Higlights
  • Scalar quintuplet minimal dark matter with Yukawa interactions: perturbative up to the Planck scale
    We confront the perturbativity problem in the real scalar quintuplet minimal dark matter model. In the original model, the quintuplet quartic self-coupling inevitably hits a Landau pole at a scale ~1014 GeV, far below the Planck scale. In order to push up this Landau pole scale, we extend the model with a fermionic quintuplet and three fermionic singlets which couple to the scalar quintuplet via Yukawa interactions. Involving such Yukawa interactions at a scale ~1010 GeV can not only keep all couplings perturbative up to the Planck scale, but can also explain the smallness of neutrino masses via the type-I seesaw mechanism. Furthermore, we identify the parameter regions favored by the condition that perturbativity and vacuum stability are both maintained up to the Planck scale.
  • Description of the critical point symmetry in 124Te by IBM-2
    Based on the neutron and proton degrees of freedom, low-lying energy levels, $ E2 $ , $ M1 $ , and $ E0 $ transition strengths of nucleus 124Te have been calculated by the neutron-proton interacting boson model. The calculated results are reasonably consistent with the experimental data. By comparing the key observables of the states at the critical point of $ {\rm U}_{\pi \nu}(5) $ - $ {\rm O}_{\pi \nu}(6) $ transition with the experimental data and calculated results, we show that the 124Te is a possible nucleus at the critical point of the second-order phase transition from vibration to unstable rotation, and such a critical point exhibits slight triaxial rotation. The 0 $_2^ + $ state of 124Te can be interpreted as the lowest state of the first-excited family of the intrinsic levels in the critical point symmetry.
  • Criticality of QCD in a holographic QCD model with critical end point
    The thermodynamics of strongly interacting matter near the critical end point are investigated in a holographic QCD model, which can describe the QCD phase diagram in $ T-\mu $ plane qualitatively. Critical exponents along different axes ( $ \alpha,\beta,\gamma,\delta $ ) are extracted numerically. It is given that $ \alpha\approx 0$ , $\beta\approx 0.54 $ , $\gamma \approx 1.04$ , and $\delta \approx 2.97$ , which is similar to the three-dimensional Ising mean-field approximation and previous holographic QCD model calculations. We also discuss the possibilities to go beyond the mean field approximation by including the full back-reaction of the chiral dynamics in the holographic framework.
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  • Evaluating the topological charge density with the symmetric multi-probing method
    Published: 2019-02-15, doi: 10.1088/1674-1137/43/3/033102
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    We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing (SMP) method in 3 modes. Since the topological charge Q for a given lattice configuration must be an integer number, it is easy to estimate the systematic error (the deviation of Q to the nearest integer). The results demonstrate a high efficiency and accuracy in calculating the trace of the inverse of a large sparse matrix with locality by using the SMP sources when compared to using point sources. We also show the correlation between the errors and probing scheme parameter $r_{\min}$ , as well as lattice volume $N_{L}$ and lattice spacing a. It is found that the computational time for calculating the trace by employing the SMP sources is less dependent on $N_{L}$ than by using point sources. Therefore, the SMP method is very suitable for calculations on large lattices.
  • Revisiting hidden-charm pentaquarks from QCD sum rules
    Published: 2019-02-15, doi: 10.1088/1674-1137/43/3/034104
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    We revisit hidden-charm pentaquark states $ P_c(4380) $ and $ P_c(4450) $ using the method of QCD sum rules by requiring the pole contribution to be greater than or equal to 30% in order to better that the one-pole parametrization is valid. We find two mixing currents, and our results suggest that $ P_c(4380) $ and $ P_c(4450) $ can be identified as hidden-charm pentaquark states having $ J^P=3/2^- $ and $ 5/2^+ $ , respectively. However, there still exist other possible spin-parity assignments, such as $ J^P=3/2^+ $ and $ J^P=5/2^- $ , which must be clarified in further theoretical and experimental studies.
  • Chiral phase structure of the sixteen meson states in the SU(3) Polyakov linear-sigma model for finite temperature and chemical potential in a strong magnetic field
    Published: 2019-02-15, doi: 10.1088/1674-1137/43/3/034103
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    In characterizing the chiral phase-structure of pseudoscalar ( $J^{pc}=0^{-+}$ ), scalar ( $J^{pc}=0^{++}$ ), vector ( $J^{pc}=1^{--}$ ) and axial-vector ( $J^{pc}=1^{++}$ t) meson states and their dependence on temperature, chemical potential, and magnetic field, we utilize the SU(3) Polyakov linear-sigma model (PLSM) in the mean-field approximation. We first determine the chiral (non)strange quark condensates, $\sigma_l$ and $\sigma_s$ , and the corresponding deconfinement order parameters, $\phi$ and $\phi^*$ , in thermal and dense (finite chemical potential) medium and finite magnetic field. The temperature and the chemical potential characteristics of nonet meson states normalized to the lowest bosonic Matsubara frequency are analyzed. We note that all normalized meson masses become temperature independent at different critical temperatures. We observe that the chiral and deconfinement phase transitions are shifted to lower quasicritical temperatures with increasing chemical potential and magnetic field. Thus, we conclude that the magnetic field seems to have almost the same effect as the chemical potential, especially on accelerating the phase transition, i.e. inverse magnetic catalysis. We also find that increasing the chemical potential enhances the mass degeneracy of the various meson masses, while increasing the magnetic field seems to reduce the critical chemical potential, at which the chiral phase transition takes place. Our mass spectrum calculations agree well with the recent PDG compilations and PNJL, lattice QCD calculations, and QMD/UrQMD simulations.
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