PACIAE model capability in describing net proton moments

PACIAE 2.0, a parton and hadron cascade model, is employed to investigate the dependence of the moments of net proton event distributions on reaction energies varying from RHIC to LHC energy in p + p collisions. It is found that net proton moments and moment products are sensitive to the collision energy except the moment product k?? ² which is almost independent of the collision energy. The PACIAE results are in line with experimental data.     

In-Medium Kaon Potential and Nuclear Equation of State Measured in Nucleus–Nucleus Collisions

The kaon production in heavy ion collisions at intermediate energies provides a sensitive probe to study the in-medium properties and nuclear equation of state of hadrons. Properties of kaons in dense hadronic matter are important for a better understanding of both, the possible restoration of chiral symmetry in dense hadronic matter and the properties of nuclear matter at high densities. We investigated the in-medium kaon potential and nuclear equation of state by transverse mass spectra of K ⁺ mesons in heavy ion collisions. We use quantum molecular dynamics (QMD) models based on covariant kaon dynamics to simulate ${_{28}^{58}Ni +_{28}^{58}Ni}$ collisions at 1.93 A GeV, to analyze the transverse mass spectra of K ⁺. Calculated results with a repulsive in-medium K ⁺N potential can reasonably describe the features of KaoS data. They also shown that the transverse mass spectrum of K ⁺ mesons is a sensitive observable to probe the kaon in-medium potential in dense nuclear matter.     

A Protein from Aloe vera that Inhibits the Cleavage of Human Fibrin(ogen) by Plasmin

A protease inhibitor protein with the molecular mass of 11,804.931 Da (analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) was isolated from Aloe vera leaf gel and designated as AVPI-12. The isoelectric point of the protein is about 7.43. The first ten amino acid sequence from the N-terminal was found to be R–D–W–A–E–P–N–D–G–Y, which did not match other protease inhibitors in database searches and other publications, indicating AVPI-12 is a novel protease inhibitor. The band protein of AVPI-12 migrated further on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) than reducing SDS-PAGE. This result indicated that the molecule of AVPI-12 did not contain interchain disulfide bonds, but appeared to have intrachain disulfide bonds instead. AVPI-12 strongly resisted digestion by the serine proteases human plasmin and bovine trypsin. The protein could protect the γ-subunit of human fibrinogen from plasmin and trypsin digestion, similar to the natural plasma serine protease inhibitor α₂-macroglobulin. The protein also could protect the γ-subunit of fibrinogen from the cysteine protease papain. AVPI-12 also exhibited dose-dependent inhibition of the fibrinogenolytic activity of plasmin, similar to α₂-macroglobulin. The fibrinolytic inhibitory activity of AVPI-12 and the small-angle X-ray scattering showed that the protein could protect human fibrin clot from complete degradation by plasmin. The inhibition of the fibrinogenolytic and fibrinolytic activities of plasmin by AVPI-12 suggests that the inhibitor has potential for use in antifibrinolytic treatment.     

Azimuthal Distributions of K + Mesons in Heavy-Ion Collisions

Strange mesons are considered to be sensitive to in-medium modifications. Theory predicts a repulsive K ⁺ N potential and an attractive K ^? N potential in dense matter. A repulsive K ⁺ N potential would repel the K ⁺ mesons from the bulk of the nucleons and therefore cause a preferred out-of-plane emission of K ⁺ mesons at midrapidity and a directed flow opposite to the nucleons at target and projectile rapidity. One of observables to probe in-medium effects is the azimuthal emission pattern of K ⁺ mesons in heavy ion collisions. KaoS collaboration has measured the azimuthal distributions of K ⁺ mesons in Au + Au reactions at 1.5 A GeV and Ni + Ni reactions at 1.93 A GeV. Data show that K ⁺ mesons exhibit a pronounced enhancement at ${\phi = {90}^\circ}$ , i.e. perpendicular to the reaction plane. The data have also been fitted using the first two components of a Fourier series to get the directed flow v ₁ and elliptic flow v ₂. We used the quantum molecular dynamics model based on the covariant kaon dynamics to simulate the Au + Au collisions at 1.5 A GeV and the Ni + Ni collisions at 1.93 A GeV, to analyze the azimuthal distributions of K ⁺ mesons, and to calculate v ₁ and v ₂ of K ⁺ mesons. Calculated results with a repulsive in-medium K ⁺ N potential can reasonably describe the features of KaoS data. This indicates that the azimuthal distribution is one of sensitive probes to extract information on in-medium properties at high densities.     

Net-Proton Nonstatistical Moments in High-Energy pp Collisions in PACIAE Model

The parton and hadron cascade model, PACIAE 2.0, is employed to calculate the net-proton nonstatistical moments in pp collisions at RHIC and LHC energies. By analyzing the results in the full phase space, it is found that the nonstatistical moments and moments products are significantly dependent on the collision energy. It is suggested that the net-proton nonstatistical moments in pp collisions may be studied in partial phase spaces with the PACIAE model.     

Comparative study of the forward and backward methods for calculating jet properties in pp collisions at s~(1/2)=7 TeV

We propose a forward method based on PYTHIA6.4 to study the jet properties in ultra-relativistic pp collisions.In the forward method,the partonic initial states are first generated with PYTHIA6.4 and then hadronized in the Lund string fragmentation model,and finally the hadronic jets are constructed from the created hadrons.Jet properties calculated with the forward method for pp collisions at √s=7 TeV are comparable to those calculated with the usual anti-kt algorithm(backward method)in PYTHIA6.4.The comparison between the backward and forward methods may contribute to the understanding of the partonic origin of jets in the backward method.     

Analysis of excited quark propagator effects on neutron charge form factor

The European Physical Journal A - The first neutron star (NS) merger observed by advanced LIGO and Virgo, GW170817, and its fireworks of electromagnetic counterparts across the entire...