Possible ΔΔ\Delta\Delta dibaryons in the quark cluster model

In the framework of RGM, the binding energy of one channel $\Delta\Delta_{(3,0)}$($d^*$) and $\Delta\Delta_{(0,3)}$ are studied in the chiral SU(3) quark cluster model. It is shown that the binding energies of the systems are a few tens of MeV. The behavior of the chiral field is also investigated by comparing the results with those in the SU(2) and the extended SU(2) chiral quark models. It is found that the symmetry property of the $\Delta\Delta$ system makes the contribution of the relative kinetic energy operator between two clusters attractive. This is very beneficial for forming the bound dibaryon. Meanwhile the chiral-quark field coupling also plays a very important role on binding. The S-wave phase shifts and the corresponding scattering lengths of the systems are also given.Comment: LeTex with 2 ps figure

Magnetic rotations in 198Pb and 199Pb within covariant density functional theory

Well-known examples of shears bands in the nuclei 198Pb and 199Pb are investigated within tilted axis cranking relativistic mean-field theory. Energy spectra, the relation between spin and rotational frequency, deformation parameters and reduced $M1$ and $E2$ transition probabilities are calculated. The results are in good agreement with available data and with calculations based on the phenomenological pairing plus-quadrupole-quadrupole tilted-axis cranking model. It is shown that covariant density functional theory provides a successful microscopic and fully self-consistent description of magnetic rotation in the Pb region showing the characteristic properties as the shears mechanism and relatively large B(M1) transitions decreasing with increasing spin.Comment: 22 pages, 8 figure

Far apart yet close: social media on acculturation among international students in the UK

This paper investigates international students’ acculturation, an important aspect for universities to consider when they try to develop a positive loyal customer relationship with international students. The paper presents the influences of social media usage on international students’ acculturation process in both psychological and behavioural aspects, and whether international students’ acculturation predicts students’ academic achievement, perceived value and university loyalty. Self-identification is examined for its moderating effect between social media usage and Chinese international students’ acculturation. This study collected samples from Chinese international students studying in UK universities. The results find that Chinese international students’ psychological acculturation to the host culture has no significant relationship with their academic achievement, but their strong self-identification can help with their host culture acculturation. This study makes contributions in current acculturation research and managerial practice for universities which target international markets

Multipole polarizability of a graded spherical particle

We have studied the multipole polarizability of a graded spherical particle in a nonuniform electric field, in which the conductivity can vary radially inside the particle. The main objective of this work is to access the effects of multipole interactions at small interparticle separations, which can be important in non-dilute suspensions of functionally graded materials. The nonuniform electric field arises either from that applied on the particle or from the local field of all other particles. We developed a differential effective multipole moment approximation (DEMMA) to compute the multipole moment of a graded spherical particle in a nonuniform external field. Moreover, we compare the DEMMA results with the exact results of the power-law graded profile and the agreement is excellent. The extension to anisotropic DEMMA will be studied in an Appendix.Comment: LaTeX format, 2 eps figures, submitted for publication

Top Quark Rare Decays via Loop-Induced FCNC Interactions in Extended Mirror Fermion Model

Flavor changing neutral current (FCNC) interactions for a top quark $t$ decays into $Xq$ with $X$ represents a neutral gauge or Higgs boson, and $q$ a up- or charm-quark are highly suppressed in the Standard Model (SM) due to the Glashow-Iliopoulos-Miami mechanism. Whilst current limits on the branching ratios of these processes have been established at the order of $10^{-4}$ from the Large Hadron Collider experiments, SM predictions are at least nine orders of magnitude below. In this work, we study some of these FCNC processes in the context of an extended mirror fermion model, originally proposed to implement the electroweak scale seesaw mechanism for non-sterile right-handed neutrinos. We show that one can probe the process $t \to Zc$ for a wide range of parameter space with branching ratios varying from $10^{-6}$ to $10^{-8}$, comparable with various new physics models including the general two Higgs doublet model with or without flavor violations at tree level, minimal supersymmetric standard model with or without $R$-parity, and extra dimension model.Comment: 30 pages, 8 figures, 2 tables and 1 appendix. Version to appear in NP

Stability of Discrete Solitons in the Presence of Parametric Driving

In this brief report, we consider parametrically driven bright solitons in the vicinity of the anti-continuum limit. We illustrate the mechanism through which these solitons become unstable due to the collision of the phase mode with the continuous spectrum, or eigenvelues bifurcating thereof. We show how this mechanism typically leads to complete destruction of the bright solitary wave.Comment: 4 pages, 4 figure