1,976 research outputs found
Spin Correlations in top quark pair production near threshold at the Linear Collider
We investigate the spin correlations in top quark pair production near
threshold at the linear collider. Comparing with the results above
the threshold region, we find that near the threshold region the off-diagonal
basis, the optimized decomposition of the top quark spins above the threshold
region, does not exist, and the beamline basis is the optimal basis, in which
there are the dominant spin components: the up-down (UD) component for scattering and the down-up (DU) component for scattering can
make up more than 50% of the total cross section, respectively.Comment: 12 pages, 3 figures, minor modification
Next-to-leading order QCD predictions for associated production of top squarks and charginos at the CERN LHC
We present the calculations of the complete next-to-leading order (NLO)
inclusive total cross sections for the associated production processes in the Minimal Supersymmetric Standard Model at
the CERN Large Hadron Collider. Our calculations show that the total cross
sections for the production for the lighter top
squark masses in the region 100 GeV 160 GeV can reach 1 pb
in the favorable parameter space allowed by the current precise experiments,
and in other cases the total cross sections generally vary from 10 fb to
several hundred fb except both 500 GeV and the
production channel. Moreover, we find that the
NLO QCD corrections in general enhance the leading order total cross sections
significantly, and vastly reduce the dependence of the total cross sections on
the renormalization/factorization scale, which leads to increased confidence in
predictions based on these results.Comment: 42 pages, 13 figures, RevTex4. Journal-ref adde
via SUSY FCNC couplings in the unconstrained MSSM
We recalculate the branching ratios for () induced by
SUSY FCNC couplings within the general unconstrained MSSM framework using mass
eigenstate approach. Our results show that the branching ratios for these
decays are larger than ones reported in previous literatures in the MSSM with
R-parity conservation, and they can reach , , and
, respectively, for favorable parameter values allowed by current
precise experiments. Thus, the branching ratios for and may be measurable at the LHC.Comment: 15 pages, 3 figures, minor changs in the Table
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Whole transcriptome sequencing identifies tumor-specific mutations in human oral squamous cell carcinoma
Background: The accumulation of somatic mutations in genes and molecular pathways is a major factor in the evolution of oral squamous cell carcinoma (OSCC), which sparks studies to identify somatic mutations with clinical potentials. Recently, massively parallel sequencing technique has started to revolutionize biomedical studies, due to the rapid increase in its throughput and drop in cost. Hence sequencing of whole transcriptome (RNA-Seq) becomes a superior approach in cancer studies, which enables the detection of somatic mutations and accurate measurement of gene expression simultaneously. Methods: We used RNA-Seq data from tumor and matched normal samples to investigate somatic mutation spectrum in OSCC. Results: By applying a sophisticated bioinformatic pipeline, we interrogated two tumor samples and their matched normal tissues and identified 70,472 tumor somatic mutations in protein-coding regions. We further identified 515 significantly mutated genes (SMGs) and 156 tumor-specific disruptive genes (TDGs), with six genes in both sets, including ANKRA2, GTF2H5, STOML1, NUP37, PPP1R26, and TAF1L. Pathway analysis suggested that SMGs were enriched in cell adhesion pathways, which are frequently indicated in tumor development. We also found that SMGs tend to be differentially expressed between tumors and normal tissues, implying a regulatory role of accumulation of genetic aberrations in these genes. Conclusions: Our finding of known tumor genes proves of the utility of RNA-Seq in mutation screening, and functional analysis of genes detected here would help understand the molecular mechanism of OSCC
Next-to-leading order QCD predictions for pair production of neutral Higgs bosons at the CERN Large Hadron Collider
We present the calculations of the complete NLO inclusive total cross
sections for pair production of neutral Higgs bosons through
annihilation in the minimal supersymmetric standard model at the CERN Large
Hadron Collider. In our calculations, we used both the DREG scheme and the DRED
scheme and found that the NLO total cross sections in the above two schemes are
the same. Our results show that the -annihilation contributions can
exceed ones of fusion and annihilation for ,
and productions when is large. In the case of , the
NLO corrections enhance the LO total cross sections significantly, which can
reach a few tens percent, while for , the corrections are relatively
small, and are negative in most parameter space. Moreover, the NLO QCD
corrections can reduce the dependence of the total cross sections on the
renormalization/factorization scale, especially for . We also use the
CTEQ6.1 PDF sets to estimate the uncertainty of LO and NLO total cross
sections, and find that the uncertainty arising from the choice of PDFs
increases with the increasing .Comment: 43 pages, 16 figures, minor changes, some references added, a version
to appear in PR
Next-to-Leading Order QCD Corrections to the Direct Top Quark Production via Model-independent FCNC Couplings at Hadron Colliders
We calculated the next-to-leading order (NLO) QCD corrections to the cross
sections for direct top quark productions induced by model--independent flavour
changing neutral current couplings at hadron colliders. The NLO results
increase the experimental sensitivity to the anomalous couplings. Our results
show that the NLO QCD corrections enhance the leading order (LO) total cross
sections at the Tevatron Run 2 about 60% for both of and
couplings, and enhance the LO total cross sections at the LHC
about 40% for couplings and 50% for couplings,
respectively. Moreover, the NLO QCD corrections vastly reduce the dependence of
the total cross sections on the renormalization or factorization scale, which
leads to increased confidence in predictions based on these results.Comment: 15 pages, 4 figures; published versio
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