Nuclear Theory·nucl-th

Tuesday·July 9, 2024

15 papers—7 primary·8 cross-listed

01
[Submitted on 3 Jul 2024]
Magnetic structure of $A \leq 10$ nuclei using the Norfolk nuclear models with quantum Monte Carlo methods
G. Chambers-Wall🇺🇸 · A. Gnech🇺🇸 · G. B. King🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · R. Schiavilla🇺🇸 · R. B. Wiringa🇺🇸
We present Quantum Monte Carlo calculations of magnetic moments, form factors, and densities of $A \leq 10$ nuclei within a chiral effective field theory approach. We use the Norfolk two- and three-body chiral potentials and their consistent electromagnetic one- and two-nucleon current operators. We find that two-body contributions to the magnetic moment can be large (up to $\sim 33%$ in $A = 9$ systems). We study the model dependence of these observables and place particular emphasis on investigating their sensitivity to using different cutoffs to regulate the many-nucleon operators. Calculations of elastic magnetic form factors for $A \leq 10$ nuclei show excellent agreement with the data out to momentum transfers $q \approx 3$ fm $^{- 1}$ .
Comments:
25 pages, 14 figures, 6 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.04744 [pdf]
PRC(2024)·15 citations
02
[Submitted on 7 Jul 2024]
Statistical Production of $B_{c}$ Mesons in Heavy-Ion Collisions at the LHC Energy
Shouxing Zhao🇨🇳 · Min He🇨🇳
The recombination production of $B_{c}$ mesons in heavy-ion collisions at the LHC energy is facilitated by the abundant and highly thermalized charm ( $c$ ) quarks transported in the deconfined medium created. We study the production of $B_{c}$ mesons via $c$ and bottom ( $b$ ) quark recombination in a statistical fashion by placing $B_{c}$ in the position of a member of the family of open $b$ hadrons, which allows us to make quantitative predictions for the modifications of the production fraction ( $f_{c}$ ) of $B_{c}$ mesons and its relative production to $B$ mesons in $s_{NN} = 5.02$ TeV Pb-Pb collisions with respect to proton-proton ( $pp$ ) collisions at the same energy. The statistical production yield of $B_{c}$ mesons is converted into the transverse momentum ( $p_{T}$ ) distribution with the shape computed from resonance recombination using the $c$ - and $b$ -quark phase space distributions that have been simulated via Langevin diffusion and constrained by open $c$ - and $b$ -hadron observables. Supplemented with the component fragmented from $b$ -quark spectrum that dominates at high $p_{T}$ , the total $p_{T}$ spectrum of $B_{c}$ mesons is obtained and converted into the $p_{T}$ dependent nuclear modification factor ( $R_{AA}$ ). Both $f_{c}$ and the integrated $R_{AA}$ exhibit a $\sim 5$ -fold enhancement in central Pb-Pb collisions relative to the $pp$ reference. Comparison with data measured by the CMS experiment shows decent agreement within theoretical and experimental uncertainties.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2407.05234 [pdf]
PLB(2025)·6 citations
03
[Submitted on 7 Jul 2024]
Quantifying angular distributions in multinucleon transfer reactions with a semi-classical method
Zehong Liao · Zepeng Gao · Yu Yang · Yueping Fang · Jun Su · Long Zhu
The multinucleon transfer (MNT) process in low-energy heavy ion collisions can be utilized to produce unknown nuclei far beyond the stability line. However, the reaction products exhibit broad angular and energy distributions, which could lower the experimental detection efficiency. We present a classical approach that employs a parameterized angular distribution to describe the complex issue. By analyzing limited experimental data on angular distribution, we proposed a three-parameter formula to calculate the angular distribution and identified the dependencies of the parameters. We also discuss the sensitivity of these parameters within this method. A comprehensive comparison with microscopic models and experimental data across a wide range of conditions is conducted. The proposed formula offers an efficient and straightforward way to determine the angular distribution of MNT products.
