Nuclear Theory·nucl-th

Tuesday·April 30, 2024

15 papers—7 primary·8 cross-listed

01
Contribution to differential $π^{0}$ and $γ_{dir}$ modification in small systems from color fluctuation effects
Dennis V. Perepelitsa🇺🇸
A major complication in the search for jet quenching in proton- or deuteron-nucleus collision systems is the presence of physical effects which influence the experimental determination of collision centrality in the presence of a hard process. For example, in the proton color fluctuation picture, protons with a large Bjorken- $x$ ( $x ≳ 0.1$ ) parton interact more weakly with the nucleons in the nucleus, leading to a smaller (larger) than expected yield in large (small) activity events. A recent measurement by PHENIX compared the yield of neutral pion and direct photon production in $d$ +Au collisions, under the argument that the photon yields correct for such biases, and the difference between the two species is thus attributable to final-state effects (i.e., jet quenching). The main finding suggests a significant degree of jet quenching for hard processes in small systems. In this paper, I argue that the particular photon and pion events selected by PHENIX arise from proton configurations with significantly different Bjorken- $x$ distributions, and thus are subject to different magnitudes of modification in the color fluctuation model. Using the results of a previous global analysis of RHIC and LHC data, I show that potentially all of the pion-to-photon difference in PHENIX data can be described by a proton color fluctuation picture at a quantitative level before any additional physics from final-state effects is required. This finding reconciles the interpretation of the PHENIX measurement with others at RHIC and LHC, which have found no observable evidence for jet quenching in small systems.
nucl-thhep-phnucl-exPRC(2024)·18 citations
02
Fission Fragment Yields Of $^{235}$ U $(n_{t h}, f)$ Evaluated By The CCONE Code System
Futoshi Minato · Osamu Iwamoto
Fission fragment yield evaluations are one of the important nuclear data studies. Fission accompanies various physical observables such as prompt fission neutron, prompt fission gamma, and delayed-neutrons. When evaluating fission fragment yields, a study including correlations among those observables is essentially required. However, fission fragment yield data in the past JENDL libraries have been made by focusing only on experimental fragment yields, decay heats, and delayed neutron yields, and they have not been expanded into a wider range of fission observables. This is because the evaluation method adopted in the JENDL libraries could not study fission fragment yields and particle emissions from fragments simultaneously. To solve this problem, a calculation system with CCONE code is newly developed to estimate not only independent and cumulative fission fragment yields but also prompt fission neutron, prompt fission gamma, decay heats, and delayed-neutrons simultaneously. This system enables us to study a correlation between various fission observables. To determine lots of parameters in this system efficiently, a Gaussian process and a least square fitting are adopted. We tested the calculation system through a thermal neutron-induced fission on $^{235}$ U. In this paper, we demonstrate the performance of the parameter search method and show that experimental fission fragment yield data and other observables resulting from fission are reproduced well by the new calculation system.
nucl-thPRC(2024)·0 citations
03
Prolate-oblate shape transitions and O(6) symmetry in even-even nuclei: A theoretical overview
Dennis Bonatsos · Andriana Martinou · S.K. Peroulis · T.J. Mertzimekis · N. Minkov
Prolate to oblate shape transitions have been predicted in an analytic way in the framework of the Interacting Boson Model (IBM), determining O(6) as the symmetry at the critical point. Parameter-independent predictions for prolate to oblate transitions in various regions on the nuclear chart have been made in the framework of the proxy-SU(3) and pseudo-SU(3) symmetries, corroborated by recent non-relativistic and relativistic mean field calculations along series of nuclear isotopes, with parameters fixed throughout, as well as by shell model calculations taking advantage of the quasi-SU(3) symmetry. Experimental evidence for regions of prolate to oblate shape transitions is in agreement with regions in which nuclei bearing the O(6) dynamical symmetry of the IBM have been identified, lying below major shell closures. In addition, gradual oblate to prolate transitions are seen when crossing major nuclear shell closures, in analogy to experimental observations in alkali clusters.
