Underlying Event Studies for LHC Energies

Underlying event was originally defined by the CDF collaboration decades ago. Here we improve the original definition to extend our analysis for events with multiple-jets. We introduce a definition for surrounding rings/belts and based on this definition the jet- and surrounding-belt-excluded areas will provide a good underlying event definition. We inverstigate our definition via the multiplicity in the defined geometry. In parallel, mean transverse momenta of these areas also studied in proton-proton collisions at $\sqrt{s}=7$ TeV LHC energy.Comment: 6 pages and 4 figure

Friedmann branes with variable tension

We introduce brane-worlds with non-constant tension, strenghtening the analogy with fluid membranes, which exhibit a temperature-dependence according to the empirical law established by E\"otv\"os. This new degree of freedom allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We establish the covariant dynamics on a brane with variable tension in full generality, by considering asymmetrically embedded branes and allowing for non-standard model fields in the 5-dimensional space-time. Then we apply the formalism for a perfect fluid on a Friedmann brane, which is embedded in a 5-dimensional charged Vaidya-Anti de Sitter space-time.Comment: 12 pages, to appear in Phys. Rev.

Gravitational radiation reaction in compact binary systems: Contribution of the quadrupole-monopole interaction

The radiation reaction in compact spinning binaries on eccentric orbits due to the quadrupole-monopole interaction is studied. This contribution is of second post-Newtonian order. As result of the precession of spins the magnitude $L$ of the orbital angular momentum is not conserved. Therefore a proper characterization of the perturbed radial motion is provided by the energy $E$ and angular average $\bar{L}$. As powerful computing tools, the generalized true and eccentric anomaly parametrizations are introduced. Then the secular losses in energy and magnitude of orbital angular momentum together with the secular evolution of the relative orientations of the orbital angular momentum and spins are found for eccentric orbits by use of the residue theorem. The circular orbit limit of the energy loss agrees with Poisson's earlier result.Comment: accepted for publication in Phys. Rev.

Non-uniform Braneworld Stars: an Exact Solution

The first exact interior solution to Einstein's field equations for a static and non-uniform braneworld star with local and non-local bulk terms is presented. It is shown that the bulk Weyl scalar ${\cal U}(r)$ is always negative inside the stellar distribution, in consequence it reduces both the effective density and the effective pressure. It is found that the anisotropy generated by bulk gravity effect has an acceptable physical behaviour inside the distribution. Using a Reissner-N\"{o}rdstrom-like exterior solution, the effects of bulk gravity on pressure and density are found through matching conditions.Comment: 22 pages, 3 figures, version to be published in International Journal of Modern Physics D (IJMPD

Differences in high p_t meson production between CERN SPS and RHIC heavy ion collisions

In this talk we present a perturbative QCD improved parton model calculation for light meson production in high energy heavy ion collisions. In order to describe the experimental data properly, one needs to augment the standard pQCD model by the transverse momentum distribution of partons ("intrinsic k_T"). Proton-nucleus data indicate the presence of nuclear shadowing and multiscattering effects. Further corrections are needed in nucleus-nucleus collisions to explain the observed reduction of the cross section. We introduce the idea of proton dissociation and compare our calculations with the SPS and RHIC experimental data.Comment: Talk presented by G. Papp at Zakopane 2001 School, Zakopane, 2001 June; 10 pages with 3 EPS figure

Asymmetric Swiss-cheese brane-worlds

We study a brane-world cosmological scenario with local inhomogeneities represented by black holes. The brane is asymmetrically embedded into the bulk. The black strings/cigars penetrating the Friedmann brane generate a Swiss-cheese type structure. This universe forever expands and decelerates, as its general relativistic analogue. The evolution of the cosmological fluid however can proceed along four branches, two allowed to have positive energy density, one of them having the symmetric embedding limit. On this branch a future pressure singularity can arise for either (a) a difference in the cosmological constants of the cosmological and black hole brane regions (b) a difference in the left and right bulk cosmological constants. While the behaviour (a) can be avoided by a redefinition of the fluid variables, (b) establishes a critical value of the asymmetry over which the pressure singularity occurs. We introduce the pressure singularity censorship which bounds the degree of asymmetry in the bulk cosmological constant. We also show as a model independent generic feature that the asymmetry source term due to the bulk cosmological constant increases in the early universe. In order to obey the nucleosynthesis constraints, the brane tension should be constrained therefore both from below and from above. With the maximal degree of asymmetry obeying the pressure singularity censorship, the higher limit is 10 times the lower limit. The degree of asymmetry allowed by present cosmological observations is however much less, pushing the upper limit to infinity.Comment: v2: considerably expanded, 19 pages, 8 figures, many new references. Pressure singularity censorship introduced, strict limits on the possible degree of asymmetry derived. v3: model independent analysis shows that the asymmetry bounds the brane tension from above. Limits on the maximal tension set. Version published in JCA

Crystallization and preliminary crystallographic analysis of dUTPase from the helper phage Φ11 of Staphylococcus aureus

Staphylococcus aureus superantigen-carrying pathogenicity islands (SaPIs) have a determinant role in spreading virulence genes among bacterial populations that constitute a major health hazard. Repressor (Stl) proteins are responsible for transcriptional regulation of pathogenicity island genes. Recently, a derepressing interaction between the repressor Stl SaPIbov1 with dUTPase from the Φ11 helper phage was suggested [Tormo-Mas et al. (2010). Nature 465, 779-782]. Towards elucidating the molecular mechanism of this interaction, this study reports expression, purification, and X-ray analysis of Φ11 dUTPase that contains a phage-specific polypeptide segment not present in other dUTPases. Crystals were obtained using the hanging-drop vapor-diffusion method at room temperature. Data were collected from one type of crystal to 2.98 Å resolution. The crystal of Φ11 dUTPase belonged to the cubic space group I23, with unit-cell parameters a=98.16 Å, α=β=γ= 90.00o