Comments:
6 pages, 6 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.05395 [pdf]
PRC(2025)·3 citations
04
[Submitted on 8 Jul 2024]
Significance of tensor force in pseudo-spin symmetry
H. Nakada · T. Inakura
We point out that the pseudo-spin symmetry (PSS) of nuclei significantly depends on the proton ( $Z$ ) and neutron numbers ( $N$ ), sometimes giving rise to the characteristic structures. By using the non-relativistic spherical Hartree-Fock calculation with a realistic tensor force, we show that the tensor force may be deeply relevant to the $Z$ - and $N$ -dependence of the PSS. While the PSS has often been discussed in the context of the relativistic symmetry, the tensor-force effects on the PSS sometimes look analogous to the $Z$ -and $N$ -dependence of the PSS in the relativistic mean-field (RMF) calculations without explicit tensor force. The observed variation of the $p 0 d_{3/2}$ - $p 1 s_{1/2}$ levels from $^{40}$ Ca to $^{34}$ Si is consistent with the tensor-force-driven $Z$ -dependence of the PSS, but not necessarily with the RMF result. Even though it is too early to be conclusive, this result elucidates the significance of the tensor force when discussing the PSS.
Comments:
to appear in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.05524 [pdf]
PRC(2024)·5 citations
05
[Submitted on 8 Jul 2024]
Volume effect on the extraction of sound velocity in high-energy nucleus-nucleus collisions
Jing-An Sun🇨🇳 · Li Yan🇨🇳
The determination of the speed of sound in quark-gluon plasma is a crucial aspect of understanding the properties of strongly interacting matter created in relativistic heavy-ion collisions. In this study, we investigate the impact of initial-state fluctuations on the extraction of the speed of sound in a quark-gluon plasma in the ultra-central collisions. By employing the TRENTo model for simulating initial conditions, we demonstrate that these fluctuations lead to sizable volume effect, which in turn corrects the measured values of the sound velocity. With respect to realistic conditions of high-energy heavy-ion experiments, we provide quantitative estimate of these corrections.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2407.05570 [pdf]
PLB(2025)·9 citations
06
[Submitted on 8 Jul 2024]
Surface and curvature tensions of cold dense quark matter: a term-by-term analysis within the Nambu-Jona-Lasinio model
A. G. Grunfeld🇦🇷 · M. F. Izzo Villafañe🇦🇷 · G. Lugones🇧🇷
In this paper, we conduct a thorough investigation of the surface and curvature tensions, $σ$ and $γ$ , of three-flavor cold quark matter using the Nambu-Jona-Lasinio (NJL) model with vector interactions. Our approach ensures both local and global electric charge neutrality, as well as chemical equilibrium under weak interactions. By employing the multiple reflection expansion formalism to account for finite size effects, we explore the impact of specific input parameters, particularly the vector coupling constant ratio $η_{V}$ , the radius $R$ of quark matter droplets, as well as charge-per-baryon ratio $ξ$ of the finite size configurations. We focus on the role of the contributions of each term of the NJL Lagrangian to the surface and curvature tensions in the mean field approximation. We find that the total surface tension exhibits two different density regimes: it remains roughly constant at around $100 MeV f m^{- 2}$ up to approximately $2 - 4$ times the nuclear saturation density, and beyond this point, it becomes a steeply increasing function of $n_{B}$ . The total surface and curvature tensions are relatively insensitive to variations in $R$ but are affected by changes in $ξ$ and $η_{V}$ . We observe that the largest contribution to $σ$ and $γ$ comes from the regularized divergent term, making these quantities significantly higher than those obtained within the MIT bag model.
