Nuclear Theory·nucl-th

Monday·March 4, 2024

12 papers—4 primary·8 cross-listed

01
[Submitted on 1 Mar 2024]
Five-dimensional collective Hamiltonian with improved inertial functions
Kouhei Washiyama · Nobuo Hinohara · Takashi Nakatsukasa
Background: To describe shape fluctuations associated with large-amplitude collective motion in the quadrupole degrees of freedom, the five-dimensional collective Hamiltonian (5DCH) has been widely used. The inertial functions in the 5DCH are microscopically calculated with the energy density functional (EDF) theory employing the cranking formula. However, since the cranking formula ignores dynamical residual effects, it is known to fail to reproduce the correct inertial functions, for instance, the total mass for the translational motion. Purpose: We aim to resolve problems of the insufficient description of the inertial functions in the 5DCH. We provide a practical method to include the dynamical residual effects in the inertial functions that depend on the quadrupole deformation parameters $β$ and $γ$ . Methods: We use the local quasiparticle random-phase approximation (LQRPA) based on the constrained Hartree-Fock-Bogoliubov states in the $β$ -- $γ$ plane with the Skyrme EDF. The finite-amplitude method is used for efficient computations of the LQRPA. Results: The inertial functions evaluated with the LQRPA significantly increase from the ones with the cranking formula due to the dynamical residual effects. This increase also shows a strong $β$ -- $γ$ dependence. We show an application of the present method to a transitional nucleus $^{110}$ Pd. The low-lying positive-parity spectra are well reproduced with the LQRPA inertial functions. Conclusions: We clarify the importance of the dynamical residual effects in the inertial functions of the 5DCH for the description of the low-lying spectra. The 5DCH with the improved inertial functions provides a reliable and efficient description of low-lying spectra in nuclei associated with the quadrupole shape fluctuation.
Comments:
7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2403.00214 [pdf]
PRC(2024)·6 citations
02
[Submitted on 1 Mar 2024]
Novel Pauli blocking method in quantum molecular dynamics type models
Xiang Chen · Junping Yang · Ying Cui · Kai Zhao · Zhuxia Li · Yingxun Zhang
In this work, we propose a novel method for calculating the occupation probability in the Pauli blocking of the quantum molecular dynamics type models. This method refines the description of the Pauli blocking ratio in the nuclear matter and that in the finite nucleus. The influence of the new Pauli blocking method on the heavy ion collisions observables, such as the charge distribution, the free neutron to proton yield ratios, and the extracted physical quantities, such as the in-medium nucleon-nucleon cross sections, are investigated. For the extracted in-medium nucleon-nucleon cross sections, our results show that it will be enhanced 1.1 $-$ 2.5 times than that with the conventional Pauli blocking method at the beam energy less than 150 MeV/u, which highlights the importance of a refined Pauli blocking method for developing an advanced transport model to describe complex heavy ion collisions.
Comments:
8 pages, 5 figures, accepted for PRC Letter
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2403.00343 [pdf]
PRC(2024)·1 citation
03
[Submitted on 1 Mar 2024]
Production of Resonances in Partial Chemical Equilibrium
Boris Tomasik🇸🇰 · Sandor Lokos🇸🇰
Within the model of partial chemical equilibrium (PCE) we calculate the multiplicity ratios of selected unstable resonances to given stable species. We focus on those ratios that have been measured either in Pb+Pb collisions at the LHC or in Au+Au collisions at the top RHIC energy. The model provides an interpretation how in an expanding hadronic fireball with decreasing temperature the final numbers of stable hadrons after decays of all resonances remain unchanged. Each stable species acquires its own chemical potential and the resonances are kept in equilibrium with them. Multiplicities of unstable resonances provide a test of this scenario. We observe that the ratios of $K^{*} / K$ and $ρ^{0} / π$ fit reasonably well into the picture of single kinetic freeze-out of the single-particle spectra, but the $ϕ$ -meson and hyperon resonances are not reproduced by this model.