nucl-thPhys.Scripta(2024)·18 citations
04
Three-body analysis reveals the significant contribution of minor $^{5}$ He $s$ -wave component in $^{6}$ Li $(p, 2 p)^{5}$ He cross section
Shoya Ogawa · Kazuki Yoshida · Yoshiki Chazono · Kazuyuki Ogata
$^{6}$ Li is usually treated as an $α + p + n$ three-body system, and the validity of this picture is important for understanding $^{6}$ Li reactions. The ( $p$ , $2 p$ ) reaction is a powerful method to study the structure of valence nucleons in $^{6}$ Li. Recently, the new experimental data of the $^{6}$ Li( $p$ , $2 p$ ) $^{5}$ He reaction have been obtained and should be analyzed. We investigate the $^{6}$ Li( $p$ , $2 p$ ) $^{5}$ He reaction using the $α + p + n$ three-body wave function of $^{6}$ Li and study the validity of this model. We calculate the $^{6}$ Li wave function by using Gaussian expansion method, and the function is used to obtain the relative wave function between $p$ and $^{5}$ He. We combine the relative wave function with the distorted wave impulse approximation. Our results reproduce the experimental data of the triple differential cross section within about 10\% difference in the absolute values, and contributions from both $p$ - and $s$ -wave states of $^{5}$ He in $^{6}$ Li are found to be important. We can qualitatively understand the $^{6}$ Li( $p$ , $2 p$ ) $^{5}$ He reaction by describing $^{6}$ Li with the three-body model. Contribution from the $s$ -wave component is important in reproducing the experimental data in the zero recoil-momentum region.
nucl-thPRC(2025)·2 citations
05
Exploring system size dependence of jet modification in heavy-ion collisions
Yang He🇨🇳 · Mengxue Zhang🇨🇳 · Maowu Nie🇨🇳 · Shanshan Cao🇨🇳 · Li Yi🇨🇳
In relativistic heavy-ion collisions, jet quenching in quark-gluon plasma (QGP) has been extensively studied, revealing important insights into the properties of the color deconfined nuclear matter. Over the past decade, there has been a surge of interest in the exploration of QGP droplets in small collision systems like $p$ + $p$ or $p$ +A collisions driven by the observation of collective flow phenomena. However, the absence of jet quenching, a key QGP signature, in these systems poses a puzzle. Understanding how jet quenching evolves with system size is crucial for uncovering the underlying physics. In this study, we employ the linear Boltzmann transport (LBT) model to investigate jet modification in $^{96}$ Ru+ $^{96}$ Ru, $^{96}$ Zr+ $^{96}$ Zr, and $^{197}$ Au+ $^{197}$ Au collisions at $s_{N N} = 200$ GeV. Our findings highlight the system size sensitivity exhibited by jet nuclear modification factor ( $R_{AA}$ ) and jet shape ( $ρ$ ), contrasting to the relatively weak responses of jet mass ( $M$ ), girth ( $g$ ) and momentum dispersion ( $p_{T} D$ ) to system size variations. These results offer invaluable insights into the system size dependence of the QGP properties and await experimental validation at the Relativistic Heavy-Ion Collider.
nucl-thhep-phnucl-exPRC(2024)·2 citations
06
Implication of odd-even staggering in the charge radii of calcium isotopes
Rong An · Xiang Jiang · Na Tang · Li-Gang Cao · Feng-Shou Zhang
Inspired by the profoundly observed odd-even staggering and the inverted parabolic-like shape in charge radii along calcium isotopic chain, the ground state properties of calcium isotopes are investigated by constraining the root-mean-square (rms) charge radii under the covariant energy density functionals with effective forces NL3 and PK1. In this work, the pairing correlations are tackled by solving the state-dependent Bardeen-Cooper-Schrieffer equations. The calculated results suggest that the binding energies obtained by the radius constraint method have been slightly changed by about $0.2%$ . But for charge radii, the corresponding results deriving from NL3 and PK1 forces have been increased by about $1.0%$ and $2.0%$ , respectively. This means that charge radius is a more sensitive quantity in the calibrated protocol. Meanwhile, it is found that the reproduced charge radii of calcium isotopes are attributed to the rather strong isospin dependence of effective potential. The odd-even oscillation behavior can also be presented in the proton Fermi energies along calcium isotopic family, but keep opposite trends with respect to the corresponding binding energies and charge radii. As encountered in charge radii, the weakened odd-even oscillation behavior is still emerged from the proton Fermi energies at the neutron numbers $N = 20$ and $28$ as well, but not in binding energies.
