198 research outputs found
Production of tau tau jj final states at the LHC and the TauSpinner algorithm: the spin-2 case
The TauSpinner algorithm is a tool that allows to modify the physics model of
the Monte Carlo generated samples due to the changed assumptions of event
production dynamics, but without the need of re-generating events. With the
help of weights -lepton production or decay processes can be modified
accordingly to a new physics model. In a recent paper a new version TauSpinner
ver.2.0.0 has been presented which includes a provision for introducing
non-standard states and couplings and study their effects in the
vector-boson-fusion processes by exploiting the spin correlations of
-lepton pair decay products in processes where final states include also
two hard jets. In the present paper we document how this can be achieved taking
as an example the non-standard spin-2 state that couples to Standard Model
particles and tree-level matrix elements with complete helicity information
included for the parton-parton scattering amplitudes into a -lepton pair
and two outgoing partons. This implementation is prepared as the external (user
provided) routine for the TauSpinner algorithm. It exploits amplitudes
generated by MadGraph5 and adopted to the TauSpinner algorithm format.
Consistency tests of the implemented matrix elements, reweighting algorithm and
numerical results for observables sensitive to polarization are
presented.Comment: 17 pages, 6 figures; version published in EPJ
Kinematically Redundant Octahedral Motion Platform for Virtual Reality Simulations
We propose a novel design of a parallel manipulator of Stewart Gough type for
virtual reality application of single individuals; i.e. an omni-directional
treadmill is mounted on the motion platform in order to improve VR immersion by
giving feedback to the human body. For this purpose we modify the well-known
octahedral manipulator in a way that it has one degree of kinematical
redundancy; namely an equiform reconfigurability of the base. The instantaneous
kinematics and singularities of this mechanism are studied, where especially
"unavoidable singularities" are characterized. These are poses of the motion
platform, which can only be realized by singular configurations of the
mechanism despite its kinematic redundancy.Comment: 13 pages, 6 figure
Production of \uptau τ lepton pairs with high p T jets at the LHC and the TauSpinner reweighting algorithm
The TauSpinner algorithm allows to modify the physics of the Monte Carlo
generated samples due to the changed assumptions of event production dynamics,
without re-generating events. To each event it attributes weights: the spin
effects of tau-lepton production or decay, or the production mechanism are
modified. There is no need to repeat the detector response simulation. We
document the extension to 2 to 4 processes in which the matrix elements for the
parton-parton scattering amplitudes into a tau-lepton pair and two outgoing
partons are used. Tree-level matrix elements for the Standard Model processes,
including the Higgs boson production are used. Automatically generated codes by
MadGraph5 have been adapted. Tests of the matrix elements, reweighting
algorithm and numerical results are presented. For averaged tau lepton
polarisation, we perform comparison of 2 to 2 and 2 to 4 matrix elements used
to calculate the spin weight in pp to tau tau j j events. We show, that for
events with tau-lepton pair close to the Z-boson peak, the tau-lepton
polarisation calculated using 2 to 4 matrix elements is very close to the one
calculated using 2 to 2 Born process only. For the m_(tautau) masses above the
Z-boson peak, the effect from including 2 to 4 matrix elements is also
marginal, however when restricting into subprocesses qq,q bar q to tau tau j j
only, it can lead to a 10% difference on the predicted tau-lepton polarisation.
