Our results show that the $T$ -dependent QCD coupling largely eliminates the difference between the optimal values of $α_{s}$ for the RHIC and LHC energies. It may be viewed as direct evidence of the increase of the thermal suppression of $α_{s}$ with rising temperature.
Comments:
7 pages, 3 figures, accepted for publication in JETP Letters. arXiv admin note: text overlap with arXiv:2007.09772
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.01526 [pdf]
JETP Lett.(2020)·5 citations
11
[Submitted on 3 Nov 2020] (cross-list from nucl-ex)
Nuclear Moments of Germanium Isotopes around $N$ = 40
A. Kanellakopoulos🇧🇪 · X. F. Yang🇨🇳 · M. L. Bissell🇬🇧 · M. L. Reitsma🇳🇱 · S. W. Bai🇨🇳 · J. Billowes🇬🇧 · K. Blaum🇩🇪 · A. Borschevsky🇳🇱 · B. Cheal🇬🇧 · C. S. Devlin🇬🇧 · R. F. Garcia Ruiz🇨🇭 · H. Heylen🇨🇭 and 15 other authors
Collinear laser spectroscopy measurements were performed on $^{69, 71, 73}$ Ge isotopes ( $Z = 32$ ) at ISOLDE-CERN. The hyperfine structure of the $4 s^{2} 4 p^{2}^{3} P_{1} \to 4 s^{2} 4 p 5 s^{3} P_{1}^{o}$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated using state-of-the-art atomic relativistic Fock-space coupled-cluster calculations. A new $^{73}$ Ge quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{s}$ = $-$ 0.198(4) b, in excellent agreement with the literature value from molecular calculations. The moments of $^{69}$ Ge have been revised: $μ$ = +0.920(5) $μ_{N}$ and $Q_{s}$ = +0.114(8) b, and those of $^{71}$ Ge have been confirmed. The experimental moments around $N = 40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave function configurations, although their $g$ -factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N = 40$ .
Comments:
accepted in Phys. Rev. C., in production
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.01659 [pdf]
PRC(2020)·15 citations
12
[Submitted on 3 Nov 2020] (cross-list from physics.data-an)
Accuracy and precision of the estimation of the number of missing levels in chaotic spectra using long-range correlations
I. Casal🇪🇸 · L. Muñoz🇪🇸 · R.A. Molina🇪🇸
We study the accuracy and precision for estimating the fraction of observed levels $φ$ in quantum chaotic spectra through long-range correlations. We focus on the main statistics where theoretical formulas for the fraction of missing levels have been derived, the $Δ_{3}$ of Dyson and Mehta and the power spectrum of the $δ_{n}$ statistic. We use Monte Carlo simulations of the spectra from the diagonalization of Gaussian Orthogonal Ensemble matrices with a definite number of levels randomly taken out to fit the formulas and calculate the distribution of the estimators for different sizes of the spectrum and values of $φ$ . A proper averaging of the power spectrum of the $δ_{n}$ statistic needs to be performed for avoiding systematic errors in the estimation. Once the proper averaging is made the estimation of the fraction of observed levels has quite good accuracy for the two methods even for the lowest dimensions we consider $d = 100$ . However, the precision is generally better for the estimation using the power spectrum of the $δ_{n}$ as compared to the estimation using the $Δ_{3}$ statistic. This difference is clearly bigger for larger dimensions. Our results show that a careful analysis of the value of the fit in view of the ensemble distribution of the estimations is mandatory for understanding its actual significance and give a realistic error interval.
Comments:
10 pages, 9 figures
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); cond-mat.other (cond-mat.other); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2011.01667 [pdf]
Eur.Phys.J.Plus(2021)·4 citations
13
[Submitted on 3 Nov 2020] (cross-list from hep-ph)
The $P_{cs} (4459)$ pentaquark from a combined effective field theory and phenomenological perspective
Fang-Zheng Peng🇨🇳 · Mao-Jun Yan🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳
The observation of the $P_{cs} (4459)$ by the LHCb collaboration adds a new member to the set of known hidden-charm pentaquarks, which includes the $P_{c} (4312)$ , $P_{c} (4440)$ and $P_{c} (4457)$ . The $P_{cs} (4459)$ is expected to have the light-quark content of a $Λ$ baryon ( $I = 0$ , $S = - 1$ ), but its spin is unknown. Its closeness to the $D ˉ^{*} Ξ_{c}$ threshold -- $4478 MeV$ in the isospin-symmetric limit -- suggests the molecular hypothesis as a plausible explanation for the $P_{cs} (4459)$ . While in the absence of coupled-channel dynamics heavy-quark spin symmetry predicts the two spin-states of the $D ˉ^{*} Ξ_{c}$ to be degenerate, power counting arguments indicate that the coupling with the nearby $D ˉ Ξ_{c}^{'}$ and $D ˉ Ξ_{c}^{*}$ channels might be a leading order effect. This generates a hyperfine splitting in which the $J = \frac{3}{2}$ $D ˉ^{*} Ξ_{c}$ pentaquark will be lighter than the $J = \frac{1}{2}$ configuration, which we estimate to be of the order of $5 - 15 MeV$ . We also point out an accidental symmetry between the $P_{cs} (4459)$ and $P_{c} (4440/4457)$ potentials. Finally, we argue that the spectroscopy and the $J / ψ Λ$ decays of the $P_{cs} (4459)$ might suggest a marginal preference for $J = \frac{3}{2}$ over $J = \frac{1}{2}$ .
Comments:
16 pages, 1 figure; includes discussions on power counting, the J=1/2,3/2 hyperfine splitting, saturation, phenomenological relation between the Pcs(4459) and Pc(4440/4457) potentials, decay to $J / ψ Λ$ , etc
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.01915 [pdf]
EPJC(2021)·101 citations

Affiliations

first authorsco-authorsvia INSPIRE

Geometry and entanglement in the scattering matrix

Multi-system Bayesian constraints on the transport coefficients of QCD matter

Deconfinement and Hadron Resonance Gas for Heavy Quarks

Jet quenching with T-dependent running coupling

Nuclear Moments of Germanium Isotopes around N = 40

Accuracy and precision of the estimation of the number of missing levels in chaotic spectra using long-range correlations

The Pcs​(4459) pentaquark from a combined effective field theory and phenomenological perspective

Affiliations

Jet quenching with $T$ -dependent running coupling

Nuclear Moments of Germanium Isotopes around $N$ = 40

The $P_{cs} (4459)$ pentaquark from a combined effective field theory and phenomenological perspective