Chinese Physics C

Highlights

Soft pattern of Rutherford scattering from heavy target mass expansion
Yu Jia, Jia-Yue Zhang

2025, 49(3): 033102. doi: 10.1088/1674-1137/acdb56

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We investigate the soft behavior of the tree-level Rutherford scattering process. We consider two types of Rutherford scattering processes: One in which a low-energy massless point-like projectile (say, a spin-${1/ 2}$ or spin-$ 0 $ electron) hits a static massive composite target particle carrying various spins (up to spin-$ 2 $), and one where a slowly-moving light projectile hits a heavy static composite target. For the first type, the unpolarized cross sections in the laboratory frame are found to exhibit universal forms in the first two orders of $ 1/M $ expansion yet differ at the next-to-next-to-leading order (though some terms at this order still remain universal or depend on the target spin in a definite manner). For the second type, at the lowest order in electron velocity expansion, through all orders in $ 1/M $, the unpolarized cross section is universal (also not sensitive to the projectile spin). The universality partially breaks down at relative order-$ v^2/M^2 $, though some terms at this order are still universal or depend on the target spin in a specific manner. We also employ the effective field theory approach to reproduce the soft behavior of the differential cross sections for when the target particle is a composite spin-${1/ 2}$ fermion.
Potential to identify neutrino mass ordering with reactor antineutrinos at JUNO
Angel Abusleme, Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Sebastiano Aiello, Muhammad Akram, Abid Aleem, Fengpeng An, Qi An, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Burin Asavapibhop, João Pedro Athayde Marcondes de André, Didier Auguste, Weidong Bai, Nikita Balashov, Wander Baldini, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Bellato, Marco Beretta, Antonio Bergnoli, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Iwan Morton-Blake, David Blum, Simon Blyth, Anastasia Bolshakova, Mathieu Bongrand, Clément Bordereau, Dominique Breton, Augusto Brigatti, Riccardo Brugnera, Riccardo Bruno, Antonio Budano, Jose Busto, Anatael Cabrera, Barbara Caccianiga, Hao Cai, Xiao Cai, Yanke Cai, Zhiyan Cai, Stéphane Callier, Antonio Cammi, Agustin Campeny, Chuanya Cao, Guofu Cao, Jun Cao, Rossella Caruso, Cédric Cerna, Vanessa Cerrone, Chi Chan, Jinfan Chang, Yun Chang, Auttakit Chatrabhuti, Chao Chen, Guoming Chen, Pingping Chen, Shaomin Chen, Yixue Chen, Yu C

2025, 49(3): 033104. doi: 10.1088/1674-1137/ad7f3e

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The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino experiment under construction in South China. This paper presents an updated estimate of JUNO’s sensitivity to neutrino mass ordering using the reactor antineutrinos emitted from eight nuclear reactor cores in the Taishan and Yangjiang nuclear power plants. This measurement is planned by studying the fine interference pattern caused by quasi-vacuum oscillations in the oscillated antineutrino spectrum at a baseline of 52.5 km and is completely independent of the CP violating phase and neutrino mixing angle θ₂₃. The sensitivity is obtained through a joint analysis of JUNO and Taishan Antineutrino Observatory (TAO) detectors utilizing the best available knowledge to date about the location and overburden of the JUNO experimental site, local and global nuclear reactors, JUNO and TAO detector responses, expected event rates and spectra of signals and backgrounds, and systematic uncertainties of analysis inputs. We find that a 3σ median sensitivity to reject the wrong mass ordering hypothesis can be reached with an exposure of about 6.5 years × 26.6 GW thermal power.
Layout optimization and performance analysis of large array of imaging atmospheric Cherenkov telescopes
Zhipeng Zhang, Ruizhi Yang, Shoushan Zhang, Zhen Xie, Jiali Liu, Liqiao Yin, Yudong Wang, Lingling Ma, Zhen Cao

2025, 49(3): 035001. doi: 10.1088/1674-1137/ad8e3f

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The large array of imaging atmospheric Cherenkov telescopes (LACT) is a planned array of 32 Cherenkov telescopes, each featuring 6-m diameter mirrors, to be constructed at the LHAASO site. This study focused on optimizing the array layout and analyzing the performance of LACT. Two observation modes were examined: large zenith angle observations for ultra-high energy events and small zenith angle observations for lower energy thresholds. For large zenith angles (60°), simulations indicate that an 8-telescope subarray can achieve an effective area of $ 3 \; \rm km^2 $ with excellent angular resolution. For small zenith angles, we optimized the layout of 4-telescope cells and the full 32-telescope array. The energy threshold of the full array is approximately 200 GeV, which is particularly crucial for studying transient phenomena such as gamma-ray bursts (GRBs) and active galactic nuclei (AGNs). This study provides essential guidance for finalizing the LACT layout design and estimating performance under various observational conditions. It also highlights the potential of LACT for conducting deep observations of ultra-high energy γ-ray sources, performing morphological studies of PeVatrons, and advancing time-domain γ-ray astronomy.

