26 research outputs found
Electroweak corrections in the 2HDM for neutral scalar Higgs-boson production through gluon fusion
We have computed the two-loop, electroweak corrections to the production of a
light and a heavy neutral, scalar Higgs-boson through the important gluon
fusion process in the Two-Higgs-Doublet Model. We provide our results in
various renormalization schemes for different scenarios and benchmark points,
which will be valuable for experimental studies at the LHC. We describe the
technicalities of our two-loop calculation and augment it by a phenomenological
discussion. Our results are also applicable to the gluonic neutral, scalar
Higgs-boson decays.Comment: 36 pages, 11 figures, 8 tables, v2: version accepted for publication
in the journa
Radiative distortion of kinematic edges in cascade decays
Kinematic edges of cascade decays of new particles produced in high-energy
collisions may provide important constraints on the involved particles' masses.
For the exemplary case of gluino decay into
a pair of quarks and a neutralino through a squark resonance, we study the
hadronic invariant mass distribution in the vicinity of the kinematic edge. We
perform a next-to-leading order calculation in the strong coupling
and the ratio of squark width and squark mass \Gamma_\tilde{q}/m_\tilde{q},
based on a systematic expansion in \Gamma_\tilde{q}/m_\tilde{q}. The
separation into hard, collinear and soft contributions elucidates the process
dependent and universal features of distributions in the edge region,
represented by on-shell decay matrix elements, universal jet functions and a
soft function that depends on the resonance propagator and soft Wilson lines.Comment: 15 pages, 5 figure
An extensive survey of the estimation of uncertainties from missing higher orders in perturbative calculations
We consider two approaches to estimate and characterise the theoretical
uncertainties stemming from the missing higher orders in perturbative
calculations in Quantum Chromodynamics: the traditional one based on
renormalisation and factorisation scale variation, and the Bayesian framework
proposed by Cacciari and Houdeau. We estimate uncertainties with these two
methods for a comprehensive set of more than thirty different observables
computed in perturbative Quantum Chromodynamics, and we discuss their
performance in properly estimating the size of the higher order terms that are
known. We find that scale variation with the conventional choice of varying
scales within a factor of two of a central scale gives uncertainty intervals
that tend to be somewhat too small to be interpretable as 68%
confidence-level-heuristic ones. We propose a modified version of the Bayesian
approach of Cacciari and Houdeau which performs well for non-hadronic
observables and, after an appropriate choice of the relevant expansion
parameter for the perturbative series, for hadronic ones too.Comment: 34 pages, 24 figure
Gauge-independent renormalization in the 2HDM
We present a consistent renormalization scheme for the CP-conserving
Two-Higgs-Doublet Model based on renormalization of the mixing
angles and the soft--symmetry-breaking scale in the Higgs sector.
This scheme requires to treat tadpoles fully consistently in all steps of the
calculation in order to provide gauge-independent -matrix elements. We show
how bare physical parameters have to be defined and verify the gauge
independence of physical quantities by explicit calculations in a general
-gauge. The procedure is straightforward and applicable to other
models with extended Higgs sectors. In contrast to the proposed scheme, the
renormalization of the mixing angles combined with popular
on-shell renormalization schemes gives rise to gauge-dependent results already
at the one-loop level. We present explicit results for electroweak NLO
corrections to selected processes in the appropriately renormalized
Two-Higgs-Doublet Model and in particular discuss their scale dependence.Comment: 52 pages, PDFLaTeX, PDF figures, JHEP version with Eq. (5.23)
correcte
Russland, Indien, China ein neues strategisches Dreieck?
UuStB Koeln(38)-940106459 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
A high-resolution transcriptome map identifies small RNA regulation of metabolism in the gut microbe Bacteroides thetaiotaomicron.
Bacteria of the genus Bacteroides are common members of the human intestinal microbiota and important degraders of polysaccharides in the gut. Among them, the species Bacteroides thetaiotaomicron has emerged as the model organism for functional microbiota research. Here, we use differential RNA sequencing (dRNA-seq) to generate a single-nucleotide resolution transcriptome map of B. thetaiotaomicron grown under defined laboratory conditions. An online browser, called 'Theta-Base' ( www.helmholtz-hiri.de/en/datasets/bacteroides ), is launched to interrogate the obtained gene expression data and annotations of ~4500 transcription start sites, untranslated regions, operon structures, and 269 noncoding RNA elements. Among the latter is GibS, a conserved, 145 nt-long small RNA that is highly expressed in the presence of N-acetyl-D-glucosamine as sole carbon source. We use computational predictions and experimental data to determine the secondary structure of GibS and identify its target genes. Our results indicate that sensing of N-acetyl-D-glucosamine induces GibS expression, which in turn modifies the transcript levels of metabolic enzymes