arXiv subjects

Jie Pu

Publications and source records attributed to Jie Pu.

18 recordsLinked to original sources

arXiv2026

Effects of light-cluster degrees of freedom on collective flows in heavy-ion collisions at FOPI energies

Within a lattice Boltzmann-Uehling-Uhlenbeck transport model coupled to a kinetic approach for light-cluster formation, we investigate the impact of explicit light-cluster degrees of freedom on collective flows in Au+Au collisions at FOPI energies with beam energies $E_{\rm beam}$= $120$--$1500 A$ MeV by using a density-, momentum-, and isospin-dependent N$5$LO Skyrme pseudopotential. We first benchmark the kinetic approach by comparing the calculated light-cluster yields with FOPI data in central Au+Au collisions. We then analyze the collective flows of protons and light nuclei (deuterons, tritons, $^{3}\mathrm{He}$, and $^{4}\mathrm{He}$) in mid-central collisions. For protons, calculations with and without dynamical light-cluster degrees of freedom are compared to quantify the influence of dynamical cluster formation on proton directed ($v_1$), elliptic ($v_2$), triangular ($v_3$), and quadrangular ($v_4$) flows. We find that the dynamical light-cluster effect appreciably modifies proton $v_1$--$v_4$ flows at $E_{\rm beam}=120$--$150 A$ MeV, remains visible at $E_{\rm beam}=250$--$400 A$ MeV, and gradually weakens at $E_{\rm beam}\gtrsim 600 A$ MeV. For light nuclei, the kinetic approach captures the overall beam-energy dependence of the FOPI flow data, with better agreement for $E_{\rm beam}\geq 400 A$ MeV. We further examine the nucleon-number scaling of $v_2/A$ in both model calculations and experimental data, finding that the kinetic light-cluster formation approach qualitatively reproduces the observed scaling behavior. These results highlight the importance of a dynamical treatment of light-cluster formation for interpreting collective flows in heavy-ion collisions below about $600 A$ MeV, although the clustering effects on proton flows are minor at higher collision energies.

nucl-th↗

arXiv2026

Evaluation of U-235 and U-238 Fission Product Yields Using Bayesian Neural Networks: Comparison of Baseline and Physics-Informed Models

U-235 and U-238 are fundamental materials in thermal and fast neutron breeding studies. Accurate evaluation of their fission product yields is of critical importance for advanced reactor design and nuclear waste management. In this work, a baseline Bayesian neural network model (BNN0) with two hidden layers of 20 neurons each was constructed. An improved model, BNN3, was developed by incorporating additional physics-informed features, namely the odd-even effect, beta-decay energy, and isospin, into the network inputs. Comparative analyses of the general distributions of the fission yields and isotopic chain structures demonstrate that BNN3 exhibits significantly improved reconstruction accuracy and consistency with the target cumulative fission-yield distributions. For 16 representative fission products, the energy-dependent yield predictions of BNN3 show better agreement with both experimental data and evaluated libraries, accompanied by noticeably narrower confidence intervals. These results indicate that the incorporation of relevant physical information improves the model's sensitivity to underlying fission mechanisms and enhances its capability to reproduce the systematic characteristics of cumulative fission-yield distributions. Together, these strategies contribute to more accurate and robust nuclear data modeling, providing a methodological foundation for the evaluation and development of next-generation nuclear data libraries.

nucl-th↗

arXiv2026

A unified classification-quantification framework for bubble-like nuclei within the extended quantum molecular dynamics model

A systematic study of relaxed low-energy cluster configurations for all nuclides listed in the AME2020 database is performed within the extended quantum molecular dynamics (EQMD) framework, with frictional cooling enabling stable relaxation. A unified classification-quantification framework based on the dimensionless parameters $BHTU$ is established to characterize bubble-like nuclear morphologies. The factor $B$, determined from the number of inflection points in the radial density profile, categorizes nuclei into droplet ($B=0$), bubble ($B=1$), and toroidal bubble ($B=2$). The parameter $H$ defines the degree of central density depletion, while $T$ and $U$ characterize the relative surface thickness and the relative size of the internal low-density region, respectively. Light nuclei are predominantly droplet-like with $B=0$, $H=0$, $T=1$, $U=0$. Most medium-mass nuclei have $B=1$, consistent with previous studies, especially in the vicinity of $^{40}$Ca and the neutron-rich region, where nuclei show a pronounced central hollowing with large $H$ and $U$ values, identifying them as prime candidates for experimental searches for bubble structures. Toroidal bubble nuclei ($B=2$), emerging for $Z\approx25$ and prevalent in heavy systems, display a local density minimum at intermediate radius together with a shell-like low-density region. Furthermore, bubble structures are found to be widespread in the superheavy region, in agreement with earlier studies. This parameter scheme not only reveals the morphological richness of nuclei but also establishes a predictive framework for exploring exotic nuclear shapes, thereby opening new avenues for future theoretical and experimental investigations.

