Measurement of Magnesium Oxide Sputtering Yields by He and Ar Ions with a Low-Energy Mass-Selected Ion Beam System

Abstract

We consider QCD corrections to Higgs boson production through gluon-gluon fusion in hadron collisions. Using the recently evaluated [14] two-loop amplitude for this process and the corresponding factorization formulae [15]-[18] describing soft-gluon bremsstrahlung at O(α 2 S ), we compute the soft and virtual contributions to the next-to-next-to-leading order cross section. We also discuss soft-gluon resummation at next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson production at the LHC are presented. ‡ Partially supported by Fundación Antorchas JHEP05(2001)025exceeds all the other production channels by a factor decreasing from 8 to 5 when M H increases from 100 to 200 GeV. When M H approaches 1 TeV, gg fusion still provides about 50% of the total production cross section.QCD radiative corrections at next-to-leading order (NLO) to gg-fusion were computed and found to be large [10]- [12]. Since approximate evaluations [13] of higher-order terms suggest that their effect can still be sizeable, the evaluation of the next-to-next-to-leading order (NNLO) corrections is highly desirable.In this paper, we perform a first step towards the complete NNLO calculation. We use the recently evaluated [14] two-loop amplitude for the process gg → H and the soft-gluon factorization formulae [15]-[18] for the bremsstrahlung subprocesses gg → Hg and gg → Hgg, Hqq, and we compute the soft and virtual contributions to the NNLO partonic cross section. We also discuss all-order resummation of soft-gluon contributions to next-to-next-to-leading logarithmic (NNLL) accuracy.We use the approximation M t M H , where M t is the mass of the top quark. The results of the NLO calculation in ref. [12] show that this is a good numerical approximation [13] of the full NLO correction, provided the exact dependence on M H /M t is included in the leading-order (LO) term. We can thus assume that the limit M t M H continues to be a good numerical approximation at NNLO. The hadronic cross section for Higgs boson production is obtained by convoluting the perturbative partonic cross sections with the parton distributions of the colliding hadrons. Besides the partonic cross sections, the other key ingredients of the NNLO calculation are the NNLO parton distributions. Even though their NNLO evolution kernels are not fully available, some of their Mellin moments have been computed [19] and, from these, approximated kernels have been constructed [20]. Recently, the new MRST [21] sets of distributions became available 1 , including the (approximated) NNLO densities, which allows an evaluation of the hadronic cross section to (almost full) NNLO accuracy.We use our NNLO result for the partonic cross sections and the MRST parton distributions at NNLO to compute the Higgs boson production cross section at the LHC. In this paper, we do not present numerical results for Run II at the Tevatron. Inclusive production of Higgs boson through gluon-gluon fusion is phenomenologically less relevant at the Tevatron: it is not regarded as a main ...

Low Energy Metal Ion Beam Production with a Modified Freeman-Type Ion Source for Development of Novel Catalysts

“…The film mass change on the QCM crystal can be monitored by a QCM controller (ULVAC-CRTM9000). The mass resolution of the QCM system is 2.4×10 −11 g. With this QCM system, we have measured sputtering yields of Au [8] and magnesium oxide (MgO) [9,10] by He, Ne, Ar, Kr, or Xe ion beams and found that the measured sputtering yields agree well with earlier data obtained by other experimental groups.…”

Experimental evaluation of MgO sputtering yields by monochromatic Ne, Kr, or Xe ion beams

“…For example, experimentally obtained MgO sputtering yield data for He and Ar ion injections in the energy range below about 500 eV have been presented recently by the authors of this article [2]. Other experimentally measured sputtering yields of MgO by low-energy noble gas ions that we are aware of are only those presented in Refs.…”

“…[5] do not agree with published experimental data of Refs. [2][3][4]. No experimentally measured or theoretically estimated MgO sputtering yields by Kr ion bombardment in the low-energy range seem to have been reported so far.…”

Observations of metallic species in Mercury’s exosphere

“…Sputter yields of Mg from MgO by low-energy He and Ar ion beams were measured as a function of ion energy by Hine et al (2007) and fit to the following equations:…”