In this work, we propose a method for quantifying the difference between nuclear parton distribution functions in different nuclei and parton distribution functions in free nucleons using relative entropy (also known as the Kullback-Leibler divergence), a measure widely employed in quantum information theory. By introducing certain constraints and the ''minimum relative entropy'' hypothesis, we can determine the shape of the structure function in the intermediate-$\textit{x}$ region, which is closely connected to the renowned EMC effect. For quark structure functions, our results are consistent with the latest global fits to experimental data. This agreement suggests that the relative entropy-based methodology may provide novel insights into nucleon structure, particularly in cases where experimental data and theoretical QCD constraints are limited, such as those relevant to gluon nPDFs. Therefore, we apply this methodology to gluon nPDFs, analyzing the results from two commonly used global fitting groups, EPPS21 and nNNPDF3.0. Our analysis suggests that the central values of EPPS21 align more closely with the ''minimum relative entropy'' hypothesis. This finding underscores the utility of the proposed method and provides a valuable reference for future global fits of nPDFs.

China

Shu-Man Hu

Ao-Sheng Xiong

Ji Xu

Fu-Sheng Yu

Ji-Xin Yu

An analysis of nuclear parton distribution function based on relative entropy * Supported in part by the National Natural Science Foundation of China (12335003), the Fundamental Research Funds for the Central Universities (lzujbky-2023-stlt01, lzujbky-2024-oy02, and lzujbky-2025-eyt01), and the Scientific Research Innovation Capability Support Project for Young Faculty (ZYGXQNJSKYCXNLZCXM-P2). Ji Xu is supported in part by the National Natural Science Foundation of China (12475098, 12105247)

Neutron-rich nuclei near the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> shell closure are vital for <italic>r</italic>-process nucleosynthesis but remain challenging to produce. Multinucleon transfer reactions offer a promising route. We investigate the role of shell effects in such processes by extending the CLIM-H model with a deformation-dependent mass formula and a scaling factor <italic>a</italic> that linearly adjusts the shell-correction strength. Calculations for 136Xe on 208Pb, 204Hg, and 208Hg targets reveal a dual role: shell effects enhance few-nucleon transfers near the entrance channel but strongly suppress fragments requiring the transfer of many nucleons, most severely for the doubly magic 208Pb. This suppression stems from the cumulative transfer probabilities and is aggravated by lower survival after deexcitation. Thus, optimal production of exotic <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> nuclei requires avoiding strongly shell-closed collision partners at <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math>, as exemplified by doubly magic 208Pb. We propose 238U + 204Hg at <italic>E</italic> <inf>c.m.</inf>&#8239;&#8771;&#8239;1.45 <italic>V<inf>B</inf></italic> as a superior system, predicting significantly enhanced yields.

F.C. Dai

P.W. Wen

C.J. Lin

J.J. Liu

X.X. Xu

K.L. Wang

Y.D. Chen

H.L. Yang

Role of shell effects on producing neutron-rich nuclei in the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> region via multinucleon transfer reactions

The mechanism of reactions with weakly-bound proton-rich nuclei at energies near the Coulomb barrier is a long-standing open question owing to the paucity of experimental data. In this study, a complete kinematics measurement was performed for the proton drip-line nucleus $^{17}$F interacting with $^{58}$Ni at four energies near the Coulomb barrier. Thanks to the powerful performance of the detector array, exhaustive information on the reaction channels, such as the differential cross sections for quasielastic scattering, exclusive and inclusive breakup, as well as for fusion-evaporation protons and alphas, was derived for the first time. The angular distributions of quasielastic scattering and exclusive breakup can be described reasonably well by the continuum-discretized coupled-channels calculations. The inclusive breakup was investigated using the three-body model proposed by Ichimura, Austern, and Vincent, and results indicate the non-elastic breakup is the dominant component. The total fusion cross sections were determined by the fusion-evaporation protons and alphas. Based on the measured exclusive breakup data, the analysis of the classical dynamical simulation code PLATYPUS demonstrates that the incomplete fusion plays a minor role. Moreover, compared with $^{16}$O+$^{58}$Ni, both the reaction and total fusion cross sections of $^{17}$F+$^{58}$Ni exhibit an enhancement in the sub-barrier energy region, which mainly arises from couplings to the continuum states. This work indicates that the information of full reaction channels is crucially important to comprehensively understand the reaction mechanisms of weakly bound nuclear systems.

