Peat decomposition indicators of two contrasting bogs in the Eastern Alps, Austria

Since carbon (C) in peatlands is labile and sensitive to disturbances, peatlands have the potential to release high C amounts by land use changes and to accelerate global warming. Therefore, adequate peat decomposition indicators (PDI) are necessary to assess the peatland degradation status and potential for CO2 release. In order to assess the peat degradation status of nine sites in Alpine bogs (Enns valley, Austria), we compared PDI of two peat bogs with contrasting land-use histories. The conventional PDI: loss on ignition, bulk density, C:N ratios, water table depths (WTD) were compared with the recently introduced PDI: stable carbon isotope signature (d13C) and nitrogen isotope signature (d15N). The most PDI were different between the two bogs and the study sites with contrasting WTD and degree of peat decomposition. We demonstrated strong relationships and similar depth profiles of variables: Loss of ignition of strongly degraded peat decreases from the acrotelm to the catotelm, but remains stable at less degraded peat. Bulk density generally increases with depth, and was lowest in the acrotelm of the central bog area and highest in the catotelm of the former peat cutting areas. C:N ratios increased slightly with the degree of peat decomposition. d13C and d15N increased from the top to the depths of -24 to -42 cm at all study sites. In the catotelm, dC13 were significantly lower in strongly decomposed peat compared to the less degraded sites. Higher d15N values in acrotelm and catotelm of strongly degraded peat may be evidence for more pronounced N fractionation during decomposition compared to less degraded sites. Decomposers tend to preferably use substances with 12C for respiration, resulting in a relative enrichment of 13C in the residual organic matter. Accordingly, the increase of d13C with depth in the acrotelm in strongly decayed peat may be assigned to 12C loss by respiration

Summary of the CMS Discovery Potential for the MSSM SUSY Higgses

This work summarises the present understanding of the expected MSSM SUSY Higgs reach for CMS. Many of the studies presented here result from detailed detector simulations incorporating final CMS detector design and response. With 30 fb-1 the h -> gamma,gamma and h -> bb channels allow to cover most of the MSSM parameter space. For the massive A,H,H+ MSSM Higgs states the channels A,H -> tau,tau and H+ -> tau,nu turn out to be the most profitable ones in terms of mass reach and parameter space coverage. Consequently CMS has made a big effort to trigger efficiently on taus. Provided neutralinos and sleptons are not too heavy, there is an interesting complementarity in the reaches for A,H -> tau,tau and A,H -> chi,chi.Comment: 19 pages, 27 figure

CO2- und CH4-Gasaustausch zwischen Atmosphäre und typischen Pflanzenzusammensetzungen eines Hochmoores in den Ostalpen, Österreich

Moorökosysteme besitzen die Fähigkeit unter ungestörten Bedingungen enorme Mengen an Kohlenstoff (C) zu binden und stellen mit einer Speicherung von ca. 612 Pg C die effektivsten Kohlenstoffspeicher aller Ökosysteme dar. Über die Auswirkungen zunehmender Moordegradierung auf den C-Haushalt der Moore des Alpenraumes ist wenig bekannt, obgleich diese, aufgrund des deutlich höheren Temperaturanstiegs während des letzten Jahrhunderts, Aufschluss auf mögliche Folgen des sich schnell verändernden globalen Klimas auf den C-Haushalt geben könnten. Das untersuchte 62 ha große Latschenhochmoor befindet sich im steirischen Ennstal in den Ostalpen und ist fast vollständig mit Torfmoosen bewachsen. Wir untersuchten die CO2- und CH4-Flüsse der am häufigsten auftretenden Pflanzenzusammensetzungen mit der dynamischen Haubenmessmethode an vier Standorten mit jeweils drei Replikaten. Die Messungen wurden 2015 und 2016 in repräsentativen jahreszeitlichen Zeiträumen durchgeführt und mit kontinuierlichen CO2- und CH4-Messungen verglichen, die mit der Eddy-Kovarianz-Methode ermittelt wurden. Die CH4-Flüsse variieren stark zwischen den Standorten mit deutlich höheren Freisetzungsraten auf den von Gräsern und kleinwüchsigen Latschen dominierten Flächen des zentralen Moorbereiches, im Vergleich zu den von Besenheide und höheren Latschen besiedelten Standorten. Es sind jahreszeitliche Schwankungen erkennbar, die auf die Nachlieferung von Streu und das Auftreten von Gräsern mit Durchlüftungsgewebe zurückzuführen sind. Die CO2-Flüsse der Standorte unterscheiden sich ebenfalls deutlich voneinander, wobei diese deutlicheren tages- und jahreszeitlichen Schwankungen unterliegen. Die CO2-Fixierung ist für höherwachsende Latschen am höchsten, gefolgt von Besenheide, Gräsern und kleinwüchsigen Latschen. Die Bodenatmung ist stark von der Bodentemperatur abhängig, unterscheidet sich jedoch nicht wesentlich zwischen den Standorten, sodass die Unterschiede im Nettoökosystemaustausch der Standorte auf die Bruttoprimärproduktion zurückführen sind. Diese ist wiederum stark von der Einstrahlung abhängig. Der Vergleich von Dürreperioden mit Zeiträumen höherer Niederschlagssummen und die starke Abhängigkeit der C-Flüsse von meteorologischen Bedingungen unterstützen die Annahme, dass sich verändernde Klimabedingungen gravierend auf den labilen C-Haushalt der Moore auswirken und dementsprechend positive Rückkopplungseffekte auf die Temperaturerwärmung der Atmosphäre nach sich ziehen werden

