Quarkonium dissociation in quark-gluon plasma via ionization in magnetic field

We study the impact of magnetic fields generated in relativistic heavy ion collisions on the decay probability of quarkonium produced in the central rapidity region. The quark and anti-quark components are subject to mutually orthogonal electric and magnetic fields in the quarkonium comoving frame. In the presence of an electric field, quarkonium has finite dissociation probability. We use the WKB approximation to derive the dissociation probability. We found that quarkonium dissociation energy, i.e. the binding energy at which dissociation probability is of order unity, increases with the magnetic field strength. It also increases with quarkonium momentum in the laboratory frame due to Lorentz boost of electric field in the comoving frame. As a consequence, J/Psi in plasma dissociates at lower temperature then it would be in the absence of a magnetic field. We argue that J/Psi's produced in heavy-ion collisions at LHC with P_T>9GeV would dissociate even in vacuum. In plasma, J/Psi dissociation in magnetic field is much stronger due to decrease of its binding energy with temperature. We discuss the phenomenological implications of our results.Comment: 16 pages, 4 figures; v2: discussion and references added, typos fixed; v3: discussion section expande

Visualizing Experimental Designs for Balanced ANOVA Models using Lisp-Stat

The structure, or Hasse, diagram described by Taylor and Hilton (1981, American Statistician) provides a visual display of the relationships between factors for balanced complete experimental designs. Using the Hasse diagram, rules exist for determining the appropriate linear model, ANOVA table, expected means squares, and F-tests in the case of balanced designs. This procedure has been implemented in Lisp-Stat using a software representation of the experimental design. The user can interact with the Hasse diagram to add, change, or delete factors and see the effect on the proposed analysis. The system has potential uses in teaching and consulting

Structural Studies on a Mitochondrial Glyoxalase II

Glyoxalase 2 is a β-lactamase fold-containing enzyme that appears to be involved with cellular chemical detoxification. Although the cytoplasmic isozyme has been characterized from several organisms, essentially nothing is known about the mitochondrial proteins. As a first step in understanding the structure and function of mitochondrial glyoxalase 2 enzymes, a mitochondrial isozyme (GLX2-5) from Arabidopsis thaliana was cloned, overexpressed, purified, and characterized using metal analyses, EPR and 1H NMR spectroscopies, and x-ray crystallography. The recombinant enzyme was shown to bind 1.04 ± 0.15 eq of iron and 1.31 ± 0.05 eq of Zn(II) and to exhibit kcat and Km values of 129 ± 10 s-1 and 391 ± 48 μm, respectively, when using S-d-lactoylglutathione as the substrate. EPR spectra revealed that recombinant GLX2-5 contains multiple metal centers, including a predominant Fe(III)Z-n(II) center and an anti-ferromagnetically coupled Fe(III)Fe(II) center. Unlike cytosolic glyoxalase 2 from A. thaliana, GLX2-5 does not appear to specifically bind manganese. 1H NMR spectra revealed the presence of at least eight paramagnetically shifted resonances that arise from protons in close proximity to a Fe(III)Fe(II) center. Five of these resonances arose from solvent-exchangeable protons, and four of these have been assigned to NH protons on metal-bound histidines. A 1.74-Å resolution crystal structure of the enzyme revealed that although GLX2-5 shares a number of structural features with human GLX2, several important differences exist. These data demonstrate that mitochondrial glyoxalase 2 can accommodate a number of different metal centers and that the predominant metal center is Fe(III)Zn(II)

On viscous flow and azimuthal anisotropy of quark-gluon plasma in strong magnetic field

We calculate the viscous pressure tensor of the quark-gluon plasma in strong magnetic field. It is azimuthally anisotropic and is characterized by five shear viscosity coefficients, four of which vanish when the field strength eB is much larger than the plasma temperature squared. We argue, that the azimuthally anisotropic viscous pressure tensor generates the transverse flow with asymmetry as large as 1/3, even not taking into account the collision geometry. We conclude, that the magnitude of the shear viscosity extracted from the experimental data ignoring the magnetic field must be underestimated.Comment: 10 page