5,309 research outputs found
Model independent analysis of top quark forward-backward asymmetry at the Tevatron up to \mathcal{O}(\as^2/\Lambda^2)
We present the complete calculations of the forward-backward asymmetry
() and the total cross section of top quark pair production induced
by dimension-six four quark operators at the Tevatron up to
\mathcal{O}(\as^2/\Lambda^2). Our results show that next-to-leading order
(NLO) QCD corrections can change and the total cross section by
about 10%. Moreover, NLO QCD corrections reduce the dependence of
and total cross section on the renormalization and factorization scales
significantly. We also evaluate the total cross section and the charge
asymmetry () induced by these operators at the Large Hadron Collider
(LHC) up to \mathcal{O}(\as^2/\Lambda^2), for the parameter space allowed by
the Tevatron data. We find that the value of induced by these
operators is much larger than SM prediction, and LHC has potential to discover
these NP effects when the measurement precision increases.Comment: 25 pages, 10 figures; final version in PR
Charge transfer between lead halide perovskite nanocrystals and single-walled carbon nanotubes
© 2020 The Royal Society of Chemistry. A charge transfer study between lead halide-based perovskite nanocrystals and single-walled carbon nanotubes (PNC@CNT nanocomposite) was performed. Solution-processed MAPbX3 PNCs displayed very bright luminescence, but it quenched in the presence of CNTs. This was attributed to the electron transfer from PNCs to CNTs. The detailed changes in fluorescence lifetime were investigated through time-correlated single-photon counting (TCSPC), which suggested mixed static and dynamic quenching along with a decrease in the lifetime. Morphological changes were investigated via transmission electron microscopy (TEM) and attributed to the incorporation of PNCs on long CNTs. Also, the PNC@CNT nanocomposite was explored for photoinduced current response, which indicated an ∼3 fold increase in photoconductivity under light illumination (with a 1 mV bias). This electron transfer study between PNCs and CNTs contributes to the exploration of charge dynamics
Chaotic scattering through coupled cavities
We study the chaotic scattering through an Aharonov-Bohm ring containing two
cavities. One of the cavities has well-separated resonant levels while the
other is chaotic, and is treated by random matrix theory. The conductance
through the ring is calculated analytically using the supersymmetry method and
the quantum fluctuation effects are numerically investigated in detail. We find
that the conductance is determined by the competition between the mean and
fluctuation parts. The dephasing effect acts on the fluctuation part only. The
Breit-Wigner resonant peak is changed to an antiresonance by increasing the
ratio of the level broadening to the mean level spacing of the random cavity,
and the asymmetric Fano form turns into a symmetric one. For the orthogonal and
symplectic ensembles, the period of the Aharonov-Bohm oscillations is half of
that for regular systems. The conductance distribution function becomes
independent of the ensembles at the resonant point, which can be understood by
the mode-locking mechanism. We also discuss the relation of our results to the
random walk problem.Comment: 13 pages, 9 figures; minor change
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