Nuclear Theory·nucl-th

Wednesday·March 1, 2023

6 papers—5 primary·1 cross-listed

01
[Submitted on 27 Feb 2023]
Bayesian calibration of viscous anisotropic hydrodynamic simulations of heavy-ion collisions
Dananjaya Liyanage🇺🇸 · Özge Sürer🇺🇸 · Matthew Plumlee🇺🇸 · Stefan M. Wild🇺🇸 · Ulrich Heinz🇺🇸
Due to large pressure gradients at early times, standard hydrodynamic model simulations of relativistic heavy-ion collisions do not become reliable until $O (1)$ \,fm/ $c$ after the collision. To address this one often introduces a pre-hydrodynamic stage that models the early evolution microscopically, typically as a conformal, weakly interacting gas. In such an approach the transition from the pre-hydrodynamic to the hydrodynamic stage is discontinuous, introducing considerable theoretical model ambiguity. Alternatively, fluids with large anisotropic pressure gradients can be handled macroscopically using the recently developed Viscous Anisotropic Hydrodynamics (VAH). In high-energy heavy-ion collisions VAH is applicable already at very early times, and at later times transitions smoothly into conventional second-order viscous hydrodynamics (VH). We present a Bayesian calibration of the VAH model with experimental data for Pb--Pb collisions at the LHC at $s_{NN} = 2.76$ \,TeV. We find that the VAH model has the unique capability of constraining the specific viscosities of the QGP at higher temperatures than other previously used models.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.14184 [pdf]
PRC(2023)·35 citations
02
[Submitted on 28 Feb 2023]
Higgs response and pair condensation energy in superfluid nuclei
Kengo Takahashi · Yusuke Matsuda · Masayuki Matsuo
The pairing correlation in nuclei causes a characteristic excitation, known as the pair vibration, which is populated by the pair transfer reactions. Here we introduce a new method of characterizing the pair vibration by employing an analogy to the Higgs mode, which emerges in infinite superconducting/superfluid systems as a collective vibrational mode associated with the amplitude oscillation of the Cooper pair condensate. The idea is formulated by defining a pair-transfer probe, the Higgs operator, and then describing the linear response and the strength function to this probe. We will show that the pair condensation energy in nuclei can be extracted with use of the strength sum and the static polarizability of the Higgs response. In order to demonstrate and validate the method, we perform for Sn isotopes numerical analysis based the quasi-particle random phase approximation to the Skyrme-Hartree-Fock-Bogoliubov model. We discuss a possibility to apply this new scheme to pair transfer experiment.
Comments:
31 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Superconductivity (cond-mat.supr-con); Nuclear Experiment (nucl-ex)
arXiv:
2302.14214 [pdf]
PTEP(2023)·5 citations
03
[Submitted on 28 Feb 2023]
Effects of $N (2080) 3/2^{-}$ and $N (2270) 3/ 2^{-}$ molecules on $K^{*} Σ$ photoproduction
Di Ben🇨🇳 · Ai-Chao Wang🇨🇳 · Fei Huang🇨🇳 · Bing-Song Zou🇨🇳
In the present work, we re-analyze the available data for $γ p \to K^{*+} Σ^{0}$ and $γ p \to K^{* 0} Σ^{+}$ by considering the contributions from the $N (2080) 3/2^{-}$ and $N (2270) 3/ 2^{-}$ molecules instead of any nucleon resonances in the $s$ channel, where the $N (2080) 3/ 2^{-}$ was proposed to be a $K^{*} Σ$ molecule as the strange partner of the $P_{c}^{+} (4457)$ hadronic molecular state, and the $N (2270) 3/ 2^{-}$ was assumed to be a $K^{*} Σ^{*}$ molecule as the strange partner of the $D ˉ^{*} Σ_{c}^{*}$ bound states that are predicated as members in the same heavy-quark spin symmetry multiplet as the $P_{c}$ states. It turns out that all the available cross-section data can be well reproduced, indicating that the molecular structures of the possible $N (2080) 3/2^{-}$ and $N (2270) 3/ 2^{-}$ states are compatible with the available data for $K^{*} Σ$ photoproduction reactions. Further analysis shows that for both $γ p \to K^{*+} Σ^{0}$ and $γ p \to K^{* 0} Σ^{+}$ reactions, the $N (2080) 3/2^{-}$ exchange provides dominant contributions to the cross-sections in the near-threshold energy region, and significant contributions from the $N (2270) 3/ 2^{-}$ exchange to the cross-sections in the higher energy region are also found. Predictions of the beam asymmetry $Σ$ , target asymmetry $T$ , and recoil baryon asymmetry $P$ are presented and compared with those from our previous work. Measurements of the data on these observables are called on to further constrain the reaction mechanisms of $K^{*} Σ$ photoproduction reactions and to verify the molecular scenario of the $N (2080) 3/2^{-}$ and $N (2270) 3/ 2^{-}$ states.
