NLO QCD corrections to processes with multiple electroweak bosons

The VBFNLO program package is a collection of Monte Carlo programs for the calculation of NLO QCD corrections to vector boson fusion cross sections, double and triple vector boson production, or the production of two electroweak bosons in association with an additional jet. An overview is given of the processes and features implemented in VBFNLO. WWgamma and Wgamma jet production are discussed as examples.Comment: 6 pages, 3 figures; talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology), October 25 - 30 2009, Ascona, Switzerlan

Pulsar Magnetospheric Emission Mapping: Images and Implications of Polar-Cap Weather

The beautiful sequences of ``drifting'' subpulses observed in some radio pulsars have been regarded as among the most salient and potentially instructive characteristics of their emission, not least because they have appeared to represent a system of subbeams in motion within the emission zone of the star. Numerous studies of these ``drift'' sequences have been published, and a model of their generation and motion articulated long ago by Ruderman & Sutherland (1975); but efforts thus far have failed to establish an illuminating connection between the drift phemomenon and the actual sites of radio emission. Through a detailed analysis of a nearly coherent sequence of ``drifting'' pulses from pulsar B0943+10, we have in fact identified a system of subbeams circulating around the magnetic axis of the star. A mapping technique, involving a ``cartographic'' transform and its inverse, permits us to study the character of the polar-cap emission ``map'' and then to confirm that it, in turn, represents the observed pulse sequence. On this basis, we have been able to trace the physical origin of the ``drifting-subpulse'' emission to a stably rotating and remarkably organized configuration of emission columns, in turn traceable possibly to the magnetic polar-cap ``gap'' region envisioned by some theories.Comment: latex with five eps figure

Pulsational instability of yellow hypergiants

Instability of population I (X=0.7, Y=0.02) massive stars against radial oscillations during the post-main sequence gravitational contraction of the helium core is investigated. Initial stellar masses are in the range from 65M_\odot to 90M_\odot. In hydrodynamic computations of self-exciting stellar oscillations we assumed that energy transfer in the envelope of the pulsating star is due to radiative heat conduction and convection. The convective heat transfer was treated in the framework of the theory of time-dependent turbulent convection. During evolutionary expansion of outer layers after hydrogen exhaustion in the stellar core the star is shown to be unstable against radial oscillations while its effective temperature is Teff > 6700K for Mzams=65M_\odot and Teff > 7200K for mzams=90M_\odot. Pulsational instability is due to the \kappa-mechanism in helium ionization zones and at lower effective temperature oscillations decay because of significantly increasing convection. The upper limit of the period of radial pulsations on this stage of evolution does not exceed 200 day. Radial oscillations of the hypergiant resume during evolutionary contraction of outer layers when the effective temperature is Teff > 7300K for Mzams=65M_\odot and Teff > 7600K for Mzams=90M_\odot. Initially radial oscillations are due to instability of the first overtone and transition to fundamental mode pulsations takes place at higher effective temperatures (Teff > 7700K for Mzams=65M_\odot and Teff > 8200K for Mzams=90M_\odot). The upper limit of the period of radial oscillations of evolving blueward yellow hypergiants does not exceed 130 day. Thus, yellow hypergiants are stable against radial stellar pulsations during the major part of their evolutionary stage.Comment: 20 pages, 7 gigures. Accepted for publication in Astronomy Letter

Next-to-leading order QCD corrections to Higgs boson production in association with a photon via weak-boson fusion at the LHC

Higgs boson production in association with a hard central photon and two forward tagging jets is expected to provide valuable information on Higgs boson couplings in a range where it is difficult to disentangle weak-boson fusion processes from large QCD backgrounds. We present next-to-leading order QCD corrections to Higgs production in association with a photon via weak-boson fusion at a hadron collider in the form of a flexible parton-level Monte Carlo program. The QCD corrections to integrated cross sections are found to be small for experimentally relevant selection cuts, while the shape of kinematic distributions can be distorted by up to 20% in some regions of phase space. Residual scale uncertainties at next-to-leading order are at the few-percent level.Comment: 17 pages, 7 figures, 1 tabl

Depth concentrations of deuterium ions implanted into some pure metals and alloys

Pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd-alloys (Pd-Ag, Pd-Pt, Pd-Ru, Pd-Rh) were implanted by 25 keV deuterium ions at fluences in the range (1.2{\div}2.3)x1022 D+/m2. The post-treatment depth distributions of deuterium ions were measured 10 days and three months after the implantation using Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS). Comparison of the obtained results allowed to make conclusions about relative stability of deuterium and hydrogen gases in pure metals and diluted Pd alloys. Very high diffusion rates of implanted deuterium ions from V and Pd pure metals and Pd alloys were observed. Small-angle X-ray scattering revealed formation of nanosized defects in implanted corundum and titanium.Comment: 12 pages, 9 figure

Correlations and charge distributions of medium heavy nuclei

The effects of long- and short-range correlations on the charge distributions of some medium and heavy nuclei are investigated. The long-range correlations are treated within the Random Phase Approximation framework and the short-range correlations with a model inspired to the Correlation Basis Function theory. The two type of correlations produce effects of the same order of magnitude. A comparison with the empirical charge distribution difference between 206Pb and 205Tl shows the need of including both correlations to obtain a good description of the data.Comment: 20 pages, Latex, accepted for publication in Jour. Phys.

