381 research outputs found
Exclusive Lambda_b -> Lambda l^+ l^- decay in two Higgs doublet model
Rare Lambda_b -> Lambda l^+ l^- decay is investigated in framework of general
two Higgs doublet model, in which a new source of CP violation exists (model
III). The polarization parameter, CP asymmetry and decay width are calculated.
It is shown that CP asymmetry is a very sensitive tool for establishing model
III.Comment: 16 pages, 3 figures, LaTeX formatte
Enhancing the top signal at Tevatron using Neural Nets
We show that Neural Nets can be useful for top analysis at Tevatron. The main
features of and background events on a mixed sample are projected in
a single output, which controls the efficiency and purity of the
signal.Comment: 11 pages, 6 figures (not included and available from the authors),
Latex, UB-ECM-PF 94/1
Texture of Yukawa coupling matrices in general two-Higgs-doublet model
We discuss possible parallel textures of the Yukawa coupling matrices in the
generaltwo-Higgs-doublet model (2HDM). In those textures the flavor changing
neutral currentsare naturally suppressed. Motivated by a phenomenologically
successful texturewith four texture zeros in the standard model, we propose a
predictive ansatz for the Yukawa coupling matrices with the same texture in the
general 2HDM. Compared with the six texture-zero based ansatz proposed by Cheng
and Sher, it is in a better agreement with the data of quark mixings and CP
violation. The four texture-zero based ansatz predicts a different hierarchy in
the Yukawa coupling matrix elements. As a consequence, in the lepton sector,
the related Yukawa couplings are less constrained by the experimental upper
bound of , which allows significantly larger predictions for
other processes. The contributions from neutral scalar interactions to the
lepton number violation decay modes are
calculated in both ansatz. It is shown that the predictions from the four
texture-zero based ansatz could be two order of magnitude greater than that
from the six texture-zero based one. The branching ratio of and
can reach and 1.3\tiems 10^{-10}
respectively. The predicted ratio of is also
larger and almost parameter independent. Those differences make the two ansatz
to be easily distinguished by the future experiments.Comment: 12 pages, 2 figure
Detection of the heavy Higgs boson at colliders
We consider the possibility of detecting a heavy Higgs boson () in
proposed colliders through the semi-leptonic mode . We show that
due to the non-monochromatic nature of the photon beams produced by the
laser-backscattering method, the resultant cross section for Higgs production
is much smaller than the on-resonance cross section and generally {\it
decreases} with increasing collider energy. Although continuum production
is expected to be negligible, we demonstrate the presence of and calculate
sizeable backgrounds from ,
with , respectively, and
.
This channel may be used to detect a Higgs of mass up to around 350~GeV
at a 0.5~TeV collider, assuming a nominal yearly luminosity of
10--20~fb.Comment: 18 pages (in RevTeX) plus Postscript figures (available by email or
FAX), NUHEP-TH-92-29 and DOE-309-CPP-47. (Revised version: NO CHANGES to the
manuscript, simply removed corrupted figure files
CP violation in the inclusive b -> s g decay in the framework of multi Higgs doublet models
We study the decay width and CP asymmetry of the inclusive process b--> s g
(g denotes gluon) in the multi Higgs doublet models with complex Yukawa
couplings, including next to leading QCD corrections. We analyse the
dependencies of the decay width and CP asymmetry on the scale \mu and CP
violating parameter \theta. We observe that there exist an enhancement in the
decay width and CP asymmetry is at the order of 10^{-2}.Comment: 11 pages, 8 Figure
Direct CP-asymmetry in Inclusive Rare B-decays in 2HDM
The direct CP-asymmetry in the inclusive and decays is investigated in the two-Higgs doublet extension of the
Standard Model (2HDM). The investigation is performed in the lowest
non-vanishing order of the perturbation theory using the existing restrictions
on the 2HDM parameters space. It is shown that the direct CP-asymmetry in the
decay can deviate significantly from the Standard Model
predictions. In the presence of only one source of CP-violation (the CKM matrix
weak phase) can have the sign opposite to that in
the SM. The new source of CP-violation can make
arbitrary small (unlike the SM case) and hence unmeasurable. Quantitatively,
the obtained results suffer from the uncertainty of the choice of
renormalization scale. As for the rate asymmetry, its
renormalization scale dependence in the lowest non-vanishing order does not
allow to conclude if this quantity is efficient for testing New Physics beyond
the Standard Model.Comment: 16 pages including 2 figure
High-throughput sequencing of Astrammina rara: Sampling the giant genome of a giant foraminiferan protist