nucl-th↗

arXiv2025

Anisotropic flows in Au+Au collisions at $\sqrt{s_{\rm{NN}}} = 2.4\,\text{GeV}$ with a Skyrme pseudopotential

Within the framework of the lattice Boltzmann-Uehling-Uhlenbeck transport model, we present a systematic study of proton anisotropic flow observables measured by the HADES collaboration, by utilizing the recently developed density-, momentum- and isospin-dependent N$5$LO Skyrme pseudopotential. In particular, we investigate the impacts of the momentum dependence of nucleon mean-field potentials, the stiffness of symmetric nuclear matter (SNM) EOS, the high-density behaviors of the symmetry energy and the in-medium modification of nucleon-nucleon elastic cross sections on proton $v_{1}$, $v_{2}$, $v_{3}$, and $v_{4}$ in Au+Au collisions at $\sqrt{s_{\rm{NN}}} = 2.4\,\text{GeV}$. Our results show that the proton anisotropic flows are strongly sensitive to the momentum dependence of nucleon mean-field potential as well as the incompressibility coefficient $K_0$ of SNM. In addition, the transverse momentum dependence of the proton $v_2$ exhibits a modest sensitivity to the higher-order skewness coefficient $J_0$ and kurtosis coefficient $I_0$ of SNM as well as the momentum dependence of the symmetry potential, while the transverse momentum dependence of the proton $v_1$ is shown to modestly depend on the in-medium modification of nucleon-nucleon elastic cross sections. Moreover, the high-density symmetry energy seems to have limited effects on the proton anisotropic flows. These findings highlight the necessity of considering the momentum dependence of nucleon mean-field potentials including the symmetry potential, the higher-order characteristic parameters of SNM EOS beyond $K_0$, and the in-medium modification of nucleon-nucleon elastic cross sections, in future Bayesian transport model analyses on proton anisotropic flows in heavy-ion collisions at HADES energies, thereby to extract information on nuclear matter EOS as well as the associated underlying nuclear effective interactions.

nucl-th↗

arXiv2025

Effects of mean-field momentum dependence on pion production in intermediate-energy heavy-ion collisions

Pion production in heavy-ion collisions at intermediate energies provides an important probe of the collision dynamics and nuclear matter equation of state, especially the high-density behavior of the symmetry energy. Using the lattice Boltzmann-Uehling-Uhlenbeck transport model with a recently developed nuclear effective interaction based on the so-called N$5$LO Skyrme pseudopotential, we investigate the effects of the momentum dependence of nucleon mean-field potentials on the pion production in Au+Au collisions at a beam energy of $1.23$~GeV/nucleon. We find that a stronger momentum dependence, for which the nucleon mean-field potentials increase faster with momentum, generally suppresses pion production. This feature can be understood in terms of the mean-field-induced modification of nucleon high-momentum phase space during the compression stage: a stronger momentum dependence can reduce the relative fraction of high-momentum nucleons in heavy-ion collisions, thereby suppressing the production of $\Delta$ resonances and pions.

nucl-th↗

arXiv2025

Inertia indices of signed graphs with given cyclomatic number and given number of pendant vertices

Let $\Gamma=(G, \sigma)$ be a signed graph of order $n$ with underlying graph $G$ and a sign function $\sigma: E(G)\rightarrow \{+, -\}$. Denoted by $i_+(\Gamma)$, $\theta(\Gamma)$ and $p(\Gamma)$ the positive inertia index, the cyclomatic number and the number of pendant vertices of $\Gamma$, respectively. In this article, we prove that $i_+(\Gamma)$, $\theta(\Gamma)$ and $p(\Gamma)$ are related by the inequality $i_+(\Gamma)\geq \frac{n-p(\Gamma)}{2}-\theta(\Gamma)$. Furthermore, we completely characterize the signed graph $\Gamma$ for which $i_+(\Gamma)=\frac{n-p(\Gamma)}{2}-\theta(\Gamma)$. As a by-product, the inequalities $i_-(\Gamma)\geq \frac{n-p(\Gamma)}{2}-\theta(\Gamma)$ and $\eta(\Gamma)\leq p(\Gamma)+2\theta(\Gamma)$ are also obtained, respectively.