L. Yang

Japan

H. Yamaguchi

United States

Jin Lei

Italy

M. Mazzocco

N.R. Ma

L.J. Sun

D.X. Wang

G.X. Zhang

K. Abe

South Korea

S.M. Cha

K.Y. Chae

United Kingdom

A. Diaz-Torres

Brazil

J.L. Ferreira

S. Hayakawa

H.M. Jia

D. Kahl

A. Kim

M.S. Kwag

M. La Commara

R. Navarro Pérez

C. Parascandolo

D. Pierroutsakou

J. Rangel

Y. Sakaguchi

C. Signorini

E. Strano

F. Yang

Y.Y. Yang

G.L. Zhang

F.P. Zhong

J. Lubian

Insight into the reaction dynamics of proton drip-line nuclear system F+ Ni at near-barrier energies

Angular distributions of quasielastic scattering and breakup of the neutron-rich halo nucleus $^{11}$Be on a $^{208}$Pb target at an incident energy of 140 MeV (about 3.5 times the Coulomb barrier) were measured at HIRFL-RIBLL. A strong suppression of the Coulomb nuclear interference peak is observed in the measured quasielastic scattering angular distribution. The result demonstrates for the first time the persistence of the strong breakup coupling effect reported so far for reaction systems involving neutron-halo nuclei at this relatively high incident energy. The measured quasielastic scattering cross sections are satisfactorily reproduced by continuum discretized coupled channel (CDCC) calculations as well as by the XCDCC calculations where the deformation of the $^{10}$Be core is taken into account. The angular and energy distributions of the $^{10}$Be fragments could also be well reproduced considering elastic breakup (CDCC and XCDCC) plus nonelastic breakup contributions, with the latter evaluated with the model by Ichimura, Austern and Vincent [1]. The comparison of the $^{10}$Be energy distributions with simple kinematical estimates evidence the presence of a significant post-acceleration effect which, in the (X)CDCC frameworks, is accounted for by continuum-continuum couplings.

F.F. Duan

K. Wang

Spain

A.M. Moro

V. Guimarães

D.Y. Pang

J.S. Wang

Z.Y. Sun

A. Di Pietro

X. Liu

G. Yang

J.B. Ma

P. Ma

S.W. Xu

Z. Bai

X.X. Sun

Q. Hu

J.L. Lou

H.X. Li

S.Y. Jin

H.J. Ong

Q. Liu

J.S. Yao

H.K. Qi

Y.H. Zhang

X.H. Zhou

Z.G. Hu

H.S. Xu

Scattering of the halo nucleus Be from a lead target at 3.5 times the Coulomb barrier energy

The existence of light sterile neutrinos is a long-standing question in particle physics. Several experimental “anomalies” might be explained by introducing eV mass scaled light sterile neutrinos. Many experiments are actively searching for such light sterile neutrinos through neutrino oscillation. For long baseline experiments, the matter effect should be treated carefully for precise calculation of the neutrino oscillation probabilities. However, this is usually time-consuming or analytically complex. In this manuscript, we adopt a Jacobi-like method to diagonalize the Hermitian Hamiltonian matrix and derive analytically simplified neutrino oscillation probabilities for 3 (active) + 1 (sterile)-neutrino mixing for a constant matter density. These approximations can reach a considerably high numerical accuracy while retaining their analytical simplicity and fast computing speed. This would be useful for current and future long baseline neutrino oscillation experiments.