The balance of Polo-like kinase 1 in tumorigenesis

Polo-like kinase 1 (Plk1) belongs to a family of conserved serine/threonine kinases with a polo-box domain, which have similar but non-overlapping functions in the cell cycle progression. Plk1 plays a key role to ensure the normal mitosis. Interestingly, overexpression of Plk1 is associated with tumor development and could serve as a prognostic marker for many cancers. Due to Plk1 overexpression, several Plk1 inhibitors have been developed and tested for the cancer treatment. However, in a recent study, it has been suggested that down-regulation of Plk1 could also induce aneuploidy and tumor formation in vivo. Therefore, a normal level of Plk1 is important for mitosis. And caution should be taken when Plk1 inhibitors are used in the clinical trial and their side effects including tumorigenesis should be carefully evaluated

Galactic chemical evolution : Carbon through zinc

Copyright © 2006. The American Astronomical Society. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1086/508914We calculate the evolution of heavy-element abundances from C to Zn in the solar neighborhood, adopting our new nucleosynthesis yields. Our yields are calculated for wide ranges of metallicity (Z = 0-Z circle dot) and the explosion energy (normal supernovae and hypernovae), based on the light-curve and spectra fitting of individual supernovae. The elemental abundance ratios are in good agreement with observations. Among the alpha-elements, O, Mg, Si, S, and Ca show a plateau at [Fe/H] <= -1, while Ti is underabundant overall. The observed abundance of Zn ([Zn/Fe] similar to 0) can be explained only by the high-energy explosion models, as it requires a large contribution of hypernovae. The observed decrease in the odd-Z elements (Na, Al, and Cu) toward low [Fe/H] is reproduced by the metallicity effect on nucleosynthesis. The iron-peak elements (Cr, Mn, Co, and Ni) are consistent with the observed mean values at -2.5 less than or similar to [Fe/H] less than or similar to -1, and the observed trend at the lower metallicity can be explained by the energy effect. We also show the abundance ratios and the metallicity distribution functions of the Galactic bulge, halo, and thick disk. Our results suggest that the formation timescale of the thick disk is similar to 1-3 Gyr.Peer reviewe

The Crab Nebula: interpretation of CHANDRA observations

We interpret the observed X-ray morphology of the central part of the Crab Nebula (torus + jets) in terms of the standard theory by Kennel and Coroniti (1984). The only new element is the inclusion of anisotropy in the energy flux from the pulsar in the theory. In the standard theory of relativistic winds, the Lorentz factor of the particles in front of the shock that terminates the pulsar relativistic wind depends on the polar angle as $\gamma=\gamma_0+\gamma_m\sin^2\theta$, where $\gamma_0 \sim 200$ and $\gamma_m \sim 4.5\times 10^6$. The plasma flow in the wind is isotropic. After the passage of the pulsar wind through the shock, the flow becomes subsonic with a roughly constant (over the plerion volume) pressure $P={1\over 3}n\epsilon$, where $n$ is the plasma particle density and $\epsilon$ is the mean particle energy. Since $\epsilon \sim \gamma mc^2$, a low-density region filled with the most energetic electrons is formed near the equator. A bright torus of synchrotron radiation develops here. Jet-like regions are formed along the pulsar rotation axis, where the particle density is almost four orders of magnitude higher than that in the equatorial plane, because the particle energy there is four orders of magnitude lower. The energy of these particles is too low to produce detectable synchrotron radiation. However, these quasi-jets become comparable in brightness to the torus if additional particle acceleration takes place in the plerion. We also present the results of our study of the hydrodynamic interaction between an anisotropic wind and the interstellar medium. We compare the calculated and observed distributions of the volume intensity of X-ray radiation.Comment: 38 pages, 5 figures. To be published in Astronomy Letters, 2002, N 6, p.

Confronting the Superbubble Model with X-ray Observations of 30 Dor C

We present an analysis of XMM-Newton observations of the superbubble 30 Dor C and compare the results with the predictions from the standard wind-blown bubble model. We find that the observed X-ray spectra cannot be fitted satisfactorily with the model alone and that there is evidence for nonthermal X-ray emission, which is particularly important at > 4 keV. The total unabsorbed 0.1-10 keV luminosities of the eastern and western parts of the bubble are ~3 10^36 erg/s and ~5 10^36 erg/s, respectively. The unabsorbed 0.1-10 keV luminosity of the bubble model is 4 10^36 erg/s and so the power-law component contributes between 1/3 and 1/2 to the total unabsorbed luminosity in this energy band. The nature of the hard nonthermal emission is not clear, although recent supernovae in the bubble may be responsible. We expect that about one or two core-collapse supernovae could have occured and are required to explain the enrichment of the hot gas, as evidenced by the overabundance of alpha-elements by a factor of 3, compared to the mean value of 0.5 solar for the interstellar medium in the Large Magellanic Cloud. As in previous studies of various superbubbles, the amount of energy currently present in 30 Dor C is significantly less than the expected energy input from the enclosed massive stars over their lifetime. We speculate that a substantial fraction of the input energy may be radiated in far-infrared by dust grains, which are mixed with the hot gas because of the thermal conduction and/or dynamic mixing.Comment: 25 pages, 4 figures. To appear in The Astrophysical Journal, August 20, 2004 issu