math.SP↗

arXiv2025

Improved ion bunch quality of conical target irradiated by ultra-intense and ultra-short laser

We conduct particle-in-cell simulations to estimate the effects of circularly and linearly polarized SEL 100 PW lasers on flat Th targets with thicknesses of 50 nm, 100 nm and 250 nm, as well as easy to manufacture conical Th targets with angularity either on the left or right. As the thickness of the three types of targets increases and under the same polarized laser, the average energy, maximum energy and energy conversion efficiency of Th ions decrease as it is well-known, and except for the circularly polarized laser hit on the conical target with angularity on the left, the Th ion beam emittance also decreases, while its beam intensity increases conversely. The linearly polarized laser, compared to the circularly polarized laser with the same laser intensity, exhibits higher beam intensity, beam emittance and energy conversion efficiency for the same type and thickness of Th target. The conical Th target with angularity on the left and intermediate thickness, compared to the flat target and conical target with angularity on the right of the same thickness, possesses both higher ion average energy up to 7 GeV and virtually the same beam intensity up to 0.8 MA under the linearly polarized laser. The results lead us to an easier way of controlling laser-accelerated high-quality heavy ion beam by switching to an optimal laser-target configuration scheme, which may enable the synthesis of superheavy nuclei in a high-temperature and high-density extreme plasma environment in astronuclear physics.

physics.plasm-ph↗

arXiv2025

Atmospheric Antideuteron Flux Within a Dynamical Coalescence Approach

Cosmic antideuterons are considered as one of the most promising tools for the indirect detection of dark matter due to their ultra-low astrophysical backgrounds. Currently only upper limits on the antideuteron flux exist, but advancements in experimental detection technology may soon lead to positive signals. A major source of background is the production of secondary antideuterons through collisions of cosmic rays with the surrounding medium. In this study, antideuteron production is modeled using a multiphase transport model (AMPT) coupled with a dynamical coalescence model. By applying a widely used leaky box model and incorporating specific processes, we present a new theoretical baseline for atmospheric secondary antideuteron flux, including a tertiary contribution, from primary cosmic rays interacting with Earth's atmosphere. Our results indicate that the atmospheric antideuteron flux are within the range of various existing calculations and remain well below the upper limits set by the Balloon-borne Experiment with a Superconducting Spectrometer (BESS). The atmospheric antideuteron is found to dominate the antideuteron background at kinetic energies below $0.26 $ GeV/n.

nucl-th↗

arXiv2024

Probing the internal structures of $p\Omega$ and $\Omega\Omega$ with their production at the LHC

The strange dibaryons $p\Omega$ ($^5\rm{S}_2$) and $\Omega\Omega$ ($^1\rm{S}_0$) are likely bound, existing either in molecular states like the deuteron or as more exotic compact six-quark states. Here, we investigate the production of these two dibaryons in Pb+Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV at the CERN Large Hadron Collider (LHC) within a covariant coalescence model, which employs a blast-wave-like parametrization for the phase-space configurations of constituent particles at freeze-out. For the molecular states, the $p\Omega$ and $\Omega\Omega$ are produced via $p$-$\Omega$ and $\Omega$-$\Omega$ coalescence, respectively, while for the six-quark states, they are formed through $uudsss$ and $ssssss$ coalescence. We find that the yield ratio $N_{p\Omega}/N_{\Omega}$ and $N_{\Omega\Omega}/N_{\Omega}$ have a distinct centrality dependence between the molecular and multi-quark states, thus offering a promising way for distinguishing the two states. Our results suggest that the measurements of $p\Omega$ and $\Omega\Omega$ production in relativistic heavy-ion collisions can shed light on their internal structures.

hep-ph↗

arXiv2023

Study Duration Prediction for Clinical Trials with Time-to-Event Endpoints Using Mixture Distributions Accounting for Heterogeneous Population