Bao-Biao Yue

Wei Li

Jia-Jie Ling

Fan-Rong Xu

A compact analytical approximation for a light sterile neutrino oscillation in matter Jiajie Ling acknowledges the support from National Key R&D program of China (2018YFA0404103) and National Natural Science Foundation of China (11775315). F. Xu is supported partially by NSFC (11605076), as well as the FRFCU (Fundamental Research Funds for the Central Universities in China) (21616309)

The mass of $^{27}$P is expected to impact the X-ray burst (XRB) model predictions of burst light curves and the composition of the burst ashes, but large uncertainties and inconsistencies still exist in the reported $^{27}$P masses. We have used the β-decay spectroscopy of $^{27}$S to determine the most precise mass excess of $^{27}$P to date to be <math><mo>−</mo><mn>659</mn><mo>(</mo><mn>9</mn><mo>)</mo></math> keV, which is 63 keV (2.3σ) higher and a factor of 3 more precise than the value recommended in the 2016 Atomic Mass Evaluation. Based on the new $^{27}$P mass, the <math><mmultiscripts><mrow><mi>Si</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>26</mn></mrow></mmultiscripts><msup><mrow><mo>(</mo><mi>p</mi><mo>,</mo><mi>γ</mi><mo>)</mo></mrow><mrow><mn>27</mn></mrow></msup></math>P reaction rate and its uncertainty were recalculated using Monte Carlo techniques. We also estimated the previously unknown mass excess of $^{27}$S to be 17678(77) keV, based on the measured β-delayed two-proton energy and the Coulomb displacement energy relations. The impact of these well-constrained masses and reaction rates on the modeling of the explosive astrophysical scenarios has been investigated by post-processing XRB and hydrodynamic nova models. Compared to the model calculations based on the masses and rates from databases, the abundance of <math><mi>A</mi><mo>=</mo><mn>26</mn></math> in the burst ashes is increased by a factor of 2.4, while no substantial change was found in the XRB energy generation rate or the light curve. Our calculation also suggests that $^{27}$S is not a significant waiting point in the rapid proton capture process, and the change of the <math><mmultiscripts><mrow><mi>Si</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>26</mn></mrow></mmultiscripts><msup><mrow><mo>(</mo><mi>p</mi><mo>,</mo><mi>γ</mi><mo>)</mo></mrow><mrow><mn>27</mn></mrow></msup></math>P reaction rate is not sufficiently large to affect the conclusion previously drawn on the nova contribution to the synthesis of galactic $^{26}$Al.

Hong Kong

S.Q. Hou

J. José

J. Lee

J.J. He

Z.H. Li

C.X. Yuan

Canada

F. Herwig

J. Keegans

T. Budner

H.Y. Wu

P.F. Liang

Y.H. Lam

Z.H. Gao

J.G. Wang

C.G. Wu

D.W. Luo

Y. Jiang

Y. Liu

D.S. Hou

R. Li

W.H. Ma

G.Z. Shi

G.M. Yu

D. Patel

Y.F. Wang

Y.C. Yu

Q.W. Zhou

P. Wang

L.Y. Hu

X. Wang

H.L. Zang

P.J. Li

Q.Q. Zhao

M. Pan

X.Y. Wang

R.F. Chen

M.L. Liu

W.Q. Yang

Y.M. Zhao

Experimentally well-constrained masses of P and S: Implications for studies of explosive binary systems

The decay of $^{218}$Pa was investigated by means of α and γ spectroscopy. The nucleus was produced in the fusion reaction $^{40}$Ar+$^{182}$W and separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). The known α decays of $^{218}$Pa were measured with improved precision and newly assigned to be originating from the ground state, which clarified the ambiguities in their previous assignments. In addition, a new isomeric state in $^{218}$Pa decaying with α-particle energies of 9691(15) keV, 9595(21) keV and a half-life of <math><msubsup><mrow><mn>135</mn></mrow><mrow><mo>−</mo><mn>32</mn></mrow><mrow><mo>+</mo><mn>62</mn></mrow></msubsup></math> μs was identified. The spins and parities of the involved states were tentatively assigned on the basis of the systematic α-decay properties of the odd-proton <math><mi>N</mi><mo>=</mo><mn>127</mn></math> isotones and shell model calculations.

