216,976 research outputs found
First Result of Net-Charge Jet-Correlations from STAR
We presented results on azimuthal correlation of net-charge with high
trigger particles. It is found that the net-charge correlation shape is similar
to that of total-charge. On the near-side, the net-charge and total-charge
spectra have similar shape and both are harder than the inclusives. On
the away-side, the correlated spectra are not much harder than the inclusives,
and the net-charge/total-charge ratio increases with and is similar to
the inclusive ratio
Ion-induced nucleation. II. Polarizable multipolar molecules
Density functional theory is applied to ion-induced nucleation of polarizable multipolar molecules. The asymmetric nature of the ion-molecule interaction is shown to cause the sign preference in ion-induced nucleation. When the ion-molecule interaction is weak, the observed sign preference is consistent with that of the bare ion-molecule interaction potential and decreases with increasing supersaturation. However, as the ion-molecule interaction becomes stronger, the sign preference in the reversible work exhibits some nontrivial behavior. For molecular parameters applicable for CS2 and CH4, the predicted values of the reversible work of nucleation depend on the sign of the ion charge, yielding a difference in the nucleation rate by factors of 10 to 10^(2) and 10 to 10^(5), respectively
Ion-induced nucleation: A density functional approach
Density functional theory is applied to ion-induced nucleation of dipolar molecules. The predicted reversible work shows a sign preference, resulting in a difference in the nucleation rate by a factor of 10–10^2, for realistic values of model parameters. The sign effect is found to decrease systematically as the supersaturation is increased. The asymmetry of a molecule is shown to be directly responsible for the sign preference in ion-induced nucleation
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Age-related changes in blood-brain barrier integrity in C57BL/6J mice
The blood-brain barrier (BBB) is formed by the endothelial cells of the brain microvasculature, which control the molecular traffic between the blood and brain to maintain the neural microenvironment
Concurrence in collective models
We review the entanglement properties in collective models and their
relationship with quantum phase transitions. Focusing on the concurrence which
characterizes the two-spin entanglement, we show that for first-order
transition, this quantity is singular but continuous at the transition point,
contrary to the common belief. We also propose a conjecture for the concurrence
of arbitrary symmetric states which connects it with a recently proposed
criterion for bipartite entanglement.Comment: 8 pages, 2 figures, published versio
Binary nucleation of sulfuric acid-water: Monte Carlo simulation
We have developed a classical mechanical model for the H2SO4/H2O binary system. Monte Carlo simulation was performed in a mixed ensemble, in which the number of sulfuric acid molecules is fixed while that of water molecules is allowed to fluctuate. Simulation in this ensemble is computationally efficient compared to conventional canonical simulation, both in sampling very different configurations of clusters relevant in nucleation and in evaluating the free energy of cluster formation. The simulation yields molecular level information, such as the shape of the clusters and the dissociation behavior of the acid molecule in the cluster. Our results indicate that the clusters are highly nonspherical as a result of the anisotropic intermolecular interactions and that a cluster with a given number of acid molecules has several very different conformations, which are close in free energy and hence equally relevant in nucleation. The dissociation behavior of H2SO4 in a cluster differs markedly from that in bulk solution and depends sensitively on the assumed value of the free energy f(hb) of the dissociation reaction H2SO4+H2O-HSO4-. H3O+. In a small cluster, no dissociation is observed. As the cluster size becomes larger, the probability of having an HSO4-. H3O+ ion pair increases. However, in clusters relevant in nucleation, the resulting ion pairs remain in contact; about 240 water molecules are required to observe behavior that resembles that in bulk solution. If a larger value of f(hb) is assumed to reflect its uncertainty, the probability of dissociation becomes negligible. A reversible work surface obtained for a condition typical of vapor to liquid nucleation suggests that the rate-limiting step of new particle formation is a binary collision of two hydrated sulfuric acid molecules. The ion pairs formed by dissociation play a key role in stabilizing the resulting cluster. The reversible work surface is sensitive to the assumed value of f(hb), thus pointing to the need for an accurate estimate of the quantity either by ab initio calculations or experiments
The LHC di-photon Higgs signal predicted by little Higgs models
Little Higgs theory naturally predicts a light Higgs boson whose most
important discovery channel at the LHC is the di-photon signal . In this work we perform a comparative study for this signal in
some typical little Higgs models, namely the littlest Higgs model (LH), two
littlest Higgs models with T-parity (named LHT-I and LHT-II) and the simplest
little Higgs modes (SLH). We find that compared with the Standard Model
prediction, the di-photon signal rate is always suppressed and the suppression
extent can be quite different for different models. The suppression is mild
(\lsim 10%) in the LH model but can be quite severe () in other
three models. This means that discovering the light Higgs boson predicted by
the little Higgs theory through the di-photon channel at the LHC will be more
difficult than discovering the SM Higgs boson.Comment: 17 pages, 4 figures, 1 tabl
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