Comments:
10 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2302.14308 [pdf]
PRC(2023)·17 citations
04
[Submitted on 28 Feb 2023]
New perspectives on spectroscopic factor quenching from reactions
Chloë Hebborn · Filomena M. Nunes · Amy E. Lovell
The evolution of single-particle strengths as the neutron-to-proton asymmetry changes informs us of the importance of short- and long-range correlations in nuclei and has therefore been extensively studied for the last two decades. Surprisingly, the strong asymmetry dependence of these strengths and their extreme values for highly-asymmetric nuclei inferred from knockout reaction measurements on a target nucleus are not consistent with what is extracted from electron-induced, transfer, and quasi-free reaction data, constituting a two-decade old puzzle. This work presents the first consistent analysis of one-nucleon transfer and one-nucleon knockout data, in which theoretical uncertainties associated with the nucleon-nucleus effective interactions considered in the reaction models are quantified using a Bayesian analysis. Our results demonstrate that, taking into account these uncertainties, the spectroscopic strengths of loosely-bound nucleons extracted from both probes agree with each other and, although there are still discrepancies for deeply-bound nucleons, the slope of the asymmetry dependence of the single-particle strengths inferred from transfer and knockout reactions are consistent within $1 σ$ . Both probes are consistent with a small asymmetry dependence of these strengths. The uncertainties obtained in this work represent a lower bound and are already significantly larger than the original estimates.
Comments:
14 pages: 7 pages of the main text (including one and a half of reference) and 7 pages of supplemental material. Accepted for publication in Phys. Rev. Lett
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2302.14343 [pdf]
PRL(2023)·17 citations
05
[Submitted on 28 Feb 2023]
Signatures of quark deconfinement through the r-modes of twin stars
P. Laskos-Patkos🇬🇷 · Ch.C. Moustakidis🇬🇷
The observation and distinction of two compact stars with an identical mass but a different radius would be a clear sign of hadron-quark phase transition in nuclear matter. Motivated by studies searching for significant deviations in the observables of twin stars, we investigate the differences that manifest in their r-mode instability windows and spin-down evolution. Firstly, we obtain a set of hybrid equations of state (which predict the existence of a third stable branch of compact objects) by employing the well-known Maxwell construction within the phenomenological framework of constant speed of sound parametrization. Then, we systematically study the influence of certain parameters, such as the energy density jump (in the resulting hybrid equation of state) and the crust elasticity, on the deviations appearing in the r-mode instability windows and spin-down evolution of twin stars. We conclude that two stars with an identical mass and fairly similar spin frequency and temperature, may behave differently with respect to r-modes. Thus, the future possible detection of gravitational waves (due to unstable r-modes) from a star laying in the stable region of the frequency-temperature plane would be a strong indication for the existence of twin stars. Furthermore, we consider current data for the spin frequencies and temperatures of observed pulsars and compare them to the predictions made from equations of state employed in this study. We find that, depending on the transition density and the rigidness of the crust, hybrid equations of state may be a viable solution for the explanation of existing data.
Comments:
v1: 14 pages, 7 figures, 2 tables; v2: updated to match the published version; accepted for publication in Physical Review D
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2302.14537 [pdf]
PRD(2023)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE

Bayesian calibration of viscous anisotropic hydrodynamic simulations of heavy-ion collisions

Higgs response and pair condensation energy in superfluid nuclei

Effects of N(2080)3/2− and N(2270)3/2− molecules on K∗Σ photoproduction

New perspectives on spectroscopic factor quenching from reactions

Signatures of quark deconfinement through the r-modes of twin stars

Affiliations

Effects of $N (2080) 3/2^{-}$ and $N (2270) 3/ 2^{-}$ molecules on $K^{*} Σ$ photoproduction