6,649 research outputs found
Tuning thermal transport in nanotubes with topological defects
Using the atomistic nonequilibrium Green's function, we find that thermal
conductance of carbon nanotubes with presence of topological lattice imperfects
is remarkably reduced, due to the strong Rayleigh scattering of high-frequency
phonons. Phonon transmission across multiple defects behaves as a cascade
scattering based with the random phase approximation. We elucidate that phonon
scattering by structural defects is related to the spatial fluctuations of
local vibrational density of states (LVDOS). An effective method of tuning
thermal transport in low-dimensional systems through the modulation of LVDOS
has been proposed. Our findings provide insights into experimentally
controlling thermal transport in nanoscale devicesComment: 10 pages, 3 figure
Mode-coupling theory and molecular dynamics simulation for heat conduction in a chain with transverse motions
We study heat conduction in a one-dimensional chain of particles with
longitudinal as well as transverse motions. The particles are connected by
two-dimensional harmonic springs together with bending angle interactions. The
problem is analyzed by mode-coupling theory and compared with molecular
dynamics. We find very good, quantitative agreement for the damping of modes
between a full mode-coupling theory and molecular dynamics result, and a
simplified mode-coupling theory gives qualitative description of the damping.
The theories predict generically that thermal conductance diverges as N^{1/3}
as the size N increases for systems terminated with heat baths at the ends. The
N^{2/5} dependence is also observed in molecular dynamics which we attribute to
crossover effect.Comment: 17 pages, 13 figure
Updated predictions for graviton and photon associated production at the LHC
We present updated predictions on the inclusive total cross sections,
including the complete next-to-leading order QCD corrections, for the graviton
and photon associated production process in the large extra dimensions model at
the LHC with a center-of-mass energy of 7 and 8 TeV, using the parameters
according to the requirements of the ATLAS and CMS Collaborations. Moreover, we
also discuss in detail the dependence on the transverse momentum cut and
uncertainties due to the choices of scales and parton distribution functions.Comment: 5 pages, 3 figures, 2 tables, version published in PR
Quantum Phase Transition in Hall Conductivity on an Anisotropic Kagome Lattice
We study the quantum Hall effect(QHE) on the Kagom\'{e} lattice with
anisotropy in one of the hopping integrals. We find a new type of QHE
characterized by the quantization rules for Hall conductivity
and Landau Levels ( is an integer), which is different from any known type. This phase
evolves from the QHE phase with and in the isotropic case, which is realized in a system
with massless Dirac fermions (such as in graphene). The phase transition does
not occur simultaneously in all Hall plateaus as usual but in sequence from low
to high energies, with the increase of hopping anisotropy.Comment: 5 pages, 4 figure
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
Transverse momentum resummation in soft-collinear effective theory
We present a universal formalism for transverse momentum resummation in the
view of soft-collinear effective theory (SCET), and establish the relation
between our SCET formula and the well known Collins-Soper-Sterman's pQCD
formula at the next-to-leading logarithmic order (NLLO). We also briefly
discuss the reformulation of joint resummation in SCET.Comment: 23 pages, 7 figures; version to appear in Phys. Rev.
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