Gluon-induced W-boson pair production at the LHC

Pair production of W bosons constitutes an important background to Higgs boson and new physics searches at the Large Hadron Collider LHC. We have calculated the loop-induced gluon-fusion process gg -> W*W* -> leptons, including intermediate light and heavy quarks and allowing for arbitrary invariant masses of the W bosons. While formally of next-to-next-to-leading order, the gg -> W*W* -> leptons process is enhanced by the large gluon flux at the LHC and by experimental Higgs search cuts, and increases the next-to-leading order WW background estimate for Higgs searches by about 30%. We have extended our previous calculation to include the contribution from the intermediate top-bottom massive quark loop and the Higgs signal process. We provide updated results for cross sections and differential distributions and study the interference between the different gluon scattering contributions. We describe important analytical and numerical aspects of our calculation and present the public GG2WW event generator.Comment: 20 pages, 4 figure

NLO QCD corrections to hadronic Higgs production with heavy quarks

The production of a Higgs boson in association with a pair of top-antitop or bottom-antibottom quarks plays a very important role at both the Tevatron and the Large Hadron Collider. The theoretical prediction of the corresponding cross sections has been improved by including the complete next-to-leading order QCD corrections. After a brief description of the most relevant technical aspects of the calculation, we review the results obtained for both the Tevatron and the Large Hadron ColliderComment: 6 pages, 6 figures, espcrc2.sty. Talk given at the International Conference QCD03, 2-7 July 2003, Montpellier, France. To be published in Nucl. Phys. B Proc. Supp

pp -> ttH, H->tau tau: toward a model independent determination of the Higgs boson couplings at the LHC

The possibility of detecting a Higgs boson through several production and decay channels is instrumental to the measurement of its couplings. In this paper we study the pp-> ttH(H-> tau tau) channel at the LHC, for the case of a scalar Higgs boson, and use the obtained results to improve on existing strategies toward a model independent determination of the Higgs boson couplings. The case of a scalar Higgs boson with mass below 140 GeV looks particularly promising.Comment: 19 pages, 5 Figures, LaTex, published version, typos corrected, comments added in Sec.

NLO QCD corrections to pp -> ttbb+X via quark anti-quark annihilation

The process pp -> top anti-top bottom anti-bottom + X represents a very important background reaction to searches at the LHC, in particular to top anti-top H production where the Higgs boson decays into a bottom anti-bottom pair. A successful analysis of top anti-top H at the LHC requires the knowledge of direct top anti-top bottom anti-bottom production at NLO in QCD. We take the first step in this direction upon calculating the NLO QCD corrections to the subprocess initiated by quark anti-quark annihilation.Comment: 6 pages, LaTeX, 4 postscript figures, to appear in proceedings of the "9th Workshop on Elementary Particle Theory: Loops and Legs in Quantum Field Theory", Sondershausen, Germany, April 20-25, 200

Dominant next-to-leading order QCD corrections to Higgs plus three jet production in vector-boson fusion

We present the calculation of the dominant next to leading order QCD corrections to Higgs boson production in association with three jets via vector boson fusion in the form of a NLO parton-level Monte Carlo program. QCD corrections to integrated cross sections are modest, while the shapes of some kinematical distributions change appreciably at NLO. Scale uncertainties are shown to be reduced at NLO for the total cross section and for distributions. We consider a central jet veto at the LHC and analyze the veto probability for typical vector boson fusion cuts. Scale uncertainties of the veto probability are sufficiently small at NLO for precise Higgs coupling measurements at the LHC.Comment: 40 pages, 17 figures, 2 tables, published versio

Measuring the Higgs Sector

If we find a light Higgs boson at the LHC, there should be many observable channels which we can exploit to measure the relevant parameters in the Higgs sector. We use the SFitter framework to map these measurements on the parameter space of a general weak-scale effective theory with a light Higgs state of mass 120 GeV. Our analysis benefits from the parameter determination tools and the error treatment used in new--physics searches, to study individual parameters and their error bars as well as parameter correlations.Comment: 45 pages, Journal version with comments from refere