Comments:
8 pages, 6 figures, contribution to the Proceedings from XVI WPCF & VI Resonance Workshop, Nov. 6-10, 2023, Catania, Italy
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2403.00427 [pdf]
Nuovo Cim.C(2025)·0 citations
04
[Submitted on 1 Mar 2024]
The role of the likelihood for elastic scattering uncertainty quantification
C. D. Pruitt · A. E. Lovell · C. Hebborn · F. M. Nunes
Background: Analyses of elastic scattering with the optical model (OMP) are widely used in nuclear reactions. Purpose: Previous work compared a traditional frequentist approach and a Bayesian approach to quantify uncertainties in the OMP. In this study, we revisit this comparison and consider the role of the likelihood used in the analysis. Method: We compare the Levenberg-Marquardt algorithm for $χ^{2}$ minimization with Markov Chain Monte Carlo sampling to obtain parameter posteriors. Following previous work, we consider how results are affected when $χ^{2}$ /N is used for the likelihood function, N being the number of data points, to account for possible correlations in the model and underestimation of the error in the data. Results: We analyze a simple linear model and then move to OMP analysis of elastic angular distributions using a) a 5-parameter model and b) a 6-parameter model. In the linear model, the frequentist and Bayesian approaches yield consistent optima and uncertainty estimates. The same is qualitatively true for the 5-parameter OMP analysis. For the 6-parameter OMP analysis, the parameter posterior is no longer well-approximated by a Gaussian and a covariance-based frequentist prediction becomes unreliable. In all cases, when the Bayesian approach uses $χ^{2}$ /N in the likelihood, uncertainties increase by $N$ . Conclusions: When the parameter posterior is near-Gaussian and the same likelihood is used, the frequentist and Bayesian approaches recover consistent parameter uncertainty estimates. If the parameter posterior has significant higher moments, the covariance-only frequentist approach becomes unreliable and the Bayesian approach should be used. Empirical coverage can serve as an important internal check for uncertainty estimation, providing red flags for uncertainty analyses.
Comments:
9 pages, 6 figures. Submitted for publication to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2403.00753 [pdf]
PRC(2024)·11 citations
05
[Submitted on 29 Feb 2024] (cross-list from hep-ph)
Pole properties of a resonance: When to subtract partial-decay widths to obtain the pole widths
J. A. Oller
When a resonance lies near the threshold of a heavier channel, an interesting feature can occur. The paradigmatic example employed here is the scalar isoscalar $f_{0} (980)$ resonance that couples to the lighter $π π$ and heavier $K K ˉ$ channels. It is shown that the decay width is given by the sum or subtraction of the partial decay widths depending on whether the pole lies in the Riemann sheet that is contiguous with the physical one above or below the $K K ˉ$ threshold, respectively. Next, we show that the usually disregarded renormalization of bare parameters in Flatté or energy-dependent Breit-Wigner parameterizations is essential to extract physical information. The compositeness of the $f_{0} (980)$ by using a Flatté parameterization matched to reproduce the pole properties obtained from Roy equations and other analytic constraints is evaluated.
Comments:
6 pages, 2 tables. Talk given at Excited QCD 2024, Benasque, Spain, January 2024
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.00135 [pdf]
Acta Phys.Polon.Supp.(2024)·0 citations
06
[Submitted on 1 Mar 2024] (cross-list from astro-ph.HE)
Neural Simulation-Based Inference of the Neutron Star Equation of State directly from Telescope Spectra
Len Brandes🇩🇪 · Chirag Modi🇺🇸 · Aishik Ghosh🇺🇸 · Delaney Farrell🇺🇸 · Lee Lindblom🇺🇸 · Lukas Heinrich🇩🇪 · Andrew W. Steiner🇺🇸 · Fridolin Weber🇺🇸 · Daniel Whiteson🇺🇸
Neutron stars provide a unique opportunity to study strongly interacting matter under extreme density conditions. The intricacies of matter inside neutron stars and their equation of state are not directly visible, but determine bulk properties, such as mass and radius, which affect the star's thermal X-ray emissions. However, the telescope spectra of these emissions are also affected by the stellar distance, hydrogen column, and effective surface temperature, which are not always well-constrained. Uncertainties on these nuisance parameters must be accounted for when making a robust estimation of the equation of state. In this study, we develop a novel methodology that, for the first time, can infer the full posterior distribution of both the equation of state and nuisance parameters directly from telescope observations. This method relies on the use of neural likelihood estimation, in which normalizing flows use samples of simulated telescope data to learn the likelihood of the neutron star spectra as a function of these parameters, coupled with Hamiltonian Monte Carlo methods to efficiently sample from the corresponding posterior distribution. Our approach surpasses the accuracy of previous methods, improves the interpretability of the results by providing access to the full posterior distribution, and naturally scales to a growing number of neutron star observations expected in the coming years.