Choice of electroweak scheme can have significant impact. The modification of
the electroweak or strong interaction can be performed with the re-weighting
technique. TauSpinner v.2.0.0, allows to introduce non-standard couplings for
the Higgs boson and study their effects in the vector-boson-fusion. The
discussion is relegated to forthcoming publications.Comment: 33 pages 7 figure
Simulating hard photon production with WHIZARD
One of the important goals of the proposed future collider
experiments is the search for dark matter particles using different
experimental approaches. The most general search approach is based on the
mono-photon signature, which is expected when production of the invisible final
state is accompanied by a hard photon from initial state radiation. Analysis of
the energy spectrum and angular distributions of those photons can shed light
on the nature of dark matter and its interactions. Therefore, it is crucial to
be able to simulate the signal and background samples in a uniform framework,
to avoid possible systematic biases. The WHIZARD program is a flexible tool,
which is widely used by collaborations for simulation of many
different "new physics" scenarios. We propose the procedure of merging the
matrix element calculations with the lepton ISR structure function implemented
in WHIZARD. It allows us to reliably simulate the mono-photon events, including
the two main Standard Model background processes: radiative neutrino pair
production and radiative Bhabha scattering. We demonstrate that cross sections
and kinematic distributions of mono-photon in neutrino pair-production events
agree with corresponding predictions of the KKMC, a Monte Carlo generator
providing perturbative predictions for SM and QED processes, which has been
widely used in the analysis of LEP data.Comment: 17 pages, 8 figures, 6 tables, 2 example steering file
Ultimate performance of polymer:fullerene bulk heterojunction tandem solar cells
We present the model calculations to explore the potential of polymer:fullerene tandem solar cells. As an approach we use a combined optical and electrical device model, where the absorption profiles are used as starting point for the numerical current-voltage calculations. With this model a maximum power efficiency of 11.7% for single cells has been achieved as a reference. For tandem structures with a ZnO/poly(3,4-ethylenedioxythiophene)/ poly(styrenesulphonic acid) middle electrode an ultimate efficiency of 14.1% has been calculated. In the optimum configuration the subcell with the narrowest band gap is placed closest to the incoming light. Consequently, tandem structures are expected to enhance the performance of optimized single cells by about 20%. © 2011 American Institute of Physics
Comparative study on usefulness of gentamycin-containing collagen implants in the treatment of patients with osteitis and osteomyelitis of the craniofacial skeleton
Introduction and objective
A reduction in incidences of peri-surgical complications due to infections is achieved by antibiotic prophylaxis The objective of the study was to assess the usefulness of gentamycin-containing collagen implants (GCCI) in the treatment of patients with osteitis and osteomyelitis of the craniofacial skeleton.
Material and Methods
The retrospective study included 103 patients with osteitis and osteomyelitis. 54 patients were treated intra-operatively with GCCI (Garamycin, EusaPharma, Europe). 49 patients were treated according to standard procedures. Light microscopy and in vitro culture techniques were applied for bacteria specific identification, and to investigate the resistance of detected microbiota to antibiotics. Patients received one dose of antibiotic pre-operatively. Post-operative antibiotic treatment was administered individually, according to clinical course and microbiological tests. The patients were followed-up on days 3, 7 and 14 after discharge for local complications; radiographic follow-up was performed 3, 6 and 12 months after surgery.
Results
The course of post-operative antibiotic therapy was shorter in GCCI patients than in the control group (median 1 vs. 7 days); they also required shorter hospitalization (median 3 vs. 4 days). Implantation of GCCI significantly reduced the incidence of local complications (OR 0.30, 95%CI 0.11–0.83, p<0.0001), independently of the use of postoperative antibiotic therapy. On follow-up after 3–12 months, all patients presented with good soft tissue and bone healing.
Conclusions
The results of this comparative study advocate the use of GCCI in osteomyelitis of various origin in oral and maxillofacial surgery, as they seemed to reduce the incidence of local complications, shorten antibiotic administration time and hospital stay
橘の花散る里のほととぎす--「万葉集」巻8,1472,1473番歌をめぐって
R-symmetry leads to a distinct low energy realisation of SUSY with a signicantly modified colour-charged sector featuring a Dirac gluino and scalar colour octets (sgluons). In the present work we recast results from LHC BSM searches to discuss the impact of R-symmetry on the squark and gluino mass limits. We work in the framework of the Minimal R-symmetric Supersymmetric Standard Model and take into account the NLO corrections to the squark production cross sections in the MRSSM that have become available recently. We find substantially weaker limits on squark masses compared to the MSSM: for simple scenarios with heavy gluinos and degenerate squarks, the MRSSM mass limit is > 1:7TeV, approximately 600 GeV lower than in the MSSM
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