Neutron-rich nuclei around <sup>78</sup>Ni provide an important testing ground for the <math altimg='si2.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>50</mn></mrow></math> shell closure and cross-shell correlations. We develop a nuclear-structure implementation of the semistochastic heat-bath configuration interaction (SHCI) method and apply it, for the first time, to nuclear structure calculations with <italic>ab initio</italic> valence-space Hamiltonians. SHCI builds a compact variational space through heat-bath selection and accounts for remaining correlations using semistochastic second-order perturbation theory. Combined with valence-space in-medium similarity renormalization group Hamiltonians derived from chiral two- and three-nucleon interactions, SHCI provides a large-space solver for extended proton- <italic>pf</italic> and neutron- <italic>gds</italic> valence spaces beyond conventional exact diagonalization. Benchmark calculations for <sup>78</sup>Ni show that SHCI achieves faster convergence of low-lying spectra than comparable particle-hole truncations, demonstrating the efficiency of determinant-based selection. We further study the <math altimg='si2.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>50</mn></mrow></math> isotones and the Ni, Cu, and Zn isotopic chains toward the predicted neutron-rich limits. The results indicate a robust but gradually weakened <math altimg='si2.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>50</mn></mrow></math> shell closure from Ni to Zn, predict the drip-line nuclei, and suggest a possible weak subshell structure near <math altimg='si4.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>58</mn></mrow></math>. This work establishes SHCI as a systematically improvable large-space solver for <italic>ab initio</italic> nuclear structure.

China

P.Y. Wang

K.H. Li

Q. Yuan

W.J. Huang

J.G. Li

Semistochastic heat-bath configuration interaction with <italic>ab initio</italic> valence-space Hamiltonians for neutron-rich Ni, Cu, and Zn isotopes

In this work, we investigate three representative new-physics resonances that couple to Standard Model (SM) quarks through flavor-changing interactions involving the top quark. We identify the possible SMEFT operators at the electroweak scale and analyze their phenomenology.

Min Huang

Yandong Liu

Hao Zhang

Exploring new resonances with direct top flavor changing interactions * Min Huang and Hao Zhang is supported in part by the National Science Foundation of China (12575114, 12235001, 12075257)

We study the equation of state (EoS) of QCD matter in a bottom-up holographic setup that combines an Einstein-Maxwell-dilaton (EMD) sector with an improved Karch-Katz-Son-Stephanov (KKSS) flavor action. In the probe approximation, we perform an inverse reconstruction of the model functions by parameterizing them with neural networks and solving the EMD equations via a differentiable ODE solver (a neural ODE framework), calibrating the model to a reference thermodynamic table for $(2+1)$ -flavor QCD at finite temperature and finite baryon chemical potential. The reconstructed model functions are then parameterized and kept fixed across thermodynamic states. Next, viewing the EMD sector as an effective description of pure Yang-Mills theory, we fix its parameters by fitting the $\mu_B=0$ lattice pure-glue EoS using a hybrid optimization strategy. Finally, we go beyond the probe limit and solve the coupled EMD+KKSS equations with back-reaction, using the pure-glue-calibrated EMD sector as a fixed input and varying the KKSS couplings to compare with the $\mu_B=0$ two-flavor lattice EoS. We find a visible mismatch and a high-temperature behavior in which the back-reacted dimensionless ratios approach a nearly $\beta_1$ -insensitive plateau close to the pure-glue baseline, providing a simple structural diagnostic for the present flavor-sector truncation.

Yutian Deng

Mei Huang

Lin Zhang

Holographic QCD equation of state constrained by lattice QCD: neural-ODE for probe-limit and a back-reaction test * Start-up funding from Sun Yat-sen University (SYSU) (Y. Deng and L. Zhang); National Natural Science Foundation of China (NSFC) (12235016) (L. Zhang and M. Huang) and 12221005 (M. Huang)