nucl-thnucl-exCommun.Theor.Phys.(2025)·0 citations
07
Disentangling the development of collective flow in high energy proton proton collisions with a multiphase transport model
Liang Zheng🇨🇳 · Lian Liu🇨🇳 · Zi-Wei Lin🇺🇸 · Qi-Ye Shou🇨🇳 · Zhong-Bao Yin🇨🇳
In this work, we investigate the collective flow development in high energy proton proton (pp) collisions with a multiphase transport model (AMPT) based on PYTHIA8 initial conditions with a sub-nucleon structure. It is found that the PYTHIA8 based AMPT model can reasonably describe both the charged hadron productions and elliptic flow experimental data measured in pp collisions at $s = 13$ TeV. By turning on the parton and hadron rescatterings in AMPT separately, we find that the observed collective flow in pp collisions is largely developed during the parton evolution, while no significant flow effect can be generated with the pure hadronic rescatterings. It is also shown that the parton escape mechanism is important for describing both the magnitude of the two-particle cumulant and the sign of the four-particle cumulants. We emphasize that the strong mass ordering of the elliptic flow results from the coalescence process in the transport model and can thus be regarded as unique evidence related to the creation of deconfined parton matter in high energy pp collisions.
nucl-thhep-phnucl-exEPJC(2024)·11 citations
08
A three-parameter characterization of neutron stars' mass-radius relation and equation of state
Dmitry D. Ofengeim · Peter S. Shternin · Tsvi Piran
Numerous models of neutron star (NS) equation of state (EoS) exist based on different superdense-matter physics approaches. Nevertheless, some NS properties show universal (EoS-independent) relations. Here, we propose a novel class of such universalities. Despite different physics inputs, a wide class of realistic nucleonic, hyperonic, and hybrid EoS models can be accurately described using only three parameters. For a given EoS, these are the mass and radius of the maximum-mass NS (or pressure and density in its center) and the radius of a half-maximum-mass star. With such a parametrization, we build universal analytic expressions for mass-radius and pressure-density relations. They form a semi-analytic mapping from the mass-radius relation to the EoS in NS cores (the so-called inverse Oppenheimer-Volkoff mapping). This mapping simplifies the process of inferring the EoS from observations of NS masses and radii. Applying it to current NS observations we set new limits on the high-density end of the EoS.
↳ astro-ph.HEnucl-thPRD(2024)·12 citations
09
The properties of $ϕ (2170)$ and its three-body nature
A. Martinez Torres🇧🇷 · Brenda B. Malabarba🇧🇷 · K. P. Khemchandani🇧🇷
We summarize the results we obtained for the partial decay widths of $ϕ (2170)$ into two-body final states formed by a $K ˉ$ and a Kaonic resonance, like $K (1460)$ , $K_{1} (1270)$ , as well as to final states constituted by a $ϕ$ and an $η / η^{'}$ mesons. The results obtained are compared with the values extracted from experimental data on the corresponding branching ratios, which were determined by the BESIII collaboration. A reasonable agreement is found, which together with the previous reproduction of the mass, width, and cross section for the process $e^{+} e^{-} \to ϕ f_{0}$ strongly indicates the molecular nature of $ϕ (2170)$ as a $ϕ K K ˉ$ system.
↳ hep-phnucl-thEPJ Web Conf.(2024)·1 citation
10
Detailed derivation of the $^{3} P_{0}$ strong decay model applied to baryons
T. Aguilar🇪🇨 · A. Capelo-Astudillo🇪🇨 · M. Conde-Correa🇪🇨 · A. Duenas-Vidal🇪🇨 · P. G. Ortega🇪🇸 · J. Segovia🇪🇸
We provide an in-detail derivation through the $^{3} P_{0}$ pair creation model of the transition matrix for a baryon decaying into a meson-baryon system. The meson's analysis was conducted in Ref. [1] and we extend the same formalism to the baryon sector, focusing on the $Δ (1232) \to π N$ strong decay width because all hadrons involved in the reaction are very well established, the two hadrons in the final state are stable, avoiding further analysis, all quarks are light and so equivalent, and the decay width of the process is relatively well measured. Taking advantage of a Gaussian expansion method for the hadron's radial wave functions, the expression of the invariant matrix element can be related with the mean-square radii of hadrons involved in the decay. We use their experimental measures in such a way that only the strength of the quark-antiquark pair creation from the vacuum is a free parameter. This is then taken from our previous study of strong decay widths in the meson sector, obtaining a quite compatible result with experiment for the calculated $Δ (1232) \to π N$ decay width.
