Chinese Physics C

Highlights

New constraints on coherent elastic neutrino–nucleus scattering by the νGeN experiment
V. Belov, A. Bystryakov, M. Danilov, S. Evseev, M. Fomina, G. Ignatov, S. Kazartsev, J. Khushvaktov, T. Khussainov, A. Konovalov, A. Kuznetsov, A. Lubashevskiy, D. Medvedev, D. Ponomarev, D. Sautner, K. Shakhov, E. Shevchik, M. Shirchenko, S. Rozov, I. Rozova, S. Vasilyev, E. Yakushev, I. Zhitnikov, D. Zinatulina, (νGeN Collaboration)

2025, 49(5): 053004. doi: 10.1088/1674-1137/adb9c8

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The $ \nu $GeN experiment searches for coherent elastic neutrino-nucleus scattering (CE$ \nu $NS) at the Kalinin Nuclear Power Plant. A 1.41 kg high-purity low-threshold germanium detector surrounded by active and passive shielding is deployed at the minimal distance of 11.1 m allowed by the lifting mechanism from the center of the reactor core, utilizing one of the highest antineutrino fluxes among competing experiments. The direct comparison of the count rates obtained during reactor-ON and reactor-OFF periods with the energy threshold of 0.29 keV$ _{ee} $ shows no statistically significant difference. New upper limits on the number of CE$ \nu $NS events are evaluated on the basis of the residual ON$ - $OFF count rate spectrum.
Model-independent constraints on the Hubble constant using lensed quasars and the latest supernova
Liang Liu, Ai-Yang Bi, Li Tang, Ying Wu

2025, 49(5): 055107. doi: 10.1088/1674-1137/adbc87

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The Hubble constant $H_0$, a key parameter quantifying the present expansion rate of the universe, remains a subject of significant debate due to the persistent tension between early- and late-universe measurements. Strong gravitational lensing (SGL) time delays provide an independent avenue to constrain $H_0$. In this paper, we utilize seven SGL systems from the TDCOSMO sample to constrain $H_0$, employing the model-independent approaches: deep neural networks (DNN), Gaussian process (GP), polynomial fitting (polyfit) and Padé approximant (PA). Using these methods, we reconstruct unanchored luminosity distances from the Pantheon+ SNe Ia dataset and obtain $H_0=72.3^{+3.8}_{-3.6}$ km s⁻¹ Mpc⁻¹, $H_0=72.4^{+1.6}_{-1.7}$ km s⁻¹ Mpc⁻¹, $H_0=70.7^{+3.0}_{-3.1}$ km s⁻¹ Mpc⁻¹ and $H_0=74.0^{+2.7}_{-2.7}$ km s⁻¹ Mpc⁻¹, respectively. These estimates are consistent within 1σ level and align with local distance ladder results. Notably, the GP method achieves uncertainties that are half those of the DNN approach, whereas the DNN method offers more reliable confidence intervals in reconstruction at high redshifts. Our findings underscore the potential of these methodologies to refine constraints on $H_0$ and contribute to resolving the Hubble tension with future advancements.
Model for Glauber-type calculations of beam fragmentation at low energies
A. N. Ismailova, Yu. L. Parfenova, P. G. Sharov, D. M. Janseitov

2025, 49(5): 054106. doi: 10.1088/1674-1137/adb2fc

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In this study, a Glauber-type model for describing nuclear fragmentation in light targets at energies below 100 $A\cdot$MeV is presented. It is developed based on the Glauber model within the nucleon transparent limit, in which the Lorentz-invariant phase space factor is introduced to account for energy and momentum conservation. Accordingly, the scope of the applicability of the model is discussed. The longitudinal momentum distributions of the most neutron-rich nuclei (¹⁰Be, ⁹Li, and ⁸He), which were produced in a few nucleon removal reactions during the ¹¹B fragmentation of a Be target at beam energies of 10, 30, and 100 $A\cdot$MeV, are calculated. The results of the calculations are then compared to the predictions of statistical fragmentation models, such as the Goldhaber model. Using the new model, the asymmetric longitudinal momentum distributions at low energies are explained by the kinematical locus and geometry of the reaction.

