Search results for "Nuclear and high energy physics"
showing 10 items of 8241 documents
Performance of jet substructure techniques for large-$R$ jets in proton-proton collisions at $\sqrt{s}$ = 7 TeV using the ATLAS detector
2013
This paper presents the application of a variety of techniques to study jet substructure. The performance of various modified jet algorithms, or jet grooming techniques, for several jet types and event topologies is investigated for jets with transverse momentum larger than 300 GeV. Properties of jets subjected to the mass-drop filtering, trimming, and pruning algorithms are found to have a reduced sensitivity to multiple proton-proton interactions, are more stable at high luminosity and improve the physics potential of searches for heavy boosted objects. Studies of the expected discrimination power of jet mass and jet substructure observables in searches for new physics are also presented.…
Optimized Multipactor-Resistant Wedge-Shaped Waveguide Bandpass Filters
2013
[EN] Wedge-shaped waveguides present a certain advantage with respect to rectangular waveguides regarding their resistance to multipactor discharges. In this paper, the optimal configuration for the wedge geometry is investigated based on theoretical results, on a precise multipactor prediction tool, and on previous experience. In addition, design rules are presented, which allow us to achieve for wedge-shaped filters electrical performances comparable to the ones of rectangular waveguide filters, while at the same time improving the multipactor-free power range. As a proof of concept, two three-pole bandpass filters with equivalent electrical characteristic of 150-MHz bandwidth, centered a…
Explanation of theΔ5/2−(1930)as aρΔbound state
2009
We use the $\ensuremath{\rho}\ensuremath{\Delta}$ interaction in the hidden gauge formalism to dynamically generate ${N}^{*}$ and ${\ensuremath{\Delta}}^{*}$ resonances. We show, through a comparison of the results from this analysis and from a quark model study with data, that the ${\ensuremath{\Delta}}_{5/{2}^{\ensuremath{-}}}(1930)$, ${\ensuremath{\Delta}}_{3/{2}^{\ensuremath{-}}}(1940)$, and ${\ensuremath{\Delta}}_{1/{2}^{\ensuremath{-}}}(1900)$ resonances can be assigned to $\ensuremath{\rho}\ensuremath{\Delta}$ bound states. More precisely the ${\ensuremath{\Delta}}_{5/{2}^{\ensuremath{-}}}(1930)$ can be interpreted as a $\ensuremath{\rho}\ensuremath{\Delta}$ bound state whereas the $…
Measurement of the branching fraction forB±→χc0K±
2004
We present a measurement of the branching fraction of the decay ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\chi}}_{c0}{K}^{\ifmmode\pm\else\textpm\fi{}}$ from a sample of $89\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. The ${\ensuremath{\chi}}_{c0}$ meson is reconstructed through its two-body decays to ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${K}^{+}{K}^{\ensuremath{-}}.$ We measure $\mathcal{B}{(B}^{\ifmmode\pm\else\textpm\fi{}}\stackrel{\ensuremath{\rightarrow}}{}{\ensuremath{\chi}}_{c0}{K}^{\ifmmode\pm\else\textpm\fi{}})\ifmmode\times\e…
Novel patterns for vector mesons from the large-Nc limit
2008
We report on a relation between the decay constants of \rho-like J^{PC}=1^{--} vector mesons, which arises solely from the perturbative analysis of the VV, TT and VT correlators at order \alpha_s^0 in the large-N_c limit. We find f_{V}^T/f_{V}=1/\sqrt{2} for highly excited states together with a pattern of alternation in sign. Quite remarkably, recent lattice determinations reported f_{\rho}^T/f_{\rho}=0.72(2), in excellent agreement with our large-N_c result. This seems to suggest a pattern like f_{Vn}^T/f_{Vn}=(-1)^n/\sqrt{2} for the whole (1^{--}) states. In order to test this conjecture in real QCD we construct a set of spectral sum rules, which turn out to comply nicely with this scena…
SELF-ENERGIES AND VERTEX CORRECTIONS WITH TWO FACTORIZING LOOPS
1999
A complete set of factorizing two-loop self-energies and vertex corrections is calculated analytically for arbitrary masses and momenta — including the case of collinear singularities — within the ℛ-functions approach.
Neutral-Current Neutrino-Nucleus Scattering off Xe Isotopes
2018
Large liquid xenon detectors aiming for dark matter direct detection will soon become viable tools also for investigating neutrino physics. Information on the effects of nuclear structure in neutrino-nucleus scattering can be important in distinguishing neutrino backgrounds in such detectors. We perform calculations for differential and total cross sections of neutral-current neutrino scattering off the most abundant xenon isotopes. The nuclear structure calculations are made in the nuclear shell model for elastic scattering, and also in the quasiparticle random-phase approximation (QRPA) and microscopic quasiparticle phonon model (MQPM) for both elastic and inelastic scattering. Using suit…
Ab initio modeling of oxygen impurity atom incorporation into uranium mononitride surface and subsurface vacancies
2011
The incorporation of oxygen atoms has been simulated into either nitrogen or uranium vacancy at the UN(001) surface, sub-surface or central layers. For calculations on the corresponding slab models both the relativistic pseudopotentials and the method of projector augmented-waves (PAW) as implemented in the VASP computer code have been used. The energies of O atom incorporation and solution within the defective UN surface have been calculated and discussed. For different configurations of oxygen ions at vacancies within the UN(001) slab, the calculated density of states and electronic charge re-distribution was analyzed. Considerable energetic preference of O atom incorporation into the N-v…
Chemisorption of a molecular oxygen on the UN(001) surface: Ab initio calculations
2010
The results of DFT GGA calculations on oxygen molecules adsorbed upon the (0 0 1) surface of uranium mononitride (UN) are presented and discussed. We demonstrate that O2 molecules oriented parallel to the substrate can dissociate either (i) spontaneously when the molecular center lies above the surface hollow site or atop N ion, (ii) with the activation barrier when a molecule sits atop the surface U ion. This explains fast UN oxidation in air.
Calculations of radiation-induced point defects, polarons and excitons in ferroelectric perovskites
2002
Abstract We review results of our recent large-scale computer simulations of radiation-induced point defects, excitons and polarons in ABO3 perovskite crystals, focusing mostly on KNbO3 and KTaO3 as representative examples. We have calculated the atomic and electronic structure of defects, their optical absorption, defect-induced electron density redistribution, and activation energies for defect migration. The majority of our results were obtained using the quantum-chemical method of the intermediate neglect of differential overlap (INDO) based on the Hartree–Fock formalism, as well as the shell model (SM). The main findings are compared with those obtained by means of ab initio density fu…