119359676
MONTE-CARLO SIMULATION OF EXCLUSIVE CHANNELS IN e + e ANNIHILATION AT LOW ENERGY
Software package for Monte-Carlo simulation of e + e exclusive annihilation channels written in the C++ language for Linux/Solaris platforms has been developed. It incorporates matrix elements for several mechanisms of multipion production in a model of consequent two and three-body resonance decays. Possible charge states of intermediate and nal particles are accounted automatically under the assumption of isospin conservation. Interference eects can be taken into acccount. Package structure allows adding new matrix elements written in a gauge-invariant form.
16606377
Virtual three-loop corrections to Higgs boson production in gluon fusion for finite top quark mass
Abstract In this Letter we present the three-loop virtual corrections to the Higgs boson production in the gluon fusion channel where finite top quark mass effects are taken into account. We perform an asymptotic expansion and manage to evaluate five terms in the expansion parameter M H 2 / M t 2 . A good convergence is observed almost until M H ≈ 2 M t .
17701283
Large mass expansion in two-loop QCD corrections of paracharmonium decay
We calculate the two-loop QCD corrections to paracharmonium decays {eta}{sub c}{yields}{gamma}{gamma} and {eta}{sub c}{yields}gg involving light-by-light scattering diagrams with light quark loops. Artificial large mass expansion and convergence improvement techniques are used to evaluate these corrections. The obtained corrections to the decays {eta}{sub c}{yields}{gamma}{gamma} and {eta}{sub c}{yields}gg account for -1.25% and -0.73% of the leading order contribution, respectively.
17926378
Towards Higgs boson production in gluon fusion to NNLO in the MSSM
We consider the Higgs boson production in the gluon-fusion channel to next-to-next-to-leading order within the Minimal Supersymmetric Standard Model. In particular, we present analytical results for the matching coefficient of the effective theory and study its influence on the total production cross section in the limit where the masses of all MSSM particles coincide. For supersymmetric masses below 500 GeV it is possible to find parameters leading to a significant enhancement of the Standard Model cross section, the K-factors, however, change only marginally.
118453849
The toolbox of modern multi-loop calculations: novel analytic and semi-analytic techniques
We describe three algorithms for computer-aided symbolic multi-loop calculations that facilitated some recent novel results. First, we discuss an algorithm to derive the canonical form of an arbitrary Feynman integral in order to facilitate their identification. Second, we present a practical solution to the problem of multi-loop analytical tensor reduction. Finally, we discuss the partial fractioning of polynomials with external linear relations between the variables. All algorithms have been tested and used in real calculations.
15576012
Higgs boson production at the LHC: NNLO partonic cross sections through order $\epsilon$ and convolutions with splitting functions to N$^3$LO
We consider Higgs boson production at hadron colliders in the gluon fusion channel and compute higher order terms in the regularization parameter ǫ. In particular, the next-to-next-to-leading order cross section is evaluated including order ǫ terms. These results are used to compute all convolutions with the splitting functions entering the next-to-next-to-next-to-leading order cross section.
12050133
Angular dependence of betatron x-ray spectra from a laser-wakefield accelerator.
We present the first measurements of the angular dependence of the betatron x-ray spectrum produced by electrons inside the cavity of a laser-wakefield accelerator. Electrons accelerated up to 300 MeV energies produce a beam of broadband, forward-directed betatron x-ray radiation extending up to 80 keV. The angular resolved spectrum from an image plate-based spectrometer with differential filtering provides data in a single laser shot. The simultaneous spectral and spatial x-ray analysis allows for a three-dimensional reconstruction of electron trajectories with micrometer resolution, and we find that the angular dependence of the x-ray spectrum is showing strong evidence of anisotropic electron trajectories.
181813172
CHARACTERISTIC FUNCTIONS OF INCLUSIVE PROCESSES WITH THE PARTICIPATION OF LIGHT NUCLEI
4466026
Fuel gain exceeding unity in an inertially confined fusion implosion
Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium–tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a ‘high-foot’ implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium–tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the ‘bootstrapping’ required to accelerate the deuterium–tritium fusion burn to eventually ‘run away’ and ignite.
118588757
Generalization of the Andersson-Otterlund-Stenlund model for description of slow particle yield in interactions of nuclei with photoemulsion nuclei