<p>Abstract</p> <p>Background</p> <p>Foraminiferan protists, which are significant players in most marine ecosystems, are also genetic innovators, harboring unique modifications to proteins that make up the basic eukaryotic cell machinery. Despite their ecological and evolutionary importance, foraminiferan genomes are poorly understood due to the extreme sequence divergence of many genes and the difficulty of obtaining pure samples: exogenous DNA from ingested food or ecto/endo symbionts often vastly exceed the amount of "native" DNA, and foraminiferans cannot be cultured axenically. Few foraminiferal genes have been sequenced from genomic material, although partial sequences of coding regions have been determined by EST studies and mass spectroscopy. The lack of genomic data has impeded evolutionary and cell-biology studies and has also hindered our ability to test ecological hypotheses using genetic tools.</p> <p>Results</p> <p>454 sequence analysis was performed on a library derived from whole genome amplification of microdissected nuclei of the Antarctic foraminiferan <it>Astrammina rara</it>. Xenogenomic sequence, which was shown not to be of eukaryotic origin, represented only 12% of the sample. The first foraminiferal examples of important classes of genes, such as tRNA genes, are reported, and we present evidence that sequences of mitochondrial origin have been translocated to the nucleus. The recovery of a 3' UTR and downstream sequence from an actin gene suggests that foraminiferal mRNA processing may have some unusual features. Finally, the presence of a co-purified bacterial genome in the library also permitted the first calculation of the size of a foraminiferal genome by molecular methods, and statistical analysis of sequence from different genomic sources indicates that low-complexity tracts of the genome may be endoreplicated in some stages of the foraminiferal life cycle.</p> <p>Conclusions</p> <p>These data provide the first window into genomic organization and genetic control in these organisms, and also complement and expands upon information about foraminiferal genes based on EST projects. The genomic data obtained are informative for environmental and cell-biological studies, and will also be useful for efforts to understand relationships between foraminiferans and other protists.</p
The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity
We analyze the neutron electric dipole moment (EDM) in the Minimal
Supersymmetric Model with explicit R-parity violating terms. The leading
contribution to the EDM occurs at the 2-loop level and is dominated by the
chromoelectric dipole moments of quarks, assuming there is no tree-level
mixings between sleptons and Higgs bosons or between leptons and gauginos.
Based on the experimental constraint on the neutron EDM, we set limits on the
imaginary parts of complex couplings and
due to the virtual b-loop or tau-loop.Comment: final manuscript to appear in Phys. Rev. D, 15 pages, latex, 4
figures include
The CP asymmetry for B--> K^* l^+ l^- decay in the general two Higgs doublet model
We study CP asymmetry for the exclusive decay B --> K^* l^+ l^- in the two
Higgs doublet model with three level flavor changing neutral currents (model
III). We analyse the dependency of this quantity to the new phase coming from
the complex Yukawa couplings in the theory and we find that there exist a
considerable CP violation for the relevant process. Further, we see that the
sign of the Wilson coefficient C_7^{eff} can be determined by fixing dilepton
mass. Therefore, the future measurements of CP asymmetry for B --> K^* l^+ l^-
decay will give a powerful information about the sign of Wilson coefficient
C_{7}^{eff} and the new physics beyond the SM.Comment: 22 pages, 8 figure
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Technical review of entrained design report
Morgantown Energy Technology Center (METC) is planning to expand its in-house coal gasification R&D capabilities by installing a research facility that can address a number of concepts including entrained, fluid bed, and catalytic gasification and flash pyrolysis. This Advanced Gasification Concepts (AGC) facility design, as it currently stands, includes piping and instrumentation diagrams, vessel drawings and specifications, instrumentation lists and specifications, and equipment layout and isometric drawings. Before the design is finalized, a critique is needed to ensure that the intended flexibility and objectives can be met. The design approach was evaluated to determine whether the present design will meet the research objectives, including the need for flexibility. Heat and material balances, critical velocity requirements, vessel arrangements, potential operational problems, and instrumentation were reviewed. The mechanical design review included a critique of the drawings and specifications, adherence to standards and codes, materials of construction, vessels, piping, valves, heaters, and fittings. In addition, utilities requirements, heat transfer and particulate removal calculations, and pumping and heat exchanger requirements were checked. An evaluation of the equipment cost includes a critique of the reliability of the equipment cost breakdown, the areas of cost uncertainty, and the areas for potential cost savings. A safety analysis is also provided
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