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.00287 [pdf]
JCAP(2024)·28 citations
07
[Submitted on 1 Mar 2024] (cross-list from hep-ph)
Charge-conjugation asymmetry and molecular content: the $D_{s 0}^{*} (2317)^{\pm}$ in matter
Victor Montesinos🇪🇸 · Miguel Albaladejo🇪🇸 · Juan Nieves🇪🇸 · Laura Tolos🇪🇸
We analyze the modifications that a dense nuclear medium induces in the $D_{s 0}^{*} (2317)^{\pm}$ and $D_{s 1} (2460)^{\pm}$ . In the vacuum, we consider them as isoscalar $D^{(*)} K$ and $D^{(*)} K$ $S$ -wave bound states, which are dynamically generated from effective interactions that lead to different Weinberg compositeness scenarios. Matter effects are incorporated through the two-meson loop functions, taking into account the self energies that the $D^{(*)}$ , $D^{(*)}$ , $K$ , and $K$ develop when embedded in a nuclear medium. Although particle-antiparticle [ $D_{s 0, s 1}^{(*)} (2317, 2460)^{+}$ versus $D_{s 0, s 1}^{(*)} (2317, 2460)^{-}$ ] lineshapes are the same in vacuum, we find extremely different density patterns in matter. This charge-conjugation asymmetry mainly stems from the very different kaon and antikaon interaction with the nucleons of the dense medium. We show that the in-medium lineshapes found for these resonances strongly depend on their $D^{(*)} K$ / $D^{(*)} K$ molecular content, and discuss how this novel feature can be used to better determine/constrain the inner structure of these exotic states.
Comments:
14 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.00451 [pdf]
PLB(2024)·9 citations
08
[Submitted on 1 Mar 2024] (cross-list from hep-ph)
A Light-Front Model for the Transition Distribution Amplitudes for Backward Timelike Compton Scattering
B. Pasquini🇮🇹 · A. Schiavi🇮🇹
To access information on the internal structure of the nucleon, data from a variety of scattering experiments can be analyzed, in regimes where the information factorizes from an otherwise known scattering amplitude. A recent development, promising new insight, is the study of exclusive reactions in the backward kinematical region, where the information can be encoded in Transition Distribution Amplitudes (TDAs). We model the photon-to-nucleon TDAs, entering the factorized description of backward Timelike Compton Scattering, using techniques of light-front dynamics to integrate information from a quark model for the photon and the nucleon. We include the results of numerical predictions that could inform further experiments at Jefferson Lab and the future Electron--Ion Collider.
Comments:
20 pages, 10 figures, 6 tables; updated plots after numerical improvements
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2403.00614 [pdf]
PRD(2024)·4 citations
09
[Submitted on 1 Mar 2024] (cross-list from hep-ph)
Hadron momentum spectra from analytical solutions of relativistic hydrodynamics
Mahammad Sabir Ali🇮🇳 · Deeptak Biswas🇮🇳 · Amaresh Jaiswal🇮🇳 · Sushant K. Singh🇮🇹
We present analytical solution of relativistic hydrodynamics for a system having cylindrical symmetry with boost-invariant longitudinal expansion and Hubble-like transverse expansion. We also consider analytical solution for Hubble-like spherically expanding system. For these two cases, we calculate analytical expression for transverse momentum spectra of hadrons, at constant temperature freeze-out hypersurface using Cooper-Frye prescription. We compare our results for transverse momentum spectra with experimental results from Large Hadron Collider and CERN SPS where one expects cylindrical and spherical geometry of the fireball, respectively. In the case of low-energy collisions with spherical geometry, we calculate rapidity spectra and compare with the results from CERN SPS.
