8,873 research outputs found
Understanding for flavor physics in the lepton sector
In this paper, we give a model for understanding flavor physics in the lepton
sector--mass hierarchy among different generations and neutrino mixing pattern.
The model is constructed in the framework of supersymmetry, with a family
symmetry . There are two right-handed neutrinos introduced for seesaw
mechanism, while some standard model(SM) gauge group singlet fields are
included which transforms non-trivially under family symmetry. In the model,
each order of contributions are suppressed by compared to the
previous one. In order to reproduce the mass hierarchy, and
, and are obtained
at leading-order(LO) and next-to-leading-order(NLO) respectively, while
electron can only get its mass through
next-to-next-to-next-to-leading-order(NNNLO) contributions. For neutrino mixing
angels, are
i.e. Bi-maximal mixing pattern as first approximation, while higher order
contributions can make them consistent with experimental results. As
corrections for and originate from the same
contribution, there is a relation predicted for them
. Besides, deviation from
for should have been as large as
deviation from 0 for if it were not the former is suppressed by a
factor 4 compared to the latter.Comment: version to appear in Phys. Rev.
Enhancing the robustness of dynamical decoupling sequences with correlated random phases
We show that the addition of correlated phases to the recently developed
method of randomized dynamical decoupling pulse sequences [Physical Review
Letters 122, 200403 (2019)] can improve its performance in quantum sensing. In
particular, by correlating the relative phases of basic pulse units in
dynamical decoupling sequences, we are able to improve the suppression of the
signal distortion due to pulse imperfections and spurious responses due
to finite-width pulses. This enhances selectivity of quantum sensors such
as those based on NV centers in diamond
Reliable energy level alignment at physisorbed molecule-metal interfaces from density functional theory.
A key quantity for molecule-metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal-molecule interfaces. The method builds on the "DFT+Σ" approach, grounded in many-body perturbation theory, which introduces an approximate electron self-energy that corrects the level alignment obtained from conventional DFT for missing exchange and correlation effects associated with the gas-phase molecule and substrate polarization. Here, we extend the DFT+Σ approach in two important ways: first, we employ optimally tuned range-separated hybrid functionals to compute the gas-phase term, rather than rely on GW or total energy differences as in prior work; second, we use a nonclassical DFT-determined image-charge plane of the metallic surface to compute the substrate polarization term, rather than the classical DFT-derived image plane used previously. We validate this new approach by a detailed comparison with experimental and theoretical reference data for several prototypical molecule-metal interfaces, where excellent agreement with experiment is achieved: benzene on graphite (0001), and 1,4-benzenediamine, Cu-phthalocyanine, and 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111). In particular, we show that the method correctly captures level alignment trends across chemical systems and that it retains its accuracy even for molecules for which conventional DFT suffers from severe self-interaction errors
- …