Comments:
12 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2407.05606 [pdf]
Universe(2025)·3 citations
07
[Submitted on 8 Jul 2024]
Magnetic dipole $γ$ -ray strength functions in the crossover from spherical to deformed neodymium isotopes
A. Mercenne · P. Fanto · W. Ryssens · Y. Alhassid
We calculate the magnetic dipole $γ$ -ray strength functions in a chain of even-mass neodymium isotopes $^{144 - 152}$ Nd in the framework of the configuration-interaction (CI) shell model. We infer the strength function by applying the maximum entropy method (MEM) to the exact imaginary-time response function calculated with the shell-model Monte Carlo (SMMC) method. The success of the MEM depends on the choice of a good strength function as a prior distribution. We investigate two choices for the prior strength function: the static path approximation (SPA) and the quasiparticle random-phase approximation (QRPA). We find that the QRPA is a better approximation at low temperatures (i.e., near the ground state), while the SPA is a better choice at finite temperatures. We identify a low-energy enhancement (LEE) in the MEM deexcitation $M 1$ strength functions of the even-mass neodymium isotopes and compare with recent experimental results for the total deexcitation $γ$ -ray strength functions. The LEE is already seen in the SPA strength function but not in the QRPA strength function, indicating the importance of large-amplitude static fluctuations around the mean field in reproducing the LEE. Our method is currently the only one which can reproduce LEE in heavy open-shell nuclei where conventional CI shell model calculations are prohibited. With the onset of deformation as number of neutrons increases along the chain of neodymium isotopes, we observe that some of the LEE strength transfers to a low-energy excitation, which we interpret as a finite-temperature "scissors" mode. We also observe a finite-temperature spin-flip mode.
Comments:
11 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.06161 [pdf]
PRC(2024)·5 citations
08
[Submitted on 5 Jul 2024] (cross-list from hep-ph)
Gluon to $q q ˉ$ antenna in anisotropic QCD matter: spin-polarized and azimuthal jet observables
João Barata🇺🇸 · Carlos A. Salgado🇪🇸 · João M. Silva🇪🇸
We study the production of a quark-antiquark antenna in the presence of a dense and anisotropic QCD medium. We assume the antenna to originate from an unpolarized gluon state, and consider both massless and massive final states. The medium anisotropy is captured by allowing the jet quenching coefficient to take different magnitudes in orthogonal directions with respect to the jet axis. We find that the final particle distribution is sensitive to the medium anisotropy, and more importantly, that this effect couples directly to the helicity/spin of the final states. We propose to look into these effects by performing a Fourier decomposition of the particle distribution inside the jet. In our medium model, we find that the spin independent terms contribute to the even harmonics of the cosine series. The helicity/spin dependence enters only through the sine Fourier series. We further explore the spin dependence by examining the degree of polarization of the final states in different directions. Our results indicate that the anisotropies present in the QCD matter produced in heavy ion collisions can be probed by studying azimuthal and spin observables inside jets.
Comments:
33 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2407.04774 [pdf]
JHEP(2024)·30 citations
09
[Submitted on 6 Jul 2024] (cross-list from hep-ph)
QCD Masterclass Lectures on Jet Physics and Machine Learning
Andrew J. Larkoski🇺🇸
These lectures were presented at the 2024 QCD Masterclass in Saint-Jacut-de-la-Mer, France. They introduce and review fundamental theorems and principles of machine learning within the context of collider particle physics, focused on application to jet identification and discrimination. Numerous examples of binary discrimination in jet physics are studied in detail, including $H \to b b ˉ$ identification in fixed-order perturbation theory, generic one-versus two-prong discrimination with parametric power counting techniques, and up versus down quark jet classification by assuming the central limit theorem, isospin conservation, and a convergent moment expansion of the single particle energy distribution. Quark versus gluon jet discrimination is considered in multiple contexts, from using additive, infrared and collinear safe observables, to using hadronic multiplicity, and to including measurements of the jet charge. While many of the results presented here are well known, some novel results are presented, the most prominent being a parametrized expression for the likelihood ratio of quark versus gluon discrimination for jets on which hadronic multiplicity and jet charge are simultaneously measured. End-of-lecture exercises are also provided.
