Temperature-dependent Cross Sections for Charmonium Dissociation in Collisions with Pions and Rhos in Hadronic Matter

Meson-charmonium dissociation reactions governed by the quark interchange are studied with temperature-dependent quark potentials. Quark-antiquark relative-motion wave functions and masses of charmonia and charmed mesons are determined by the central spin-independent part of the potentials or by the central spin-independent part and a smeared spin-spin interaction. The prominent temperature dependence of the masses is found. Based on the potentials, the wave functions, and the meson masses, we obtain temperature-dependent cross sections for fifteen pion-charmonium and rho-charmonium dissociation reactions. The numerical cross sections are parametrized for future applications in hadronic matter. The particular temperature dependence of the J/psi bound state leads to unusual behavior of the cross sections for endothermic J/psi dissociation reactions. The quantum numbers of psi' and chi_c can not make their difference in mass in the temperature region 0.6T_c < T < T_c, but can make the psi' dissociation different from the chi_c dissociation.Comment: 52 pages, 23 figures, 6 table

Electrical Neutrality and Symmetry Restoring Phase Transitions at High Density in a Two-Flavor Nambu-Jona-Lasinio Model

A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe two-flavor normal quark matter. Depending on that $m_0/\Lambda$, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be second or first order. A complete phase diagram of $u$ quark chemical potential versus $m_0$ is given. With the electrical neutrality constraint, the region where second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value of $m_0/\Lambda$ from QCD phenomenology, the phase transition must be first order.Comment: 9 pages, 1 figur

Constructing Confidence Intervals of the Summary Statistics in the Least-Squares SROC Model

The accuracy of a diagnostic test is often evaluated with the measures of sensitivity and specificity, and the joint dependence between these two measures is captured by receiver operating characteristic (ROC) curve. To combine multiple testing results from studies that are assumed to follow the same underlying probability law, a smooth summary receiver operating characteristic (SROC) curve can be fitted. Moses, Shapiro, and Littenberg (1993) proposed a least-squares approach to fit the smooth SROC curve, and the variances of the estimated parameters were derived by ignoring the variance of the independent variable. Since the independent variable was in fact random, the variances were likely underestimated. Hence we propose another way to estimate the variances of the statistics of interest, and use a real example to demonstrate the differences. We also perform a simulation study to examine these two approaches. The results suggest that the least squares estimates of the coefficients are biased, and that the averaged confidence coverage is not equal to its nominal level, regardless of the methods. While Moses et al.\u27s method tends to underestimate the confidence interval, our method sometimes overestimates the interval, depending on the ratio of the intra-study variation over the inter-study variation. Our estimation of the variances appears to be slightly better than the method proposed by Moses et al. because the coverage probability of the confidence interval is closer to the nominal level

Influence of Reciprocal links in Social Networks

In this Letter, we empirically study the influence of reciprocal links, in order to understand its role in affecting the structure and function of directed social networks. Experimental results on two representative datesets, Sina Weibo and Douban, demonstrate that the reciprocal links indeed play a more important role than non-reciprocal ones in both spreading information and maintaining the network robustness. In particular, the information spreading process can be significantly enhanced by considering the reciprocal effect. In addition, reciprocal links are largely responsible for the connectivity and efficiency of directed networks. This work may shed some light on the in-depth understanding and application of the reciprocal effect in directed online social networks

Design of super-efficient mixer based on induced charge electroosmotic

The super-efficient sample mixing induced by the induced-charge electrokinetic flow around conducting/Janus cylinder was numerically studied in a confined |U-shaped microchannel with suddenly applied DC weak electric filed. It’s found that there are four large circulations around the conducting cylinder and two smaller circulations around the Janus cylinder. The results show that samples can still be well mixed with high flux due to the induced electroosmosis. It is demonstrated that the local flow circulations provide effective means to enhance the flow mixing between different solutions. The dependence of the degree of mixing enhancement on the electric field is also predicted