X(3872) and Its Heavy Quark Spin Symmetry Partners in QCD Sum Rules

X(3872) presents many surprises after its discovery more than ten years ago. Understanding its properties is crucial to understand the spectrum of possible exotic mesons. In this work, X(3872) meson and its heavy quark spin symmetry (HQSS) partners (including the mesons in the bottom sector) are studied within the QCD Sum Rules approach using a current motivated by the molecular picture of X(3872). We predict four heavy partners to X(3872) and bottomonium with the masses and J^PC quantum numbers. Obtained results are in good agreement with the previous studies and available experimental data within errors.Comment: 18 pages, 12 figures, 3 tables, Accepted by European Physical Journal

QCD sum rules for the anti-charmed pentaquark

We present a QCD sum rule analysis for the anti-charmed pentaquark state with and without strangeness. While the sum rules for most of the currents are either non-convergent or dominated by the $DN$ continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the $DN$ continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict a more stable pentaquark states when the antiquark is heavy.Comment: 19 pages, 8 figures, REVTex, revised version,new figures added and references update

Effects of astrocyte on weak signal detection performance of Hodgkin–Huxley neuron

By virtue of recent developments in brain measurement technology, it is now recognized that information processing in brain includes not only neurons but also astrocytes. For this reason, to illustrate the effects of astrocyte on information processing in neuronal systems, we research the weak signal detection performance of the Hodgkin–Huxley neuron under the effect of astrocyte. It is found that the weak signal detection performance of the neuron exhibits the stochastic resonance phenomenon depending on noise intensity, where the presence of astrocyte with an optimal coupling strength significantly increases the detection performance of the neuron when compared the one without astrocyte. The obtained results also reveal that there is an optimal weak signal frequency ensuring the best detection performance. Besides, we show that the colored noise exhibits a better performance than white Gaussian noise on improving the weak signal detection capacity of the neuron; moreover, the weak signal detection performance of the neuron demonstrates a resonance-like dependence on the correlation time of the noise. Finally, we investigate the effects of calcium channel noise. Although the calcium channel noise generally reduces the weak signal detection performance of the neuron, the optimal coupling strength warranting the best detection performance critically depends on its intensity. © 2019, Springer Nature B.V

Effects of Calcium Channel Noise on Weak Signal Detection in Neuron-Astrocyte Interactions

In this study, the effects of electrically non-excitable astrocyte cell on the weak signal detection capacity of Hodgkin-Huxley neuron are investigated. To do this, by applying a subthreshold weak signal to neuron, we investigate the weak signal detection capacity of the neuron depending on calcium channel noise stemmed from random open-close fluctuations of calcium channels. Obtained results show that astrocyte decreases the weak signal detection capacity of Hodgkin-Huxley neuron