In the era of precision medicine, more and more clinical trials are now driven or guided by biomarkers, which are patient characteristics objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or pharmacologic responses to therapeutic interventions. With the overarching objective to optimize and personalize disease management, biomarker-guided clinical trials increase the efficiency by appropriately utilizing prognostic or predictive biomarkers in the design. However, the efficiency gain is often not quantitatively compared to the traditional all-comers design, in which a faster enrollment rate is expected (e.g. due to no restriction to biomarker positive patients) potentially leading to a shorter duration. To accurately predict biomarker-guided trial duration, we propose a general framework using mixture distributions accounting for heterogeneous population. Extensive simulations are performed to evaluate the impact of heterogeneous population and the dynamics of biomarker characteristics and disease on the study duration. Several influential parameters including median survival time, enrollment rate, biomarker prevalence and effect size are identitied. Re-assessments of two publicly available trials are conducted to empirically validate the prediction accuracy and to demonstrate the practical utility. The R package \emph{detest} is developed to implement the proposed method and is publicly available on CRAN.

stat.ME↗

arXiv2023

Multi-stage Large Language Model Correction for Speech Recognition

In this paper, we investigate the usage of large language models (LLMs) to improve the performance of competitive speech recognition systems. Different from previous LLM-based ASR error correction methods, we propose a novel multi-stage approach that utilizes uncertainty estimation of ASR outputs and reasoning capability of LLMs. Specifically, the proposed approach has two stages: the first stage is about ASR uncertainty estimation and exploits N-best list hypotheses to identify less reliable transcriptions; The second stage works on these identified transcriptions and performs LLM-based corrections. This correction task is formulated as a multi-step rule-based LLM reasoning process, which uses explicitly written rules in prompts to decompose the task into concrete reasoning steps. Our experimental results demonstrate the effectiveness of the proposed method by showing 10% ~ 20% relative improvement in WER over competitive ASR systems -- across multiple test domains and in zero-shot settings.

cs.CL↗

arXiv2022

Building Synthetic Speaker Profiles in Text-to-Speech Systems

The diversity of speaker profiles in multi-speaker TTS systems is a crucial aspect of its performance, as it measures how many different speaker profiles TTS systems could possibly synthesize. However, this important aspect is often overlooked when building multi-speaker TTS systems and there is no established framework to evaluate this diversity. The reason behind is that most multi-speaker TTS systems are limited to generate speech signals with the same speaker profiles as its training data. They often use discrete speaker embedding vectors which have a one-to-one correspondence with individual speakers. This correspondence limits TTS systems and hinders their capability of generating unseen speaker profiles that did not appear during training. In this paper, we aim to build multi-speaker TTS systems that have a greater variety of speaker profiles and can generate new synthetic speaker profiles that are different from training data. To this end, we propose to use generative models with a triplet loss and a specific shuffle mechanism. In our experiments, the effectiveness and advantages of the proposed method have been demonstrated in terms of both the distinctiveness and intelligibility of synthesized speech signals.

eess.AS↗

arXiv2022

Determination of neutron-skin thickness using configurational information entropy

Configurational information entropy (CIE) theory was employed to determine the neutron skin thickness of neutron-rich calcium isotopes. The nuclear density distributions and fragment cross-sections in 350 MeV/u $^{40-60}$Ca + $^{9}$Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model. CIE quantities were determined from the nuclear density, isotopic, mass, and charge distributions. The linear correlations between the CIE determined using the isotopic, mass, and charge distributions and the neutron skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron skin thickness of neutron-rich nuclei.

nucl-th↗

arXiv2021

Bayesian evaluation of residual production cross sections in proton induced spallation reactions

The Bayesian neural network (BNN) method is used to construct a predictive model for fragment prediction of proton induced spallation reactions with the guidance of a simplified EPAX formula. Compared to the experimental data, it is found that the BNN + sEPAX model can reasonably extrapolate with less information compared with BNN method. The BNN + sEPAX method provides a new approach to predict the energy-dependent residual cross sections produced in proton-induced spallation reactions from tens of MeV/u up to several GeV/u.

nucl-th↗

arXiv2020

A Bayesian-Neural-Network Prediction for Fragment Production in Proton Induced Spallation Reaction

Fragments productions in spallation reactions are key infrastructure data for various applications. Based on the empirical parameterizations {\sc spacs}, a Bayesian-neural-network (BNN) approach is established to predict the fragment cross sections in the proton induced spallation reactions. A systematic investigation have been performed for the measured proton induced spallation reactions of systems ranging from the intermediate to the heavy nuclei and the incident energy ranging from 168 MeV/u to 1500 MeV/u. By learning the residuals between the experimental measurements and the {\sc spacs} predictions, the BNN predicted results are in good agreement with the measured results. The established method is suggested to benefit the related researches in the nuclear astrophysics, nuclear radioactive beam source, accelerator driven systems, and proton therapy, etc.