Comments:
130 pages, 32 figures, 603 references; v2: fixed some minor typos, accepted to EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.04897 [pdf]
EPJC(2024)·20 citations
10
[Submitted on 7 Jul 2024] (cross-list from hep-ph)
Impact of finite volume on kaon, antikaon, and $ϕ$ meson masses and decay width in asymmetric strange hadronic matter
Zeeshan Ahmad🇮🇳 · Nisha Chahal🇮🇳 · Arvind Kumar🇮🇳 · Suneel Dutt🇮🇳
In the present work, we investigate the impact of finite volume on the in-medium properties of kaons ( $K^{+}$ , $K^{0}$ ) and antikaons ( $K^{-}$ , $K^{0} ˉ$ ), and $ϕ$ mesons in the isospin asymmetric strange hadronic medium at finite density and temperature. We use the chiral SU(3) hadronic mean-field model, which accounts for the interactions between baryons through the exchange of scalar ( $σ, ζ, δ$ ) and vector ( $ω$ , $ρ$ , $ϕ$ ) fields. To investigate the effects of finite volume, we apply the multiple reflection expansion (MRE) technique for calculations of the density of states. The non-strange scalar field $σ$ shows significant variation in an asymmetric medium, while the strange scalar field $ζ$ shows good dependency in the strange medium. We use the medium-modified masses of kaons and antikaons calculated using the chiral SU(3) model to obtain the masses and decay width of $ϕ$ mesons in finite volume hadronic medium. To obtain the masses and decay widths of $ϕ$ mesons, an effective Lagrangian approach with $ϕ$ $K$ $K ˉ$ interactions at one-loop level is used in the present work. We obtain the effective masses and decay widths in the finite volume matter, for the spherical geometry of the medium with Neumann and Dirichlet boundary conditions as well as for the cubic geometry. The finite volume effects are found to be appreciable at high baryon densities.
Comments:
40 pages and 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05263 [pdf]
PTEP(2025)·4 citations
11
[Submitted on 7 Jul 2024] (cross-list from hep-ph)
Pion photoproduction of nucleon excited states with Hamiltonian effective field theory
Yu Zhuge🇨🇳 · Zhan-Wei Liu🇨🇳 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺
We refine our previous calculation of multipole amplitude $E_{0 +}$ for pion photoproduction process, $γ N \to π N$ . The treatment of final-state interactions is based upon an earlier analysis of pion-nucleon scattering within Hamiltonian effective field theory, supplemented by incorporating contributions from the $N^{*} (1650)$ and the $K Λ$ coupled channel. The contribution from the bare state corresponding to the $N^{*} (1650)$ significantly enhances our results. Additionally, we also compute the multipole amplitude $M_{1 -}$ , which is of direct relevance to the Roper resonance. The results are comparable with other dynamical coupled channel models, even though the contribution from the bare state (interpreted as a 2 $s$ excitation) in this channel is small because of its large mass.
Comments:
14 pages, 9 figures, 3 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05334 [pdf]
PRD(2024)·14 citations
12
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Probing the nature of the anticharmed-strange pentaquark states: mass spectra, decays, and magnetic moments
Xuejie Liu🇨🇳 · Yue Tan🇨🇳 · Xiaoyun Chen🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳
Within the framework of the quark delocalization color screening model, a systematic investigation of the anticharmed-strange pentaquark system is performed using the resonance group method. The currently estimations predict three bound states with estimated masses to be 2886 MeV, 3039 MeV, and 3153 MeV, respectively. Additionally, three resonance states are identified in various scattering phase shifts processes. Among them, two resonance states $Σ D$ and $Σ^{*} D^{*}$ with quantum number $\frac{1}{2} (\frac{1}{2}^{-})$ are detected in channels $N D_{s}^{*}$ and $N D$ , and $Σ D^{*}$ and $Λ D$ , with masses and decay widths of ( $M_{R} = 3053 \sim 3055$ MeV, $T_{t o t a l} = 13.0 \sim 13.4$ MeV) and ( $M_{R} = 3389 \sim 3390$ MeV, $T_{t o t a l} = 10.4$ MeV), respectively. In the $Λ D^{*}$ and $Σ D^{*}$ channels, a resonance state with quantum number $\frac{1}{2} (\frac{3}{2}^{-})$ is discovered, with its mass and decay width being $3250 \sim 3252$ MeV and 4.4 MeV, respectively. These predicted pentaquark states have $c ˉ s nnn$ quark compositions, allowing them to be recognized as genuine pentaquark states. To validate these predictions, it is expected that upcoming experiments will further explore the predicted resonance and bound states in these possible decay channels.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05598 [pdf]
