Chinese Physics C

Highlights

Solar neutrino background in high-pressure gaseous ⁸²SeF₆ TPC neutrinoless double beta decay experiments
Jiemiao Wang, Hulin Wang, Dongliang Zhang

2024, 48(4): 043003. doi: 10.1088/1674-1137/ad2675

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In this study, the possibility of observing a solar neutrino background in a future neutrinoless double beta decay experiment using a high-pressure gaseous ⁸²SeF₆ TPC is investigated. Various contributions are simulated, and possible features that could be used for event classification are discussed; two types of backgrounds are identified. The rate of multi-site background events is approximately 0.63 events/(ton·yr) in a 30 keV ROI window. This background could be effectively reduced to less than 0.0001 events/(ton·yr) (95% C.L.) while maintaining a high signal efficiency of 93% by applying a selection based on the number of clusters and energy of the leading cluster. The rate of the single-electron background events is approximately 0.01 events/(ton·yr) in the ROI. Assuming a reduction factor of 10 for the single-electron background events obtained via the algorithms developed for radioactive background rejection, the total background induced by the solar neutrino would be 0.001 events/(ton·yr), which is sufficiently small for conducting ton-level experiments.
Gravitational wave footprints from Higgs-portal scalegenesis with multiple dark chiral scalars
He-Xu Zhang, Shinya Matsuzaki, Hiroyuki Ishida

2024, 48(4): 045106. doi: 10.1088/1674-1137/ad2b4f

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We discuss the gravitational wave (GW) spectra predicted from the electroweak scalegenesis of the Higgs portal type with a large number of dark chiral flavors, which many flavor QCD would underlie and give the dynamical explanation of the negative Higgs portal coupling required to trigger the electroweak symmetry breaking. We employ the linear-sigma model as the low-energy description of dark many flavor QCD and show that the model undergoes ultra-supercooling due to the produced strong first-order thermal phase transition along the (approximately realized) flat direction based on the Gildener-Weinberg mechanism. Passing through evaluation of the bubble nucleation/percolation, we address the reheating and relaxation processes, which are generically non-thermal and nonadiabatic. Parametrizing the reheating epoch in terms of the e-folding number, we propose proper formulae for the redshift effects on the GW frequencies and signal spectra. It then turns out that the ultra-supercooling predicted from the Higgs-portal scalegenesis generically yields none of GW signals with the frequencies as low as nano Hz, unless the released latent heat is transported into another sector other than reheating the universe. Instead, models of this class prefer to give the higher frequency signals and still keeps the future prospected detection sensitivity, like at LISA, BBO, and DECIGO, etc. We also find that with large flavors in the dark sector, the GW signals are made further smaller and the peak frequencies higher. Characteristic phenomenological consequences related to the multiple chiral scalars include the prediction of dark pions with the mass much less than TeV scale, which is also briefly addressed.
Correlations of baryon and charge stopping in heavy ion collisions
Wendi Lv, Yang Li, Ziyang Li, Rongrong Ma, Zebo Tang, Prithwish Tribedy, Chun Yuen Tsang, Zhangbu Xu, Wangmei Zha

2024, 48(4): 044001. doi: 10.1088/1674-1137/ad243f

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Baryon numbers are theorized to be carried by valence quarks in the standard QCD picture of the baryon structure. Another theory proposed an alternative baryon number carrier, a non-perturbative Y-shaped configuration of the gluon field, called the baryon junction in the 1970s. However, neither of these theories has been verified experimentally. Recently, searching for the baryon junction by investigating the correlation of net-charge and net-baryon yields at midrapidity in heavy-ion collisions has been suggested. This paper presents studies of such correlations in collisions of various heavy ions from oxygen to uranium with the UrQMD Monte Carlo model. The UrQMD model implements valence quark transport as the primary means of charge and baryon stopping at midrapidity. Detailed studies are also conducted for isobaric $ _{40}^{96}{\rm{Zr}} $ + $ _{40}^{96}{\rm{Zr}} $ and $ _{44}^{96}{\rm{Ru}} $ + $ _{44}^{96}{\rm{Ru}} $ collisions. We found a universal trend of charge stopping with respect to baryon stopping and discovered that the charge stopping is always greater than the baryon stopping. This study provides a model baseline in valence quark transport for what is expected in net-charge and net-baryon yields at the midrapidity of relativistic heavy-ion collisions.

