The study of the negative pion production in neutron-proton collisions at beam momenta below 1.8 GeV/c

A detailed investigation of the reaction np -> pp\pi^{-} has been carried out using the data obtained with the continuous neutron beam produced by charge exchange scattering of protons off a deuterium target. A partial wave event-by-event based maximum likelihood analysis was applied to determine contributions of different partial waves to the pion production process. The combined analysis of the np -> pp\pi^{-} and pp -> pp\pi^{0} data measured in the same energy region allows us to determine the contribution of isoscalar partial waves (I=0) in the momentum range from 1.1 up to 1.8 GeV/c. The decay of isoscalar partial waves into (^1S_0)_{pp}\pi$ channel provides a good tool for a determination of the pp S-wave scalar scattering length in the final state which was found to be a_{pp}=-7.5\pm 0.3 fm.Comment: 6 pages, 6 figure

The Chiral MagnetoHydroDynamics of QCD fluid at RHIC and LHC

The experimental results on heavy ion collisions at RHIC and LHC indicate that QCD plasma behaves as a nearly perfect fluid described by relativistic hydrodynamics. Hydrodynamics is an effective low-energy Theory Of Everything stating that the response of a system to external perturbations is dictated by conservation laws that are a consequence of the symmetries of the underlying theory. In the case of QCD fluid produced in heavy ion collisions, this theory possesses anomalies, so some of the apparent classical symmetries are broken by quantum effects. Even though the anomalies appear as a result of UV regularization and so look like a short distance phenomenon, it has been realized recently that they also affect the large distance, macroscopic behavior in hydrodynamics. One of the manifestations of anomalies in relativistic hydrodynamics is the Chiral Magnetic Effect (CME). At this conference, a number of evidences for CME have been presented, including i) the disappearance of charge asymmetry fluctuations in the low-energy RHIC data where the energy density is thought to be below the critical one for deconfinement; ii) the observation of charge asymmetry fluctuations in Pb-Pb collisions at the LHC. Here I give a three-page summary of some of the recent theoretical and experimental developments and of the future tests that may allow to establish (or to refute) the CME as the origin of the observed charge asymmetry fluctuations.Comment: 4 pages, talk at Quark Matter 2011 Conference, Annecy, France, 23-28 May 201

Event-by-event correlations between Λ\Lambda (Λˉ\bar{\Lambda}) hyperon global polarization and handedness with charged hadron azimuthal separation in Au+Au collisions at sNN=27 GeV\sqrt{s_{\text{NN}}} = 27 \text{ GeV} from STAR

Global polarizations ($P$) of $\Lambda$ ($\bar{\Lambda}$) hyperons have been observed in non-central heavy-ion collisions. The strong magnetic field primarily created by the spectator protons in such collisions would split the $\Lambda$ and $\bar{\Lambda}$ global polarizations ($\Delta P = P_{\Lambda} - P_{\bar{\Lambda}} < 0$). Additionally, quantum chromodynamics (QCD) predicts topological charge fluctuations in vacuum, resulting in a chirality imbalance or parity violation in a local domain. This would give rise to an imbalance ($\Delta n = \frac{N_{\text{L}} - N_{\text{R}}}{\langle N_{\text{L}} + N_{\text{R}} \rangle} \neq 0$) between left- and right-handed $\Lambda$ ($\bar{\Lambda}$) as well as a charge separation along the magnetic field, referred to as the chiral magnetic effect (CME). This charge separation can be characterized by the parity-even azimuthal correlator ($\Delta\gamma$) and parity-odd azimuthal harmonic observable ($\Delta a_{1}$). Measurements of $\Delta P$, $\Delta\gamma$, and $\Delta a_{1}$ have not led to definitive conclusions concerning the CME or the magnetic field, and $\Delta n$ has not been measured previously. Correlations among these observables may reveal new insights. This paper reports measurements of correlation between $\Delta n$ and $\Delta a_{1}$, which is sensitive to chirality fluctuations, and correlation between $\Delta P$ and $\Delta\gamma$ sensitive to magnetic field in Au+Au collisions at 27 GeV. For both measurements, no correlations have been observed beyond statistical fluctuations.Comment: 10 pages, 10 figures; paper from the STAR Collaboratio

Hyperon polarization along the beam direction relative to the second and third harmonic event planes in isobar collisions at sNN\sqrt{s_{NN}} = 200 GeV

The polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild $p_T$ dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagree with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and $p_T$ dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.Comment: 6 pages, 5 figures, Published in Physical Review Letter

S-adenosylmethionine: DNA-cytosine 5-methyltransferase from a Novikoff rat hepatoma cell line.

Partial purification of DNA methylase from Novikoff rat hepatoma cells is described. Contamination with other proteins persists although the enzyme preparation has a high specific activity and is purified 980-fold over homogenate activity. Evidence suggests, but does not prove, that there may be more than one species of DNA methylase in these cells. The enzyme has two broad pH optima at pH 7.0 and 7.5 and most readily methylates heterologous denatured DNAs although complex reaction kinetics indicate that native DNAs may eventually be methylated to an equal or greater level. The preparation of undermethylated DNA from Novikoff cells is also described. Undermethylated homologous DNA is an 85-fold greater acceptor of methyl groups than fully methylated Novikoff cell DNA. In contrast to other DNA substrates, the enzyme preparation methylates native undermethylated homologous DNA at a 3.5-fold greater than denatured undermethylated homologous DNA

Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD final State interactions (THESEUS) for FAIR-NICA-SPSBES/RHIC energies

We present a new event generator based on the three-fluid hydrodynamics (3FH) approach, followed by a particlization at the hydrodynamic decoupling surface and a subsequent UrQMD afterburner stage based on the microscopic UrQMD transport model that accounts for hadronic final state interactions. First results for Au+Au collisions are presented. The following topics are addressed: the directed flow, transversemass spectra, as well as rapidity distributions of protons, pions and kaons for two model equations of state, one with a first-order phase transition, the other with a crossover transition. Preliminary results on the femtoscopy are also discussed.We analyze the accuracy of reproduction of the 3FH results by the new event generator and the effect of the subsequent UrQMD afterburner stage

Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD final State interactions (THESEUS) for FAIR-NICA-SPSBES/RHIC energies

We present a new event generator based on the three-fluid hydrodynamics (3FH) approach, followed by a particlization at the hydrodynamic decoupling surface and a subsequent UrQMD afterburner stage based on the microscopic UrQMD transport model that accounts for hadronic final state interactions. First results for Au+Au collisions are presented. The following topics are addressed: the directed flow, transversemass spectra, as well as rapidity distributions of protons, pions and kaons for two model equations of state, one with a first-order phase transition, the other with a crossover transition. Preliminary results on the femtoscopy are also discussed.We analyze the accuracy of reproduction of the 3FH results by the new event generator and the effect of the subsequent UrQMD afterburner stage