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Pear Shape and Tetrahedral Shape Competition in Actinide Nuclei
Jie Yang, Irene Dedes, Xin Guan, Jerzy Dudek, Feng Pan, Jerry P. Draayer

Published: 2025-05-15

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Published: 2025-05-15

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Radially excited pion: electromagnetic form factor and the box contribution to the muon's g-2
Angel S. Miramontes, K. Raya, A. Bashir, P. Roig, G. Paredes-Torres

Published: 2025-05-12

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Published: 2025-05-12

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Unveiling Axion Signals in Galactic Supernovae with Future MeV Telescopes
Zhen Xie, Jiahao Liu, Bing Liu, Ruizhi Yang

Published: 2025-05-12

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Published: 2025-05-12

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Exploring chiral rotation in A ≈ 60 nuclei: Role of residual interactions
G. L. Ding, R. Dong, H. Y. Liu, J. Peng, Q. B. Chen

2025, 49(7): 074101-074101-8. doi: 10.1088/1674-1137/adc3fd

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To explore the possible existence of nuclear chirality in the $ A\approx 60 $ mass region, we study the doublet bands built on the configuration $ \pi f_{7/2}^{-1} \otimes \nu g_{9/2}^{1} $ using the particle rotor model (PRM) with residual proton-neutron interactions $ V_{pn} $ for cobalt isotopes. The energy spectra $ E(I) $, energy difference between the doublet bands $ \Delta E(I) $, electromagnetic transition probabilities $ B(M1) $ and $ B(E2) $, and the energy staggering $ S(I) $ of the doublet bands are calculated by varying the deformation parameters β and γ and moment of inertia $ \mathscr{J} $. The PRM calculations show that the parameters for the ideal chirality of the configuration $ \pi f_{7/2}^{-1} \otimes \nu g_{9/2}^{1} $ are $ \beta=0.25 $, $ \gamma=34^{\circ} $, and $\mathscr{J}= $$ 10\; \hbar^2/\rm MeV$. Subsequently, PRM calculations adopting these parameters show that $ \Delta E(I) $ and $ S(I) $ are sensitive to the residual proton-neutron interactions $ V_{pn} $. A weaker $ V_{pn} $ is more conducive to the existence of nuclear chirality. Finally, the evolution of the chirality with spin I is illustrated using the probability of the total angular momentum along the principal axes (K distribution) and the orientation with respect to the intrinsic frame $ \mathscr{P}(\theta,\varphi) $.

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Thermodynamics of Barrow Einstein-power-Yang-Mills AdS black hole in the restricted phase space
Yun-Zhi Du, Hui-Hua Zhao, Yang Zhang, Qiang Gu

2025, 49(7): 075102-075102-10. doi: 10.1088/1674-1137/adc7e1

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Due to quantum gravitational effects, Barrow proposed that the black hole horizon is "fractalized" into a sphereflake. Based on this idea, in this work we investigate the phase structure and stability of Einstein-Power-Yang-Mills (EPYM) AdS black holes in the restricted phase space, assuming the black hole event horizon has a fractal structure. From the first law of thermodynamics for EPYM AdS black holes in the restricted phase space, we find that the mass parameter should be interpreted as the internal energy. Moreover, the Smarr relation for this system in the restricted phase space is not a homogeneous function due to the fractal structure, which differs significantly from the corresponding relation in the extended phase space. The presence of a fractal structure can be regarded as a probe for phase transitions. Interestingly, for a fixed central charge in the EPYM AdS black hole system with a fractal structure, a supercritical phase transition also exists, similar to the case in the standard EPYM AdS black hole system. Furthermore, we investigate the effects of the fractal parameter ∆ and non-linear Yang-Mills parameter γ on the thermodynamical stability of this system are also investigated.

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Weak magnetic effect in quark-gluon plasma and local spin polarization
Jing-An Sun, Li Yan

2025, 49(7): 071001-071001-6. doi: 10.1088/1674-1137/adc120

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We propose the weak magnetic effect, which emerges as the dissipative correction to the quark phase space distribution function in quark-gluon plasma close to local thermal equilibrium, as a novel contribution to the observed Lambda hyperon local spin polarization. A finite field strength that is consistent with previous estimates of the magnetic field in heavy-ion collisions can be used to xplain the experimentally observed Lambda local spin polarization through all centrality classes. Moreover, the weak magnetic effect plays an unambiguous role in the ordering between the second-order and third-order modulations of experimental Lambda local spin polarization.

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Current Issued

2025 Vol. 49, No. 5
Published: 29 April 2025

Particles And Fields
Nuclear Physics
Particle And Nuclear Astrophysics And Cosmology