↳ hep-phhep-exhep-latnucl-ex+1CPC(2025)·1 citation
11
Femtoscopy can tell whether $Z_{c} (3900)$ and $Z_{cs} (3985)$ are resonances or virtual states
Zhi-Wei Liu🇨🇳 · Jun-Xu Lu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳
There have been extended and heated discussions on the nature of the two exotic states, $Z_{c} (3900)$ and $Z_{cs} (3985)$ , particularly whether they are near-threshold resonances, virtual states, or bound states. In this work, we demonstrate for the first time that the femtoscopic technique can be employed to distinguish between these three scenarios. More concretely, based on the Koonin-Pratt formula with a Gaussian source, we show that the low-momentum $D^{0} D^{*-}$ / $D^{0} D_{s}^{*-}$ correlation functions significantly differ in the three scenarios. The high-momentum results exhibit distinct characteristics in the resonant and virtual state scenarios, especially in small collision systems of 1 fm, as produced in $pp$ collisions at the LHC. We hope that these discoveries will stimulate further experimental studies and help clarify the nature of the many exotic states that have been discovered.
↳ hep-phhep-exnucl-exnucl-thSci.Bull.(2025)·36 citations
12
Mass Spectra of $Ξ$ and $Ω$ Baryons using hypercentral Constituent Quark Model
Chandni Menapara🇮🇳 · Ajay Kumar Rai🇮🇳
Hadron spectroscopy is an important tool towards the study of internal quark dynamics in a composite system. The present article focuses on the study of resonance spectra of strange baryons with S=-2, -3. The non-relativistic approach utilizes screened potential as hypercentral one to obtain masses. The spin-dependent part for all possible hyperfine states has been incorporated.
↳ hep-phnucl-thNuovo Cim.C(2024)·2 citations
13
Computing Scattering Cross Sections For Spherically Symmetric Potentials
Anil Khachi
This paper introduces students and instructors to the use of Scilab for calculating phase shifts from phenomenological potentials in nuclear, atomic, and molecular scattering, beginning with a Riccati-type nonlinear differential equation derived from the time-independent Schr $o ¨$ dinger equation. For spherically symmetric potentials, this equation can be easily solved using Xcos, a Scilab toolbox. \cite{PRC}\cite{bobby} Scilab is open source software that is used for numerical computations and can be freely downloaded for Windows, Linux and Mac OS.\cite{scilab} Xcos is a Scilab toolbox dedicated to the modeling and simulation of hybrid dynamic systems \cite{rachna}. Xcos provides users with the ability to model complex dynamical systems using a block diagram editor (GUI based), offering a step-by-step procedure for learning to solve complex differential equations interactively.
↳ physics.ed-phnucl-thAm.J.Phys.(2024)·1 citation
14
Diffusion coefficient matrix for multiple conserved charges: a Kubo approach
Sourav Dey🇮🇳 · Amaresh Jaiswal🇮🇳 · Hiranmaya Mishra🇮🇳
The strongly interacting matter created in relativistic heavy-ion collisions possesses several conserved quantum numbers, such as baryon number, strangeness, and electric charge. The diffusion process of these charges can be characterized by a diffusion matrix that describes the mutual influence of the diffusion of various charges. We derive the Kubo relations for evaluating diffusion coefficients as elements of a diffusion matrix. We further demonstrate that in the weak coupling limit, the diffusion matrix elements obtained through Kubo relations reduce to those obtained from kinetic theory with an appropriate identification of the relaxation times. We illustrate this evaluation in a toy model of two interacting scalar fields with two conserved charges.
↳ hep-phhep-thnucl-thJHEP(2024)·10 citations
15
An unconventional deformation of the nonrelativistic spin-1/2 Fermi gas
Vimal Palanivelrajan · Joaquín E. Drut
We explore a generalization of nonrelativistic fermionic statistics that interpolates between bosons and fermions, in which up to $K$ particles may occupy a single-particle state. We show that it can be mapped exactly to $K$ flavors of fermions with imaginary polarization. In particular, for $K = 2$ , we use such a mapping to derive the virial coefficients and relate them to those of conventional spin-1/2 fermions in an exact fashion. We also use the mapping to derive next-to-leading-order perturbative results for the pressure equation of state. Our results indicate that the $K = 2$ particles are more strongly coupled than conventional spin- $1/2$ fermions, as measured by the interaction effects on the virial expansion and on the pressure equation of state. In the regime set by the unitary limit, the proposed $K = 2$ deformation represents a universal many-body system whose properties remain largely unknown. In particular, the system can be expected to become superfluid at a critical temperature $T_{c}$ higher than that of the unitary limit. We suggest it may be possible to realize this system experimentally by engineering a polarized coupling to an electrostatic potential. Finally, we show that the $K = 2$ system does not display a sign problem for determinantal Monte Carlo calculations, which indicates that $T_{c}$ can at least in principle be calculated with conventional methods.
↳ cond-mat.quant-gasnucl-th0 citations

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