8,299 research outputs found
Resonant production of the fourth family slepton at the LHC
The resonant production of the fourth family slepton ~l_4 via R-parity
violating interactions of supersymmetry at the Large Hadron Collider has been
investigated. We study the decay mode of ~l_4 into the fourth family neutrino
nu_4 and W boson. The signal will be a like-sign dimuon and dijet if the fourth
family neutrino has Majorana nature. We discuss the constraints on the R-parity
violating couplings lambda and lambda' of the fourth family charged slepton at
the LHC with the center of mass energies of 7, 10 and 14 TeV.Comment: 8 pages, 4 figures, 4 table
Emitter Location Finding using Particle Swarm Optimization
Using several spatially separated receivers, nowadays positioning techniques, which are implemented to determine the location of the transmitter, are often required for several important disciplines such as military, security, medical, and commercial applications. In this study, localization is carried out by particle swarm optimization using time difference of arrival. In order to increase the positioning accuracy, time difference of arrival averaging based two new methods are proposed. Results are compared with classical algorithms and Cramer-Rao lower bound which is the theoretical limit of the estimation error
Anomalous resonant production of the fourth family up type quarks at the LHC
Considering the present limits on the masses of fourth family quarks from the
Tevatron experiments, the fourth family quarks are expected to have mass larger
than the top quark. Due to their expected large mass they could have different
dynamics than the quarks of three families of the Standard Model. The resonant
production of the fourth family up type quark t' has been studied via anomalous
production subprocess gq_i-->t' (where q_i=u,c) at the LHC with the center of
mass energy 10 TeV and 14 TeV. The signatures of such process are discussed
within the SM decay modes. The sensitivity to anomalous coupling
\kappa/\Lambda=0.1 TeV^(-1) can be reached at \sqrt{s}=10 TeV and L_int=100
pb^(-1).Comment: 14 pages, 13 figures, 7 table
Probing Charged Higgs Boson Couplings at the FCC-hh Collider
Many of the new physics models predicts a light Higgs boson similar to the
Higgs boson of the Standard Model (SM) and also extra scalar bosons. Beyond the
search channels for a SM Higgs boson, the future collider experiments will
explore additional channels that are specific to extended Higgs sectors. We
study the charged Higgs boson production within the framework of two Higgs
doublet models (THDM) in the proton-proton collisions at the FCC-hh collider.
With an integrated luminosity of 500 fb at very high energy frontier, we
obtain a significant coverage of the parameter space and distinguish the
charged Higgs-top-bottom interaction within the THDM or other new physics
models with charged Higgs boson mass up to 1 TeV.Comment: 22 pages, 26 figures, 6 table
Top quark FCNC couplings at future circular hadron electron colliders
A study of single top quark production via flavor changing neutral current
interactions at vertices is performed at future circular hadron
electron collider. The signal cross sections for the processes and in the collision of electron
beam with energy 60 GeV and proton beam with energy 50 TeV are
calculated. In the analysis, the invariant mass distributions of three jets
reconstructing top quark mass, requiring one b-tagged jet and other two jets
reconstructing the mass are used to count signal and background events
after all selection cuts. The upper limits on the anomalous flavor changing
neutral current couplings are found to be 0.01 at
future circular hadron electron collider for fb with the
fast simulation of detector effects. Signal significance depending on the
couplings is analyzed and an enhanced sensitivity is found to the
branching ratio BR() at the future circular hadron electron
collider when compared to the current experimental results.Comment: 11 pages, 4 Figures, 4 Tables, to appear in Phys. Rev.
Transgene silencing and transgene-derived siRNA production in tobacco plants homozygous for an introduced AtMYB90 construct
Transgenic tobacco (Nicotiana tabacum) lines were engineered to ectopically over-express AtMYB90 (PAP2), an R2-R3 Myb gene associated with regulation of anthocyanin production in Arabidopsis thaliana. Independently transformed transgenic lines, Myb27 and Myb237, accumulated large quantities of anthocyanin, generating a dark purple phenotype in nearly all tissues. After self-fertilization, some progeny of the Myb27 line displayed an unexpected pigmentation pattern, with most leaves displaying large sectors of dramatically reduced anthocyanin production. The green-sectored 27Hmo plants were all found to be homozygous for the transgene and, despite a doubled transgene dosage, to have reduced levels of AtMYB90 mRNA. The observed reduction in anthocyanin pigmentation and AtMYB90 mRNA was phenotypically identical to the patterns seen in leaves systemically silenced for the AtMYB90 transgene, and was associated with the presence of AtMYB90-derived siRNA homologous to both strands of a portion of the AtMYB90 transcribed region. Activation of transgene silencing in the Myb27 line was triggered when the 35S::AtMYB90 transgene dosage was doubled, in both Myb27 homozygotes, and in plants containing one copy of each of the independently segregating Myb27 and Myb237 transgene loci. Mapping of sequenced siRNA molecules to the Myb27 TDNA (including flanking tobacco sequences) indicated that the 3' half of the AtMYB90 transcript is the primary target for siRNA associated silencing in both homozygous Myb27 plants and in systemically silenced tissues. The transgene within the Myb27 line was found to consist of a single, fully intact, copy of the AtMYB90 construct. Silencing appears to initiate in response to elevated levels of transgene mRNA (or an aberrant product thereof) present within a subset of leaf cells, followed by spread of the resulting small RNA to adjacent leaf tissues and subsequent amplification of siRNA production.Funding for this research is provided by the United States Department of Agriculture
Measurements of Metastable Staus at Linear Colliders
We consider scenarios in which the lightest sparticle (LSP) is the gravitino and the next-to-lightest sparticle (NLSP) is a metastable stau. We examine the production of stau pairs in e^{+}e^{-} annihilation at ILC and CLIC energies. In addition to three minimal supergravity (mSUGRA) benchmark scenarios proposed previously, we consider a new high-mass scenario in which effects catalyzed by stau bound states yield abundances of {6,7}Li that fit the astrophysical data better than standard Big-Bang nucleosynthesis. This scenario could be probed only at CLIC energies. In each scenario, we show how the stau mixing angle may be determined from measurements of the total stau pair-production cross sections with polarized beams, and of the tau polarization in stau decays. Using realistic ILC and CLIC luminosity spectra, we find for each scenario the centre-of-mass energy that maximizes the number of staus with \beta \gamma < 0.4, that may be trapped in a generic detector. The dominant sources of such slow-moving staus are generically the pair production and cascade decays of heavier sparticles with higher thresholds, and the optimal centre-of-mass energy is typically considerably beyond 2 m_{\tilde\tau_1}
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