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New approach to alpha decay and cluster radioactivity using an extended form of the Sextic potential
V.P. Ndzono, A. Zarma, P. MahTsila, J.M. Ema'aEma'a, P. EleAbiama, G.H. Ben-Bolie

Published: 2025-02-25

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Published: 2025-02-25

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The unstable mode of the net-baryon density near the spinodal decomposition region
Shanjin Wu

Published: 2025-02-25

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Published: 2025-02-25

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Observational Signatures of Traversable Wormholes
Yiqian Chen, Lang Cheng, Peng Wang, Haitang Yang

Published: 2025-02-25

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Published: 2025-02-25

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Muon g − 2 with SU(2)_L multiplets
Takaaki Nomura, Hiroshi Okada

2025, 49(4): 043102-043102-12. doi: 10.1088/1674-1137/adabcf

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We propose a simple model to obtain a sizable muon anomalous magnetic dipole moment (muon $ g-2 $) that introduces several $ S U(2)_L $ multiplet fields without any additional symmetries. The neutrino mass matrix is simply induced via a type-II seesaw scenario in terms of $ S U(2)_L $ triplet Higgs with $ U(1)_Y $ hypercharge 1. In addition, we introduce an $ S U(2)_L $ quartet vector-like fermion with hypercharge $ 1/2 $ and scalar with hypercharge $ 3/2 $. The quartet fermion plays a crucial role in explaining muon $ g-2 $ causing the chiral flip inside a loop diagram with the mixing of triplet and quartet scalar bosons via the standard model Higgs. We conduct a numerical analysis and search for the allowed region in our parameter space and demonstrate the collider physics.

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An empirical formula of nuclear β-decay half-lives with the transition-strength contribution
Lei Tian, Wei-Feng Li, Ji-Yu Fang, Zhong-Ming Niu

2025, 49(4): 044110-044110-7. doi: 10.1088/1674-1137/ad9303

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An empirical formula of nuclear β-decay half-lives is proposed by including the transition-strength contribution. The inclusion of the transition-strength contribution can reduce nuclear β-decay half-lives by about an order of magnitude, and its effect gradually increases toward the neutron-rich or heavy nuclear regions. For nuclear β-decay half-lives less than 1 s, the empirical formula can describe the experimental data within approximately2 times, which is more accurate than the sophisticated microscopic models. The transition-strength contribution can also be effectively considered by refitting the parameters of other empirical formulas without the transition-strength term although they will still significantly deviate from the new empirical formula in light or heavy neutron-rich nuclear regions. This indicates that the inclusion of the transition-strength contribution in the empirical formula is crucial for the global description of nuclear β-decay half-lives. The extrapolation ability of the new empirical formula was verified by the newly measured β-decay half-lives.

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Friedmann’s universe controlled by Gauss-Bonnet modified gravity
F. dos Anjos, M. Novello

2025, 49(4): 045108-045108-14. doi: 10.1088/1674-1137/ad9b9e

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We consider a Lagrangian to describe gravity using a nonlinear term depending on the Gauss-Bonnet topological invariant. We examine the conditions for a bouncing and the existence of an ulterior accelerated phase of the universe. The original concept of Einstein's first paper on cosmology was to modify the equations that control the gravitational metric. Based on this, several authors have proposed different formalisms to modify general relativity. Herein, a function of the topological invariant is used in a homogeneous and isotropic cosmological model. First, a case with the topological invariant as a constant is thoroughly examined, yielding specific constraints on the evolution of the Hubble parameter. Subsequently, we study a function of the topological invariant squared. In an empty space-time scenario, the term that modifies Einstein’s equations functions as an effective geometrical density, and we map regions in the phase space in which the effective pressure is positive or negative. This results in non-trivial integral solutions such as cyclic stages of acceleration and deceleration of the scale factor in the model, among other behaviors. We add cosmic dust to the system, and for certain classes of solutions, we observe that the minimum positive value of the Hubble parameter is limited by the cosmic dust matter density. If this matter density reaches zero, the minimum value of the Hubble parameter also reaches zero.

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Current Issued

2025 Vol. 49, No. 3
Published: 28 February 2025

Particles And Fields
Nuclear Physics
Particle And Nuclear Astrophysics And Cosmology