Correlations and Fluctuations in STAR

We report measurements for the balance function, transverse momentum fluctuations, and net charge fluctuations from Au+Au collisions at 20, 130, and 200 GeV as well as p+p and d+Au collisions at 200 GeV using STAR at RHIC. For Au+Au collisions at 200 GeV, we observe a narrowing of the balance function in central collisions. We observe dynamic transverse momentum fluctuations at all incident energies. Observables related to transverse momentum fluctuations and net charge fluctuations are similar for peripheral Au+Au collisions and inclusive p+p collisions while central Au+Au collisions deviate significantly from HIJING predictions.Comment: 4 pages, 3 figures, Contribution to Quark Matter 2004 Proceeding

Transverse energy distributions and J/ψJ/\psi production in Pb+Pb collisions

We have analyzed the latest NA50 data on transverse energy distributions and $J/\psi$ suppression in Pb+Pb collisions. The transverse energy distribution was analysed in the geometric model of AA collisions. In the geometric model, fluctuations in the number of NN collisions at fixed impact parameter are taken into account. Analysis suggests that in Pb+Pb collisions, individual NN collisions produces less $$, than in other AA collisions. The nucleons are more transparent in Pb+Pb collisions. The transverse energy dependence of the $J/\psi$ suppression was obtained following the model of Blaizot et al, where charmonium suppression is assumed to be 100% effective above a threshold density. With fluctuations in number of NN collisions taken into account, good fit to the data is obtained, with a single parameter, the threshold density.Comment: Revised version with better E_T fit. 4 pages, 2 figure

Modeling Hidden Nodes Collisions in Wireless Sensor Networks: Analysis Approach

This paper studied both types of collisions. In this paper, we show that advocated solutions for coping with hidden node collisions are unsuitable for sensor networks. We model both types of collisions and derive closed-form formula giving the probability of hidden and visible node collisions. To reduce these collisions, we propose two solutions. The first one based on tuning the carrier sense threshold saves a substantial amount of collisions by reducing the number of hidden nodes. The second one based on adjusting the contention window size is complementary to the first one. It reduces the probability of overlapping transmissions, which reduces both collisions due to hidden and visible nodes. We validate and evaluate the performance of these solutions through simulations

Multiplicity, average transverse momentum and azimuthal anisotropy in U+U collisions at sNN\sqrt{s_{NN}} = 200 GeV using AMPT model

Using a multi-phase transport (AMPT) model that includes the implementation of deformed Uranium nuclei, we have studied the centrality dependence of the charged particle multiplicity, , eccentricity (e2), triangularity (e3), their fluctuations, elliptic flow (v2) and triangular flow (v3) for different configurations of U+U collisions at midrapidity for \sqrt(s_NN)=200 GeV. The results are compared to the corresponding observations from Au+Au collisions. We find that for the U+U collisions the dNch/d\eta at midrapidity is enhanced by about 15-40% depending on the collision and model configuration chosen, compared to Au+Au collisions. The tip-to-tip collisions leads to the largest values of Nch,transverse energy (ET) and . The and its fluctuation shows a rich centrality dependence, whereas not much variations are observed for and its fluctuations. The U+U side-on-side collision configuration provides maximum values of and minimum values of eccentricity fluctuations, whereas for peripheral collisions and mid-central collisions minimum values of and maximum value of eccentricity fluctuations are observed for body-to-body configuration and the tip-to-tip configuration has minimum value of and maximum value of eccentricity fluctuations for central collisions. The calculated v2 closely correlates with the eccentricity in the model. It is smallest for the body-to-body configuration in peripheral and mid-central collisions while it is minimum for tip-to-tip configuration in central collisions. For peripheral collisions the v2 in U+U can be about 40% larger than in Au+Au whereas for central collisions it can be a factor 2 higher depending on the collision configuration. It is also observed that the v3(pT) is higher for tip-to-tip and body-to-body configurations compared to other systems for the collision centrality studied.Comment: 10 pages and 29 figures. Accepted for publication in Physical Review