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We present a QCD-based model where rescattering between final state partons in deep inelastic scattering leads to events with large rapidity gaps and a leading proton. In the framework of this model the amplitude for multiple gluon exchanges is calculated in the eikonal approximation to all orders in perturbation theory. Both large and small invariant mass MX limits are considered. The model succe
We discuss exclusive double diffractive (EDD) production of heavy quark - heavy antiquark pairs at high energies. Differential distributions for cc̄ at √s = 1.96 GeV and for bb̄ at √s = 14 TeV are shown and discussed. Irreducible leading-order bb̄ background to Higgs production is calculated in several kinematical variables. The signal-to-background ratio is shown and several improvements are sugg
We calculate differential cross sections for exclusive double diffractive (EDD) production of open charm in proton-proton and proton-antiproton collisions. Sizeable cross sections are found. The EDD contribution constitutes about 1% of the total inclusive cross section for open charm production. A few differential distributions are shown and discussed. The EDD contribution falls faster both with t
We construct a QCD-based model where soft gluon rescattering between final state partons in deep inelastic scattering leads to events with large rapidity gaps and a leading proton. The model successfully describes the precise HERA data on the diffractive deep inelastic structure function in the whole available kinematical range.
We discuss central exclusive production (CEP) of the tensor χc(2 +) meson in proton-(anti)proton collisions at Tevatron, RHIC, and LHC energies. The amplitude for the process is derived within the kt-factorization approach. Differential and total cross sections are calculated for several unintegrated gluon distribution functions (UGDFs). We compare exclusive production of all charmonium states χc(
The generalized Gerasimov-Drell-Hearn sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the Q2 dependence of the Gerasimov-Drell-Hearn sum rule. We take into account higher order radiative and higher-twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent pro
In this article we describe simulations of the hadronic decay of Higgs bosons produced in association with vector bosons at linear and hadronic colliders. We use the Monte Carlo at next-to-leading-order (MC@NLO) matching prescription with the Herwig++ event generator to predict various spectra of the resulting b (b) over bar pairs and compare our results with leading order and matrix element corre
only using electric-dipole forbidden emission lines, in what we label forbidden-line spectroscopy, we identified several energy levels in cadmium-like tungsten, W26+. The spectrum was recorded at the Shanghai permanentmagnet electron beam ion trap in the visible region. The identifications were supported by large-scale multiconfiguration Dirac-Hartree-Fock calculations which involved careful inves
Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the
This paper reports on multiconfiguration Dirac-Hartree-Fock calculations for intercombination lines in highly charged silicon-like ions. Results for wavelengths, fine structure, transition rates, branching ratios and lifetimes are reported and compared with other theories and experiments. A review of the experimental situation is presented, and deviations from expected smooth trends along the sequ
Observations of the ultra-sharp-lined HgMn star chi Lupi made with the Goddard High Resolution Spectrograph after the Hubble Space Telescope First Servicing Mission display the effect of COSTAR corrective optics upon the spectral resolution of several observing modes. The resolution is restored to levels expected in the absence of the telescope spherical aberration for all observations made throug
About a quarter of all meteorites falling on Earth today originate from the breakup of the L-chondrite parent body similar to 470 Ma ago, the largest documented breakup in the asteroid belt in the past similar to 3 Ga. A window into the flux of meteorites to Earth shortly after this event comes from the recovery of about 100 fossil L chondrites (1-21 cm in diameter) in a quarry of mid-Ordovician l
Theoretical and experimental results for the 2s(2) S-1(0)-2s2p P-3(1) intercombination line in beryllium-like ions are reviewed and revised, and some new data are presented. The uncertainty in the resulting transition rate is estimated, by using convergence of systematic calculations, accuracy of energy properties and theoretical tests, and is used to evaluate the accuracy of present and other cal
We summarize here the results of a major eight-year investigation of the extraordinarily detailed UV spectrum of the sharp-lined, nonmagnetic, main-sequence, chemically peculiar star chi Lupi (B9.5p HgMn + A2 Vm). The UV observations are composed of 345 Angstrom of the spectrum acquired with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope at an average resolutio
Observations of the ultra-sharp-lined, chemically peculiar star chi Lupi taken by the Goddard High Resolution Spectrograph in echelle mode are presented. Thirty-six intervals of the spectral region between 1249 and 2688 Angstrom are covered with resolving powers in the range 75,000-93,000. Line identifications are provided, and the observed spectra are compared with synthetic spectra calculated us
PURPOSE: To study patients treated with panretinal photocoagulation regarding contrast sensitivity and visual recovery time after exposure to glare. METHODS: To compare contrast sensitivity and visual recovery-time after exposure to glare in eyes (n=20) from 20 type 1 diabetic patients treated with panretinal photocoagulation for proliferative retinopathy with eyes (n= 19) from 19 un-treated type
Abundances for the elements W, Os, and Bi are presented for the HgMn star chi Lupi, based upon GHRS echelle-mode spectra and a synthetic spectrum analysis. The tungsten abundance is consistent with a solar-system value while the osmium and bismuth abundances reflect enhancements. With these new data we are able to quantitatively define an abundance peak within the element range Z = 74 through 83.
GHRS observations of chemically peculiar stars have initiated a new project for calculating atomic properties of heavy elements (Z approximate to 80). The method used is based on large-scale, fully relativistic MCDF, and the data involve accurate gf-values, hyperfine structure parameters, and relative isotope shifts.
We present the scattering lengths for the pi-pi processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order. We then combine this calculation with the determination of the parameters from $Ke4 and the masses and decay constants and compare with the results of a dispersive analysis of pi-pi scattering. The comparison indicates a small but nonzero valu
In spite of our current knowledge regarding the biology underlying cancer genesis, reliable methods for the discovery of cancer driver (CD) genes are still in great need. The rather recent incorporation of epigenetic markers to the cancer paradigm has nevertheless opened the door for the development of new computational approaches to the problem. This work is aimed to study the enrichment of cer
