Highlights
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Solar neutrino background in high-pressure gaseous 82SeF6 TPC neutrinoless double beta decay experiments
2024, 48(4): 043003. doi: 10.1088/1674-1137/ad2675In 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.
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Gravitational wave footprints from Higgs-portal scalegenesis with multiple dark chiral scalars
2024, 48(4): 045106. doi: 10.1088/1674-1137/ad2b4fWe 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.
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Correlations of baryon and charge stopping in heavy ion collisions
2024, 48(4): 044001. doi: 10.1088/1674-1137/ad243fBaryon 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.
Just Accepted
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Role of magnetic fields on the outer crust in a magnetar
Published: 2024-04-17
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Determination of the resonant parameters of
$ \chi_{c0}(3915) $ with global fitPublished: 2024-04-11 -
The quasi-Gaussian distribution of DMIGM in fast radio bursts may bias the constraints on the Hubble constant
Published: 2024-04-11
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B − L model with D4 × Z4 × Z2 symmetry for fermion mass hierarchies and mixings
2024, 48(6): 063102-063102-20. doi: 10.1088/1674-1137/ad2f23Show AbstractWe constructed a gauge
$ B-L $ model with$ D_4\times Z_4\times Z_2 $ symmetry to explain the quark and lepton mass hierarchies and their mixings with realistic CP phases via the type-I seesaw mechanism. Six quark mases, three quark mixing angles, and the CP phase in the quark sector take the central values whereas Yukawa couplings in the quark sector are diluted in a range of difference of three orders of magnitude by the perturbation theory at the first order. Concerning the neutrino sector, a small neutrino mass is achieved by the type-I seesaw mechanism. Both inverted and normal neutrino mass hierarchies are consistent with the experimental data. The predicted sum of neutrino masses for normal and inverted hierarchies, the effective neutrino masses, and the Dirac CP phase are also consistent with recently reported limits. -
Critical behavior and Joule-Thomson expansion of charged AdS black holes surrounded by exotic fluid with modified Chaplygin equation of state
2024, 48(6): 065101-065101-12. doi: 10.1088/1674-1137/ad32c0Show AbstractBy considering the concept of a unified single fluid model, referred to as modified Chaplygin gas (MCG), which amalgamates dark energy and dark matter, we explore the thermodynamic characteristics of charged anti-de Sitter (AdS) black holes existing in an unconventional fluid accompanied by MCG. To accomplish this objective, we derive the equations of state by regarding the charge
$ Q^{2} $ as a thermodynamic variable. The effects of MCG parameters on the critical thermodynamic quantities ($ \psi_{c} $ ,$ T_{c} $ ,$ Q_{c}^{2} $ ) are examined, followed by a detailed analysis of the$ Q^{2}-\psi $ diagram. To provide a clearer explanation of the phase transition, we present an analysis of the Gibbs free energy. It is important to note that if the Hawking temperature exceeds the critical temperature, a distinct pattern is observed known as swallowtail behavior. This indicates that the system undergoes a first-order phase transition from a smaller black hole to a larger one. The critical exponent of the system is found to be in complete agreement with that of the van der Waals fluid system. Furthermore, we investigate the impact of MCG parameters and black hole charge on Joule-Thomson (J-T) expansion in the extended phase space. The J-T coefficient is examined to pinpoint the exact region experiencing cooling or heating, and the observation reveals that the presence of negative heat capacity results in the occurrence of a cooling process. The impact of MCG on the inversion curve of charged black holes exhibits a striking resemblance to that observed in most multi-dimensional black hole systems. In addition, it is worth noting that certain parameters exert a significant influence on the ratio$\dfrac{T_{\min}}{T_{c}}$ . For specific values of the MCG parameters, the ratio is consistent with the charged AdS black hole. The parameters γ and β have a non-negligible effect on the isenthalpic curve. -
Mass suppression effect in QCD radiation and hadron angular distribution in jet
2024, 48(6): 063101-063101-6. doi: 10.1088/1674-1137/ad2f22Show AbstractThe finite mass of the heavy quark suppresses the collimated radiations; this is generally referred to as the dead cone effect. In this paper, we study the distribution of hadron multiplicity over the hadron opening angle with respect to the jet axis for various jet flavors. The corresponding measurement can be the most straightforward and simplest approach to explore the dynamical evolution of the radiations in the corresponding jet, which can expose the mass effect. We also propose a transverse energy-weighted angular distribution, which sheds light on the interplay between perturbative and non-perturbative effects in the radiation. Through Monte-Carlo simulations, our calculations show that the dead cone effect can be clearly observed by finding the ratio between the b and light-quark (inclusive) jets; this is expected to be measured at the LHC in the future.
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ISSN 1674-1137 CN 11-5641/O4
Original research articles, Ietters and reviews Covering theory and experiments in the fieids of
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Cover Story
- Cover Story (Issue 4, 2024) | Advancing gravitational wave astronomy: AI-enhanced detection and real-time analysis in the presence of glitches
- Cover Story (Issue 3, 2024) | First measurement of the ground-state mass of 22Al helpsto evaluate the ab-initio theory
- Cover Story (Issue 2, 2024) | Quark/gluon taggers light the way to new physics
- Cover story (Issue 6, 2023) |Joint constraints on cosmological parameters using future multi-band gravitational wave standard siren observations
- Cover Story (Issue 5, 2023) | Production and decay of polarized hyperon-antihyperon pairs