nucl-th↗

arXiv2018

Extracting strange quark freeze-out information in Pb+Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV from $ϕ$ and $Ω$ production

Using a covariant quark coalescence model combined with a blast-wave-like analytical parametrization for (anti-)strange quark phase-space freeze-out configuration, we extract information on strange quark freeze-out dynamics in Pb+Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV by fitting the measured transverse momentum spectra and elliptic flows ($v_2$) of $ϕ$ mesons and $Ω$ baryons. We find that although both the measured and calculated $v_2$ of $ϕ$ and $Ω$ satisfy the number-of-constituent-quark (NCQ) scaling, the NCQ-scaled $v_2$ is significantly smaller than the $v_2$ of strange quarks, implying that the NCQ-scaled $v_2$ of $ϕ$ and $Ω$ cannot be simply identified as the $v_2$ of strange quarks at hadronization. Meanwhile, our results indicate that the covariant quark coalescence model can nicely describe the spectra and elliptic flows of $ϕ$ and $Ω$ simultaneously, suggesting the coalescence mechanism is still valid for $ϕ$ and $Ω$ production in Pb+Pb collisions at LHC energies.

nucl-th↗

arXiv2018

Light nuclei production as a probe of the QCD phase diagram

It is generally believed that the quark-hadron transition at small values of baryon chemical potentials $μ_B$ is a crossover but changes to a first-order phase transition with an associated critical endpoint (CEP) as $μ_B$ increases. Such a $μ_B$-dependent quark-hadron transition is expected to result in a double-peak structure in the collision energy dependence of the baryon density fluctuation in heavy-ion collisions with one at lower energy due to the spinodal instability during the first-order phase transition and another at higher energy due to the critical fluctuations in the vicinity of the CEP. By analyzing the data on the $p$, d and $^3$H yields in central heavy-ion collisions within the coalescence model for light nuclei production, we find that the relative neutron density fluctuation $Δρ_n=\langle(δρ_n)^2\rangle/\langle ρ_n\rangle^2$ at kinetic freeze-out indeed displays a clear peak at $\sqrt{s_{NN}}=8.8$ GeV and a possible strong re-enhancement at $\sqrt{s_{NN}}=4.86$ GeV. Our findings thus provide a strong support for the existence of a first-order phase transition at large $μ_B$ and its critical endpoint at a smaller $μ_B$ in the temperature versus baryon chemical potential plane of the QCD phase diagram.

nucl-th↗

arXiv2017

Nuclear matter fourth-order symmetry energy in non-relativistic mean-field models

Based on systematic analyses of several popular non-relativistic energy density functionals with mean-field approximation, we estimate the value of the fourth-order symmetry energy $E_{\text{sym,4}}(ρ)$ at nuclear normal density $ρ_0$ and its density dependence, and explore the correlation between $E_{\text{sym,4}}(ρ_0)$ and other macroscopic quantities of nuclear matter properties. We use the empirical values of some nuclear macroscopic quantities to construct model parameter sets by Monte Carlo method for the conventional Skyrme-Hartree-Fock (SHF) model, the extended Skyrme-Hartree-Fock (eSHF) model, the Gogny-Hartree-Fock (GHF) model, and the momentum-dependent interaction (MDI) model. The value of $E_{\text{sym,4}}(ρ_0)$ is estimated to be $1.02\pm0.49$ MeV for the SHF model, $1.02\pm0.50$ MeV for the eSHF model, $0.70\pm0.60$ MeV for the GHF model, and $0.74\pm0.63$ MeV for the MDI model. Moreover, our results indicate that the density dependence of $E_{\text{sym,4}}(ρ)$ is model dependent, especially at higher densities. Furthermore, we find that the $E_{\text{sym},4}(ρ_0)$ has strong positive (negative) correlation with isoscalar (isovector) nucleon effective mass $m_{s,0}^*$ ($m_{v,0}^*$) at $ρ_0$. In particular, for the SHF and eSHF models, the $E_{\text{sym,4}}(ρ)$ is completely determined by the isoscalar and isovector nucleon effective masses $m_{s}^*(ρ)$ and $m_{v}^*(ρ)$, and the analytical expression is given. In the mean-field models, the magnitude of $ E_{\text{sym,4}}(ρ_0)$ is generally less than $2$ MeV, and its density dependence depends on models, especially at higher densities. $ E_{\text{sym,4}}(ρ_0)$ is strongly correlated with $m_{s,0}^*$ and $m_{v,0}^*$.

nucl-th↗