249 research outputs found
Complete Corrections of O(\alpha\alpha_s) to the Decay of the Z Boson into Bottom Quarks
For the vertex corrections to the partial decay rate
involving the top quark only the leading terms of order in the
expansion are known. In this work we compute the missing
next-to-leading corrections. Thus at the complete
corrections to the decay of the Z boson into bottom quarks are at hand.Comment: Latex, 11 pages, 1 figure included as ps-file. Two references
changed. The complete paper is also available via anonymous ftp at
ftp://ttpux2.physik.uni-karlsruhe.de/ttp97/ttp97-52/ or via www at
http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints
Nest Site Characteristics and Breeding Biology of Flammmulated Owls in Missoula Valley
Seidensticker, Mathew, M.S., Spring 2011 Environmental Studies Nest Sites and Breeding Biology of Flammulated Owls in Missoula Valley Chairperson: Len Broberg The Flammulated Owl is listed as a sensitive or species of concern with United States Forest Service, Bureau of Land Management, and Montana Fish, Wildlife and Parks. Despite these listings the Flammulated Owl is little studied in Montana. Although region-wide surveys have greatly increased our understanding of distribution and landscape level habitat associations of Flammulated Owls, information about breeding is lacking. In order to address this need for breeding information I searched for and quantified nest site characteristics and breeding biology of Flammulated Owls in Missoula Valley from 2008-2010. I located 17 Flammulated Owl territories, four nests, and banded 12 individuals. I also utilized radio telemetry to help gather information about roosting and foraging habitat. Although our sample size is limited, nest site characteristics and breeding parameters in my study were within the range of information published by other authors for Flammulated Owl nests. Much more information about Flammulated Owl breeding biology is needed to comprehensively assess the status of this owl species and build scientifically responsible models for managing habitat in Montana
Dimensional Reduction applied to QCD at three loops
Dimensional Reduction is applied to \qcd{} in order to compute various
renormalization constants in the \drbar{} scheme at higher orders in
perturbation theory. In particular, the function and the anomalous
dimension of the quark masses are derived to three-loop order. Special emphasis
is put on the proper treatment of the so-called -scalars and the
additional couplings which have to be considered.Comment: 13 pages, minor changes, references adde
The four-loop DRED gauge beta-function and fermion mass anomalous dimension for general gauge groups
We present four-loop results for the gauge beta-function and the fermion mass
anomalous dimension for a gauge theory with a general gauge group and a
multiplet of fermions transforming according to an arbitrary representation,
calculated using the dimensional reduction scheme. In the special case of a
supersymmetric theory we confirm previous calculations of both the gauge
beta-function and the gaugino mass beta-function.Comment: 44 pages, added references (v2) minor changes (v3
Two-loop parameter relations between dimensional regularization and dimensional reduction applied to SUSY-QCD
The two-loop relations between the running gluino-quark-squark coupling, the
gluino and the quark mass defined in dimensional regularization (DREG) and
dimensional reduction (DRED) in the framework of SUSY-QCD are presented.
Furthermore, we verify with the help of these relations that the three-loop
beta-functions derived in the minimal subtraction scheme combined with DREG or
DRED transform into each other. This result confirms the equivalence of the two
schemes through three-loops, if applied to SUSY-QCD.Comment: 14 pages, Latex; v2 matches published versio
Strong-Coupling Constant at Three Loops in Momentum Subtraction Scheme
In this paper we compute the three-loop corrections to the function
in a momentum subtraction (MOM) scheme with a massive quark. The calculation is
performed in the background field formalism applying asymptotic expansions for
small and large momenta. Special emphasis is devoted to the relation between
the coupling constant in the MOM and schemes as well as
their ability to describe the phenomenon of decoupling.
It is demonstrated by an explicit comparison that the
scheme can be consistently used to relate the values of the MOM-scheme
strong-coupling constant in the energy regions higher and lower than the
massive-quark production threshold. This procedure obviates the necessity to
know the full mass dependence of the MOM function and clearly
demonstrates the equivalence of both schemes for the description of physics
outside the threshold region.Comment: 17 pages, 5 figure
Four-Loop Decoupling Relations for the Strong Coupling
We compute the matching relation for the strong coupling constant within the
framework of QCD up to four-loop order. This allows a consistent five-loop
running (once the function is available to this order) taking into
account threshold effects. As a side product we obtain the effective coupling
of a Higgs boson to gluons with five-loop accuracy.Comment: 11 page
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