M.M. Zhang

H.B. Yang

Z.G. Gan

Z.Y. Zhang

M.H. Huang

L. Ma

C.L. Yang

Y.S. Wang

Y.L. Tian

H.B. Zhou

S. Huang

X.T. He

S.Y. Wang

W.Z. Xu

H.W. Li

H.R. Yang

L.M. Duan

S.G. Zhou

Z.Z. Ren

JINR

A.A. Voinov

Yu.S. Tsyganov

A.N. Polyakov

M.V. Shumeiko

A new isomeric state in Pa

The β-delayed two-proton emission from $^{22}$Al was investigated experimentally through the implantation-decay method. A β-delayed two-proton decay branch from $^{22}$Al were identified based on the coincidence of the charged particles and γ-ray signals. The relative momentum (<math><msub><mrow><mi>q</mi></mrow><mrow><mi>p</mi><mi>p</mi></mrow></msub></math>) and the opening angle (<math><msub><mrow><mi>θ</mi></mrow><mrow><mi>p</mi><mi>p</mi></mrow></msub></math>) distributions of the two β-delayed protons are measured and a strong peak at <math><msub><mrow><mi>q</mi></mrow><mrow><mi>p</mi><mi>p</mi></mrow></msub><mo>∼</mo><mn>20</mn><mspace width="0.25em"></mspace><mtext>MeV/c</mtext></math>, as well as a peak at <math><msub><mrow><mi>θ</mi></mrow><mrow><mi>p</mi><mi>p</mi></mrow></msub><mo>∼</mo><msup><mrow><mn>30</mn></mrow><mrow><mo>∘</mo></mrow></msup></math> are observed clearly. The β-delayed $^{2}$He emission from $^{22}$Al with a probability of 29 (13)% by fitting the experimental data with the results of Monte Carlo simulations.

Y.T. Wang

D.Q. Fang

P.F. Bao

X.G. Cao

Z.T. Dai

B. Ding

W.B. He

M.R. Huang

S.L. Jin

M. Lv

L.X. Liu

Y. Li

S.T. Wang

H.W. Wang

S.Q. Ye

C.L. Zhou

M.H. Zhao

H.Q. Zhang

Y.G. Ma

W.Q. Shen

Observation of -delayed He emission from the proton-rich nucleus Al

The decay of the lightest nucleus with Tz=−3 , 22 Si, was studied by a silicon array. A charged-particle group at 5600 (70) keV in the decay-energy spectrum was identified experimentally as β -delayed two-proton emission from the isobaric analog state (IAS) of 22 Al. Experimental results of the IAS fed by a superallowed Fermi transition were compared with our large-scale shell-model calculations. The ground-state mass of 22 Si was obtained indirectly in the experiment for the first time. Two-proton separation energy for 22 Si is deduced to be −108 (125) keV, which indicates that it is a very marginal candidate for two-proton ground-state emission.

France

N.A. Smirnova

J. Li

C. Li

C.Z. Shi

M.W. Nie

X.F. Li

H. Li

Z.H. Liu

Y.J. Zhou

J. Chen

M. Wang

X.W. Ma

G.Q. Xiao

Observation of β -delayed two-proton emission in the decay of 22 Si

Considering the present limitation of the need for external parameters to describe the nucleus–nucleus potential and the couplings in the coupled-channels calculations, this work introduces an improved method without adjustable parameter to overcome the limitation and then sort out the positive Q -value neutron transfers (PQNT) effects based on the CCFULL calculations. The corresponding analysis for Ca+Ca , S,Ca+Sn , and S,Ca+Zr provides a reliable proof and a quantitative evaluation for the residual enhancement (RE) related to PQNT. In addition, the RE for S32,Ca40+Zr94 shows an unexpected larger enhancement than S32,Ca40+Zr96 despite the similar multi-neutron transfer Q -values. This method should rather strictly test the fusion models and be helpful for excavating the underlying physics.

A self-consistent method to analyze the effects of the positive Q -value neutron transfers on fusion