2,768 research outputs found
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
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
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
Length-scale dependent deformation behavior of nanolayered Cu-based micropillars
By using microcompression methodology, deformation of nanolayered crystal/crystal (C/C) Cu/Zr and Cu/ Cr, and crystal/amorphous (C/A) Cu/CuZr micropillars was systematically investigated within wide ranges of intrinsic layer thickness (5 – 150 nm) and extrinsic sample diameter (300 – 1500 nm). The intrinsic size effect, extrinsic size effect and their interplay were respectively revealed. Competition between the intrinsic and extrinsic size effects leads to a common experimental observation of a critical layer thickness of about 20 nm, above which the deformation is predominantly intrinsic-size-related and insensitive to sample size, while below which the two size effects are comparable. The underlying deformation mechanisms are proposed to transform from bulk-like to small-volume materials behavior. Deformation mode is correspondingly transited from homogeneous extrusion/barreling to inhomogeneous shear banding, and the two competing modes coexist in the layer thickness range from about 50 to 20 nm. Besides these generalities, specific deformation features of the C/C and C/A micropillars are respectively discussed. In particular, deformation-induced devitrification in the amorphous layers promotes an extraordinary plasticity in the C/A micropillars, which provides a viable route to enhance the controllability of plastic deformation in metallic glassy composites. A deformation mode map is further developed to clearly elucidate the coupling intrinsic and extrinsic size effects on the deformation mode of nanolayered micropillars
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
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