Comments:
Matched with the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.00624 [pdf]
EPJC(2025)·3 citations
10
[Submitted on 1 Mar 2024] (cross-list from hep-ph)
Pseudoscalar Mesons and Emergent Mass
K. Raya🇪🇸 · A. Bashir🇪🇸 · D. Binosi🇮🇹 · C. D. Roberts🇨🇳 · J. Rodríguez-Quintero🇪🇸
Despite its role in the continuing evolution of the Universe, only a small fraction of the mass of visible material can be attributed to the Higgs boson alone. The overwhelmingly dominant share may/should arise from the strong interactions that act in the heart of nuclear matter; namely, those described by quantum chromodynamics. This contribution describes how studying and explaining the attributes of pseudoscalar mesons can open an insightful window onto understanding the origin of mass in the Standard Model and how these insights inform our knowledge of hadron structure. The survey ranges over distribution amplitudes and functions, electromagnetic and gravitational form factors, light-front wave functions, and generalized parton distributions. Advances made using continuum Schwinger function methods and their relevance for experimental efforts are highlighted.
Comments:
Prepared for the special issue of the Few Body Systems journal: "Advances on the Few-Body Problem in Physics - Selected and refereed papers from the 25th European Conference"
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2403.00629 [pdf]
Few Body Syst.(2024)·53 citations
11
[Submitted on 1 Mar 2024] (cross-list from hep-ph)
J/psi-pair production at NLL in TMD factorisation at the LHC
Alice Colpani Serri🇵🇱 · Jelle Bor🇳🇱 · Daniel Boer🇳🇱 · Jean-Philippe Lansberg🇫🇷
J/psi-pair production at the LHC is currently one of the few tools available to probe gluon transverse momentum distributions (TMDs). In this context, data from LHCb in the collider mode have the potential to probe the evolution of the unpolarised-gluon TMDs and to measure the distribution of the linearly-polarised gluon in unpolarised protons for the first time. In this proceedings contribution, improved predictions obtained for the LHC (at sqrt(s) = 13 TeV) up to next-to-leading logarithm (NLL) in TMD factorisation are presented. We show the obtained predictions of transverse-momentum distributions at different invariant masses and rapidities computed in the LHCb acceptance along with PDF uncertainty. We predict the azimuthal modulations of the cross section that arise from linearly-polarised gluons.
Comments:
LaTeX, 6 pages, 4 figures, uses pos.sty. Talk given by A. Colpani Serri at "The European Physical Society Conference on High Energy Physics (EPS-HEP2023)", 21-25 August 2023, Hamburg, Germany; Version to appear in PoS - Proceedings of Science
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2403.00640 [pdf]
PoS(2024)·2 citations
12
[Submitted on 1 Mar 2024] (cross-list from hep-lat)
Nonperturbative Collins-Soper Kernel from Chiral Quarks with Physical Masses
Dennis Bollweg🇺🇸 · Xiang Gao🇺🇸 · Swagato Mukherjee🇺🇸 · Yong Zhao🇺🇸
We present a lattice QCD calculation of the rapidity anomalous dimension of quark transverse-momentum-dependent distributions, i.e., the Collins-Soper (CS) kernel, up to transverse separations of about 1 fm. This unitary lattice calculation is conducted, for the first time, employing the chiral-symmetry-preserving domain wall fermion discretization and physical values of light and strange quark masses. The CS kernel is extracted from the ratios of pion quasi-transverse-momentum-dependent wave functions (quasi-TMDWFs) at next-to-leading logarithmic perturbative accuracy. Also for the first time, we utilize the recently proposed Coulomb-gauge-fixed quasi-TMDWF correlator without a Wilson line. We observe significantly slower signal decay with increasing quark separations compared to the established gauge-invariant method with a staple-shaped Wilson line. This enables us to determine the CS kernel at large nonperturbative transverse separations and find its near-linear dependence on the latter. Our result is consistent with the recent lattice calculation using gauge-invariant quasi-TMDWFs, and agrees with various recent phenomenological parametrizations of experimental data.
Comments:
7 pages, 4 figures; published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2403.00664 [pdf]
PLB(2024)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE