Highlights

Positivity in electronpositron scattering: testing the axiomatic quantum field theory principles and probing the existence of UV states
2021, 45(2): 023108. doi: 10.1088/16741137/abcd8cWe consider the positivity bounds on dimension8 fourelectron operators and study two related phenomenological aspects at future lepton colliders. First, if positivity is violated, probing such violations will revolutionize our understanding of the fundamental pillars of quantum field theory and the Smatrix theory. We observe that positivity violation at scales of 110 TeV can potentially be probed at future lepton colliders even if one assumes that dimension6 operators are also present. Second, the positive nature of the dimension8 parameter space often allows us to either directly infer the existence of UVscale particles together with their quantum numbers or exclude them up to certain scales in a modelindependent way. In particular, dimension8 positivity plays an important role in the test of the Standard Model. If no deviations from the Standard Model are observed, it allows for simultaneous exclusion limits on all kinds of potential UVcomplete models. Unlike the dimension6 case, these limits apply regardless of the UV model setup and cannot be removed by possible cancellations among various UV contributions. This thus consists of a novel and universal test to confirm the Standard Model. We demonstrate with realistic examples how all the previously mentioned possibilities, including the test of positivity violation, can be achieved. Hence, we provide an important motivation for studying dimension8 operators more comprehensively.

Diffuseness effect and radial basis function network for optimizing α decay calculations
2021, 45(2): 024105. doi: 10.1088/16741137/abcc5cA radial basis function network (RBFN) approach is adopted for the first time to optimize the calculation of
$ \alpha $ decay halflife in the generalized liquid drop model (GLDM), while concurrently incorporating the surface diffuseness effect. The calculations presented herein agree closely with the experimental halflives for 68 superheavy nuclei (SHN), achieving a remarkable reduction of 40% in the rootmeansquare (rms) deviations of halflives. Furthermore, using the RBFN method, the halflives for four SHN isotopes, ^{252288}Rf, ^{272310}Fl, ^{286316}119, and ^{292318}120, are predicted using the improved GLDM with the diffuseness correction and the decay energies from WS4 and FRDM as inputs. Therefore, we conclude that the diffuseness effect should be embodied in the proximity energy. Moreover, increased application of neural network methods in nuclear reaction studies is encouraged. 
Charmed and ϕ meson decay constants from 2+1flavor lattice QCD
2021, 45(2): 023109. doi: 10.1088/16741137/abcd8fOn a lattice with 2+1flavor dynamical domainwall fermions at the physical pion mass, we calculate the decay constants of
$ D_{s}^{(*)} $ ,$ D^{(*)} $ , and$ \phi $ . The lattice size is$ 48^3\times96 $ , which corresponds to a spatial extension of$ \sim5.5 $ fm, with a lattice spacing of$ a\approx 0.114 $ fm. For the valence light, strange, and charm quarks, we use overlap fermions at several mass points close to their physical values. Our results at the physical point are$ f_D = 213(5) $ MeV,$ f_{D_s} = 249(7) $ MeV,$ f_{D^*} = 234(6) $ MeV,$ f_{D_s^*} = 274(7) $ MeV, and$ f_\phi = 241(9) $ MeV. The couplings of$ D^* $ and$ D_s^* $ to the tensor current ($ f_V^T $ ) can be derived from ratios$ f_{D^*}^T/f_{D^*} = 0.91(4) $ and$ f_{D_s^*}^T/f_{D_s^*} = 0.92(4) $ , respectively, which are the first lattice quantum chromodynamics (QCD) results. We also obtain ratios$ f_{D^*}/f_D = 1.10(3) $ and$ f_{D_s^*}/f_{D_s} = 1.10(4) $ , which reflect the size of heavy quark symmetry breaking in charmed mesons. Ratios$ f_{D_s}/f_{D} = 1.16(3) $ and$ f_{D_s^*}/f_{D^*} = 1.17(3) $ can be taken as a measure of SU(3) flavor symmetry breaking.
Just Accepted
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Renormalizability of leading order covariant chiral nucleonnucleon interaction
Published: 20210225

Relative probabilities of breakup channels in reactions of ^{6,7}Li with ^{209}Bi at energies around and above the Coulomb barrier
Published: 20210225

The collisional Penrose process of 4D rotational EinsteinGaussBonnet black holes
Published: 20210225
In Press
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Multiscalar BL extension based on S_{4} flavor symmetry for neutrino masses and mixing
Published: 20210226, doi: 10.1088/16741137/abe1c7Show AbstractA multiscalar and nonrenormalizable
$BL$ extension of the standard model (SM) with$S_4$ symmetry which successfully explains the recently observed neutrino oscillation data is proposed. The tiny neutrino masses and their hierarchies are generated via the typeI seesaw mechanism. The model reproduces the recent experiments of neutrino mixing angles and Dirac CP violating phase in which the atmospheric angle$(\theta_{23})$ and the reactor angle$(\theta_{13})$ get the bestfit values while the solar angle$(\theta_{12})$ and Dirac CP violating phase ($\delta $ ) are in$3\, \sigma $ range of the bestfit value for the normal hierarchy (NH). For the inverted hierarchy (IH),$\theta_{13}$ gets the bestfit value and$\theta_{23}$ together with$\delta $ are in the$1\, \sigma $ range, while$\theta_{12}$ is in$3\, \sigma $ range of the bestfit value. The effective neutrino masses are predicted to be$\langle m_{ee}\rangle=6.81 \,\, {\rm{meV}}$ for the NH and$\langle m_{ee}\rangle=48.48\,\, {\rm{meV}}$ for the IH, in good agreement with the most recent experimental data. 
Systematic study of twoproton radioactivity within a Gamowlike model
Published: 20210226, doi: 10.1088/16741137/abe10fShow AbstractIn this study, based on the Gamowlike model, we systematically analyze twoproton (
$2p$ ) radioactivity halflives of nuclei near or beyond the proton drip line. It is found that the calculated results can reproduce experimental data well. Furthermore, using this model, we predict the halflives of possible$2p$ radioactivity candidates whose$2p$ radioactivity is energetically allowed or observed but not yet quantified in the latest table of evaluated nuclear properties, i.e., NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Sreeja formula, and Liu formula. 
Origin of hardening in spectra of cosmic ray nuclei at a few hundred GeV using AMS02 data
Published: 20210226, doi: 10.1088/16741137/abe03dShow AbstractMany experiments have confirmed spectral hardening at a few hundred GeV in the spectra of cosmic ray (CR) nuclei. Three different origins have been proposed: primary source acceleration, propagation, and the superposition of different kinds of sources. In this work, a broken power law has been employed to fit each of the spectra of cosmic ray nuclei from AMS02 directly, for rigidities greater than 45 GeV. The fitting results of the break rigidity and the spectral index differences less than and greater than the break rigidity show complicated relationships among different nuclear species, which cannot be reproduced naturally by a simple primary source scenario or a propagation scenario. However, with a natural and simple assumption, the superposition of different kinds of sources could have the potential to explain the fitting results successfully. Spectra of CR nuclei from a single future experiment, such as DAMPE, will provide us the opportunity to do cross checks and reveal the properties of the different kinds of sources.
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ISSN 16741137 CN 115641/O4
Original research articles, Ietters and reviews Covering theory and experiments in the fieids of
 Particle physics
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 Particle and nuclear astrophysics
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