PRD(2024)·3 citations
13
[Submitted on 8 Jul 2024] (cross-list from nucl-ex)
Effect of ground-state deformation on the Isoscalar Giant Monopole Resonance and the first observation of overtones of the Isoscalar Giant Quadrupole Resonance in rare-earth Nd isotopes
M. Abdullah · S. Bagchi · M.N. Harakeh · H. Akimune · D. Das · T. Doi · L. M. Donaldson · Y. Fujikawa · M. Fujiwara · T. Furuno · U. Garg · Y.K. Gupta and 24 other authors
The strength distributions of the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in 142,146-150Nd have been determined via inelastic alpha-particle scattering with the Grand Raiden (GR) Spectrometer at the Research Center for Nuclear Physics (RCNP), Japan. In the deformed nuclei 146-150Nd, the ISGMR strength distributions exhibit a splitting into two components, while the nearly spherical nucleus 142Nd displays a single peak in the ISGMR strength distribution. A noteworthy achievement in this study is the first-time detection of overtones in the Isoscalar Giant Quadrupole Resonance (ISGQR) strength distributions within Nd isotopes at an excitation energy around 25 MeV obtained through Multipole Decomposition Analysis (MDA).
Comments:
Accepted for publication in Physics Letters B
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.05685 [pdf]
PLB(2024)·6 citations
14
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Studying the $Ξ (2030)$ as a predominantly $K ˉ^{*} Σ$ molecular state
Jing-wen Feng · Cai Cheng · Yin Huang
Since its discovery in 1977, the spin-parity of $Ξ (2030)$ has not been fully determined experimentally. The latest Particle Data Group (PDG) listing suggests it may be a baryon with $J = 5/2$ . Therefore, studying the mass spectrum and decay properties of $Ξ (2030)$ has become a current hot topic to definitively establish its spin-parity. As the three-quark model fails to explain $Ξ (2030)$ , we previously proposed it may be a molecule primarily composed of $K ˉ Σ$ with $J^{P} = 5/ 2^{+}$ , based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of $Ξ (2030)$ assuming it is a $P$ -wave $J^{P} = 5/ 2^{+}$ meson-baryon molecule predominantly composed of $K ˉ Σ$ . We calculated all experimentally measured two-body and three-body final state decay widths of $Ξ (2030)$ , including $Ξ (2030) \to K ˉ Λ, K ˉ Σ, π Ξ, π Ξ^{*}$ , and $Ξ (2030) \to π π Ξ, π K ˉ Σ, π K ˉ Λ$ . The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that $Ξ (2030)$ is a molecule with spin-parity $J^{P} = 5/ 2^{+}$ , predominantly composed of $K ˉ^{*} Σ$ . Compared to the experimental central values, our results are slightly smaller, which suggests that $Ξ (2030)$ may contain additional components besides meson-baryon molecular components, such as three quark structures.
Comments:
8 papers,6 figures,1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05697 [pdf]
0 citations
15
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Light nuclei photoproduction in relativistic heavy ion ultraperipheral collisions
Jin-Yu Hu🇨🇳 · Shuo Lin🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳
We have investigated light nuclei pair photoproduction in relativistic heavy ion ultraperipheral collisions. As a first attempt, we employ our previously developed quantum electrodynamics model, which incorporates a wave-packet description of initial nuclei, to compute the cross section for proton-antiproton pair photoproduction. The effective vertex for the photon and proton interaction is chosen based on studies of two-photon exchange effects in hadron physics. We present the transverse momentum, invariant mass, and azimuthal angle distributions of proton-antiproton pairs at $s_{N N} = 200$ GeV in Au+Au ultraperipheral collisions. We observe a $cos (2 ϕ)$ modulation and an almost negligible $cos (4 ϕ)$ modulation in the azimuthal angle distribution. Our studies helps us better understand the matter generated by light.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.06091 [pdf]
4 citations

Affiliations

first authorsco-authorsvia INSPIRE