28894742
Mass effects in muon and semileptonic b-->c decays.
Quantum chromodynamics (QCD) effects in the semileptonic decay b-->clnu are evaluated to the second order in the coupling constant, O(alpha(s){2}), and to several orders in the expansion in quark masses, m{c}/m{b}. Corrections are calculated for the total decay rate as well as for the first two moments of the lepton energy and the hadron system energy distributions. Translated into QED and applied to the muon decay, they decrease its predicted rate by -0.43 ppm.
119160611
Heavy-to-heavy quark decays at NNLO
X iv :0 80 8. 35 09 v1 [ he pph ] 2 6 A ug 2 00 8 Alberta Thy 10-08 Heavy-to-heavy quark de ays at NNLO Alexey Pak and Andrzej Czarne ki Department of Physi s, University of Alberta, Edmonton, AB, T6G 2G7, Canada Details of a re ent al ulation of O`αs ́ orre tions to the de ay b → clνl, taking into a ount the c-quark mass, are des ribed. Constru tion of the expansion in the mass ratio mc/mb as well as the evaluation of new four-loop master integrals are presented. The same te hniques are appli able to the muon de ay, μ → eνμν̄e. Analyti al results are presented, for the physi al ases as well as for a model with purely-ve tor ouplings.
118642041
PUZZLING b QUARK DECAYS: HOW TO ACCOUNT FOR THE CHARM MASS∗
For more than a decade, measurements of the semileptonic branching ratio of hadrons containing a b quark disagreed with the Standard Model predictions. Very recently, a class of strong-interaction effects was found to significantly increase the non-leptonic b decay rate and thus bring the Standard Model prediction into agreement with the experiment. Final state charm quark mass effects should be determined to refine the theoretical description of b decays. Prospects for such improvement are discussed in this talk.
118643333
Finite top quark mass effects in NNLO Higgs boson production at LHC
We present next-to-next-to-leading order corrections to the inclusive production of the Higgs bosons at the CERN Large Hadron Collider (LHC) including finite top quark mass effects. Expanding our analytic results for the partonic cross section around the soft limit we find agreement with a very recent publication by Harlander and Ozeren [1].
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.
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.
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.
11310446
Measurements of an ablator-gas atomic mix in indirectly driven implosions at the National Ignition Facility.
We present the first results from an experimental campaign to measure the atomic ablator-gas mix in the deceleration phase of gas-filled capsule implosions on the National Ignition Facility. Plastic capsules containing CD layers were filled with tritium gas; as the reactants are initially separated, DT fusion yield provides a direct measure of the atomic mix of ablator into the hot spot gas. Capsules were imploded with x rays generated in hohlraums with peak radiation temperatures of ∼294  eV. While the TT fusion reaction probes conditions in the central part (core) of the implosion hot spot, the DT reaction probes a mixed region on the outer part of the hot spot near the ablator-hot-spot interface. Experimental data were used to develop and validate the atomic-mix model used in two-dimensional simulations.
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
118588757
Generalization of the Andersson-Otterlund-Stenlund model for description of slow particle yield in interactions of nuclei with photoemulsion nuclei