In this work, we investigate the resonance structures in the $ \Sigma(1/2^-) $ system from both three-quark and five-quark perspectives within the framework of the chiral quark model. An accurate few-body computational approach, the Gaussian expansion method, is employed to construct the orbital wave functions of multiquark states. To reduce the model dependence on parameters, we fit two sets of parameters to check the stability of the results. The calculations show that our results remain stable despite changes in the parameters. In the three-quark calculations, two $ \Sigma(1/2^-) $ states are obtained with energies around 1.8 GeV, which are good candidates for the experimentally observed $ \Sigma(1750) $ and $ \Sigma(1900) $ . In the five-quark configuration, several stable resonance states are identified, including $ \Sigma \pi $ , $ N \bar{K} $ , and $ N \bar{K}^{*} $ . These resonance states survive the channel-coupling calculations under the complex-scaling framework and manifest as stable structures. Our results support the existence of a two-pole structure for the $ \Sigma(1/2^-) $ system, predominantly composed of $ \Sigma \pi $ and $ N \bar{K} $ configurations, analogous to the well-known $ \Lambda(1380) $ - $ \Lambda(1405) $ ( $ \Sigma \pi $ - $ N \bar{K} $ ) system. On the other hand, although the energy of the $ N \bar{K}^{*} $ configuration is close to that of $ \Sigma(1750) $ and $ \Sigma(1900) $ , the obtained width is not consistent with the experimental values. This suggests that the $ N \bar{K}^{*} $ state needs to mix with three-quark components to better explain the experimental $ \Sigma(1750) $ and $ \Sigma(1900) $ states. According to our decay width calculations, the predicted two resonance states are primarily composed of $ \Sigma \pi $ and $ N \bar{K} $ , with their main decay channel being $ \Lambda \pi $ . Therefore, we encourage experimental groups to search for the predicted two-pole structure of the $ \Sigma(1/2^-) $ system in the invariant mass spectrum of $ \Lambda \pi $ .

Yu Yao

Xuejie Liu

Xiaoyun Chen

Yuheng Wu

Jialun Ping

Yue Tan

Qi Huang

Investigation of resonances in the Σ(1/2$^{–}$) system based on the chiral quark model * Supported partly by the National Science Foundation of China (12205249, 12305087). Yue Tan is supported by the Funding for School-Level Research Projects of Yancheng Institute of Technology (xjr2022039) and the Qinglan Project Fund of Jiangsu Province. Qi Huang is supported by the Start-up Funds of Nanjing Normal University (184080H201B20)

Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of $^{82}$Zr and $^{84}$Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of $^{79}$Y, $^{81}$Zr, and $^{83}$Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr–Nb cycle in the rp-process unlikely. The new proton separation energy of $^{83}$Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus $^{84}$Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.

Germany

Y.M. Xing

K.A. Li

Y.H. Zhang

X.H. Zhou

M. Wang

Yu.A. Litvinov

K. Blaum

Japan

S. Wanajo

S. Kubono

G. Martínez-Pinedo

A. Sieverding

R.J. Chen

P. Shuai

C.Y. Fu

X.L. Yan

France

X. Xu

X.D. Tang

H.S. Xu

T. Bao

X.C. Chen

B.S. Gao

J.J. He

Y.H. Lam

H.F. Li

J.H. Liu

X.W. Ma

R.S. Mao

M. Si

M.Z. Sun

X.L. Tu

Q. Wang

J.C. Yang

Y.J. Yuan

Q. Zeng

P. Zhang

X. Zhou

W.L. Zhan

S. Litvinov

G. Audi

T. Uesaka

Y. Yamaguchi

T. Yamaguchi

A. Ozawa

United States

C. Fröhlich

United Kingdom

T. Rauscher

Switzerland

F.K. Thielemann

B.H. Sun

Y. Sun

A.C. Dai

F.R. Xu

Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on And Nucleosynthesis Processes

We improve the Monte-Carlo based QCD sum rules by introducing the rigorous Hölder-inequality-determined sum rule window and a Breit-Wigner type parametrization for the phenomenological spectral function. In this improved sum rule analysis methodology, the sum rule analysis window can be determined without any assumptions on OPE convergence or the QCD continuum. Therefore, an unbiased prediction can be obtained for the phenomenological parameters (the hadronic mass and width etc.). We test the new approach in the ρ meson channel with re-examination and inclusion of αs corrections to dimension-4 condensates in the OPE. We obtain results highly consistent with experimental values. We also discuss the possible extension of this method to some other channels.

Qi-Nan Wang

Canada

Zhu-Feng Zhang

T.G. Steele

Hong-Ying Jin

Zhuo-Ran Huang

A comprehensive revisit of the ρ meson with improved Monte-Carlo based QCD sum rulesSupported by NSFC (11175153, 11205093, 11347020), Open Foundation of the Most Important Subjects of Zhejiang Province, and K. C. Wong Magna Fund in Ningbo University, TGS is Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), Z. F. Zhang and Z. R. Huang are Grateful to the University of Saskatchewan for its Warm Hospitality