1,253 research outputs found
NLO QCD bottom corrections to Higgs boson production in the MSSM
We present a calculation of the two-loop bottom-sbottom-gluino contributions
to Higgs boson production via gluon fusion in the MSSM. The calculation is
based on an asymptotic expansion in the masses of the supersymmetric particles,
which are assumed to be much heavier than the bottom quark and the Higgs
bosons. We obtain explicit analytic results that allow for a straightforward
identification of the dominant contributions in the NLO bottom corrections. We
emphasize the interplay between the calculations of the masses and the
production cross sections of the Higgs bosons, discussing sensible choices of
renormalization scheme for the parameters in the bottom/sbottom sector.Comment: 25 pages, 4 figures. v2: references and two figures added, version
published in JHE
(Il)Legitimisation of the role of the nation state: Understanding of and reactions to Internet censorship in Turkey
This study aims to explore Turkish citizen-consumers' understanding of and reactions to censorship of websites in Turkey by using in-depth interviews and online ethnography. In an environment where sites such as YouTube and others are increasingly being banned, the citizen-consumers' macro-level understanding is that such censorship is part of a wider ideological plan and their micro-level understanding is that their relationship with the wider global network is reduced, in the sense that they have trouble accessing full information on products, services and experiences. The study revealed that citizen-consumers engage in two types of resistance strategies against such domination by the state: using irony as passive resistance, and using the very same technology used by the state to resist its domination
NLO QCD corrections to pseudoscalar Higgs production in the MSSM
We present a calculation of the two-loop quark-squark-gluino contributions to
pseudoscalar Higgs boson production via gluon fusion in the MSSM. We regularize
the loop integrals using the Pauli-Villars method, and obtain explicit and
compact analytic results based on an expansion in the heavy particle masses.
Our results - valid when the pseudoscalar Higgs boson is lighter than squarks
and gluinos - can be easily implemented in computer codes for an efficient and
accurate determination of the pseudoscalar production cross section.Comment: 26 pages, 4 figures. v2: comments added in section 3, version
published in JHE
Who bullies whom at a garden feeder? Interspecific agonistic interactions of small passerines during a cold winter
Interspecific agonistic interactions are important
selective factors for maintaining ecological niches of
different species, but their outcome is difficult to predict
a priori. Here, we examined the direction and intensity of
interspecific interactions in an assemblage of small passerines
at a garden feeder, focussing on three finch species
of various body sizes. We found that large and mediumsized
birds usually initiated and won agonistic interactions
with smaller species. Also, the frequency of fights increased
with decreasing differences in body size between
the participants. Finally, the probability of engaging in a
fight increased with the number of birds at the feeder
Properties of 125 GeV Higgs boson in non-decoupling MSSM scenarios
Tantalizing hints of the Higgs boson of mass around 125 GeV have been
reported at the LHC. We explore the MSSM parameter space in which the 125 GeV
state is identified as the heavier of the CP even Higgs bosons, and study two
scenarios where the two photon production rate can be significantly larger than
the standard model (SM). In one scenario, is
enhanced by a light stau contribution, while the () rate
stays around the SM rate. In the other scenario, is
suppressed and not only the but also the
() rates should be enhanced. The rate can be
significantly larger or smaller than the SM rate in both scenarios. Other
common features of the scenarios include top quark decays into charged Higgs
boson, single and pair production of all Higgs bosons in collisions at
GeV.Comment: 20 pages, 5 figures, accepted version for publication in JHE
How did the toad get over the sea to Skye? Tracing the colonisation of Scottish inshore islands by common toads (Bufo bufo)
Processes of island colonisation have long been of interest to biologists. Colonisation events themselves are rarely observed, but the processes involved may be inferred using genetic approaches. We investigated possible means of island colonisation by common toads (Bufo bufo) in western Scotland (the Isle of Skye and five neighbouring small islands), using evidence derived from nuclear microsatellites and mitochondrial (mt) DNA. Levels of microsatellite allelic richness for populations on Skye were high and comparable to adjacent mainland populations, but lower for populations on small islands. Pairwise measures of genetic distances between populations and a clustering algorithm were both suggestive of frequent gene flow between Skye and the mainland. For small islands the levels of genetic differentiation were higher, implying stronger isolation and no evidence for inbreeding. The distribution of mtDNA haplotypes broadly mirrored the genetic structure revealed by microsatellites. Reconciled with existing palaeoclimatological evidence, since the last glaciation, our findings rule out the possibility that the B. bufo populations stem from glacial refugia, or that recent anthropogenic transfer of toads is responsible for their current distribution. The most parsimonious explanation of our data is that the studied inshore islands have been repeatedly colonised via rafting from the mainland or neighbouring islands. This may give us insights into the processes likely to take place when ice sheets retreat poleward as a result of climate change. It also has implications for the colonisation of
both native and invasive non-native species, and hence the biosecurity of island refugia
Supersymmetric Higgs Yukawa Couplings to Bottom Quarks at next-to-next-to-leading Order
The effective bottom Yukawa couplings are analyzed for the minimal
supersymmetric extension of the Standard Model at two-loop accuracy within
SUSY-QCD. They include the resummation of the dominant corrections for large
values of tg(beta). In particular the two-loop SUSY-QCD corrections to the
leading SUSY-QCD and top-induced SUSY-electroweak contributions are addressed.
The residual theoretical uncertainties range at the per-cent level.Comment: 25 pages, 9 figures, added comments and references, typos corrected,
results unchanged, published versio
Higgs production via gluon fusion in the POWHEG approach in the SM and in the MSSM
We consider the gluon fusion production cross section of a scalar Higgs boson
at NLO QCD in the SM and in the MSSM. We implement the calculation in the
POWHEG approach, and match the NLO-QCD results with the PYTHIA and HERWIG QCD
parton showers. We discuss a few representative scenarios in the SM and MSSM
parameter spaces, with emphasis on the fermion and squark mass effects on the
Higgs boson distributions.Comment: 27 pages, 36 eps figures; v2: 2 eps figures added, section 3.2
expanded, version published in JHE
Genetic diversity of Brazilian isolates of feline immunodeficiency virus
We isolated Feline immunodeficiency virus (FIV) from three adult domestic cats, originating from two open shelters in Brazil. Viruses were isolated from PBMC following co-cultivation with the feline T-lymphoblastoid cell line MYA-1. All amplified env gene products were cloned directly into pGL8MYA. The nucleic acid sequences of seven clones were determined and then compared with those of previously described isolates. The sequences of all of the Brazilian virus clones were distinct and phylogenetic analysis revealed that all belong to subtype B. Three variants isolated from one cat and two variants were isolated from each of the two other cats, indicating that intrahost diversity has the potential to pose problems for the treatment and diagnosis of FIV infection
Preventing phone theft and robbery: the need for government action and international coordination
The banning of stolen handsets from networks has been around for 20 years, but remains little used internationally. Where used, its effectiveness is hindered by implementation problems, reprogramming, easy fencing opportunities, and international trafficking. Kill-switches where the user remotely disables a handset and deletes data have potential but, if non-permanent, are likely to experience similar limitations. This study proposes a set of responses to be adopted by national governments with international coordination
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