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The nuclear decay database in fission product mass region
Xiao-Long Huang, Dong Yang, Zhi-Gang Ge, Xiang-Han Wang, Yang-Yang Liu, Yong-Li Jin, Jian Li

Published: 2024-04-21

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Published: 2024-04-21

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Moving doubly heavy baryon in a strongly coupled plasma from holography
Xuan Liu, Jia-Jie Jiang, Xun Chen, Mitsutoshi Fujita, Akira Watanabe

Published: 2024-04-21

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Published: 2024-04-21

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The ${ \mathbf{\bar{q}q\bar{s}Q} \;\; \mathbf{(q=u,\,d;\,Q=c,\,b)} }$ tetraquark system in a chiral quark model
Gang Yang, Jialun Ping, Jorge Segovia

Published: 2024-04-21

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Published: 2024-04-21

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Analysis of the gluon distribution with next-to-leading order splitting function at small-x
Jingxuan Chen, Xiaopeng Wang, Yanbing Cai, Xurong Chen, Qian Wang

2024, 48(6): 063104-063104-7. doi: 10.1088/1674-1137/ad305d

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An approximated solution for the gluon distribution from DGLAP evolution equations with the NLO splitting function in the small-x limit is presented. We first obtain simplified forms of the LO and NLO splitting functions in the small-x limit. With these approximated splitting functions, we obtain the analytical gluon distribution using the Mellin transform. The free parameters in the boundary conditions are obtained by fitting the CJ15 gluon distribution data. We find that the asymptotic behavior of the gluon distribution is consistent with the CJ15 data; however, the NLO results considering the "ladder" structure of gluon emission are slightly better than the LO results. These results indicate that the corrections from NLO have a significant influence on the behavior of the gluon distribution in the small-x region. In addition, we investigate the DGLAP evolution of the proton structure function using the analytical solution of the gluon distribution. The differential structure function reveals that our results have a similar tendency to the CJ15 data at small-x.

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Impacts of gravitational-wave background from supermassive black hole binaries on the detection of compact binaries by LISA
Fan Huang, Yan-Chen Bi, Zhoujian Cao, Qing-Guo Huang

2024, 48(6): 065103-065103-6. doi: 10.1088/1674-1137/ad34c2

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In the frequency band of the Laser Interferometer Space Antenna (LISA), extensive research has been conducted on the impact of foreground confusion noise generated by galactic binaries within the Milky Way Galaxy. Additionally, recent evidence of a stochastic signal, announced by the NANOGrav, EPTA, PPTA, CPTA, and InPTA, indicates that the stochastic gravitational-wave background (SGWB) generated by supermassive black hole binaries (SMBHBs) can contribute strong background noise within the LISA band. Given the presence of such strong noise, it is expected to have significant impacts on LISA's scientific missions. In this study, we investigate the impacts of the SGWB generated by SMBHBs on the detection of individual massive black hole binaries, verified galactic binaries, and extreme mass ratio inspirals in the context of LISA. We find it essential to resolve and eliminate the excess noise from the SGWB to guarantee the success of LISA's missions.

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TALYS calculation and a short review of the experimental status of proton capture studies on p-nuclei: A guide to future investigation
Indrani Ray, Argha Deb

2024, 48(6): 064001-064001-10. doi: 10.1088/1674-1137/ad2dc3

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TALYS calculations were performed to obtain the theoretical proton capture cross-sections on the p-nuclei. A short review on the status of related experimental studies was also conducted. Some basic properties such as Q-values, Coulomb barrier, Gamow peak, Gamow Window, and decay properties of the parent and daughter nuclei were studied. Various experimental parameters, e.g., beam energy, beam current, targets, and detectors, used in experimental investigations reported in the literature, were tabulated. The results of the TALYS calculations in the Gamow region were compared with the corresponding experimental values wherever available. This study is expected to facilitate the planning of future experiments.

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Current Issued

2024 Vol. 48, No. 4
Published: 01 April 2024

Particles And Fields
Nuclear Physics
Particle And Nuclear Astrophysics And Cosmology