25,536 research outputs found
Data Unfolding with Wiener-SVD Method
Data unfolding is a common analysis technique used in HEP data analysis.
Inspired by the deconvolution technique in the digital signal processing, a new
unfolding technique based on the SVD technique and the well-known Wiener filter
is introduced. The Wiener-SVD unfolding approach achieves the unfolding by
maximizing the signal to noise ratios in the effective frequency domain given
expectations of signal and noise and is free from regularization parameter.
Through a couple examples, the pros and cons of the Wiener-SVD approach as well
as the nature of the unfolded results are discussed.Comment: 26 pages, 12 figures, match the accepted version by JINS
Galilean invariance of lattice Boltzmann models
It is well-known that the original lattice Boltzmann (LB) equation deviates
from the Navier-Stokes equations due to an unphysical velocity dependent
viscosity. This unphysical dependency violates the Galilean invariance and
limits the validation domain of the LB method to near incompressible flows. As
previously shown, recovery of correct transport phenomena in kinetic equations
depends on the higher hydrodynamic moments. In this Letter, we give specific
criteria for recovery of various transport coefficients. The Galilean
invariance of a general class of LB models is demonstrated via numerical
experiments
Generalized Haldane Equation and Fluctuation Theorem in the Steady State Cycle Kinetics of Single Enzymes
Enyzme kinetics are cyclic. We study a Markov renewal process model of
single-enzyme turnover in nonequilibrium steady-state (NESS) with sustained
concentrations for substrates and products. We show that the forward and
backward cycle times have idential non-exponential distributions:
\QQ_+(t)=\QQ_-(t). This equation generalizes the Haldane relation in
reversible enzyme kinetics. In terms of the probabilities for the forward
() and backward () cycles, is shown to be the
chemical driving force of the NESS, . More interestingly, the moment
generating function of the stochastic number of substrate cycle ,
follows the fluctuation theorem in the form of
Kurchan-Lebowitz-Spohn-type symmetry. When $\lambda$ = $\Delta\mu/k_BT$, we
obtain the Jarzynski-Hatano-Sasa-type equality:
1 for all , where is the fluctuating chemical work
done for sustaining the NESS. This theory suggests possible methods to
experimentally determine the nonequilibrium driving force {\it in situ} from
turnover data via single-molecule enzymology.Comment: 4 pages, 3 figure
Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors
The superconducting gap is the fundamental parameter that characterizes the
superconducting state, and its symmetry is a direct consequence of the
mechanism responsible for Cooper pairing. Here we discuss about angle-resolved
photoemission spectroscopy measurements of the superconducting gap in the
Fe-based high-temperature superconductors. We show that the superconducting gap
is Fermi surface dependent and nodeless with small anisotropy, or more
precisely, a function of momentum. We show that while this observation is
inconsistent with weak coupling approaches for superconductivity in these
materials, it is well supported by strong coupling models and global
superconducting gaps. We also suggest that the strong anisotropies measured by
other probes sensitive to the residual density of states are not related to the
pairing interaction itself, but rather emerge naturally from the smaller
lifetime of the superconducting Cooper pairs that is a direct consequence of
the momentum dependent interband scattering inherent to these materials.Comment: 7 pages, 5 figure
Exotic mesons from quantum chromodynamics with improved gluon and quark actions on the anisotropic lattice
Hybrid (exotic) mesons, which are important predictions of quantum
chromodynamics (QCD), are states of quarks and anti-quarks bound by excited
gluons. First principle lattice study of such states would help us understand
the role of ``dynamical'' color in low energy QCD and provide valuable
information for experimental search for these new particles. In this paper, we
apply both improved gluon and quark actions to the hybrid mesons, which might
be much more efficient than the previous works in reducing lattice spacing
error and finite volume effect. Quenched simulations were done at
and on a anisotropic lattice using our PC cluster. We
obtain MeV for the mass of the hybrid meson
in the light quark sector, and Mev in the
charm quark sector; the mass splitting between the hybrid meson in the charm quark sector and the spin averaged S-wave charmonium mass
is estimated to be MeV. As a byproduct, we obtain MeV for the mass of a P-wave or
meson and MeV for the mass of a P-wave meson, which are comparable to their experimental value 1426 MeV for the
meson. The first error is statistical, and the second one is
systematical. The mixing of the hybrid meson with a four quark state is also
discussed.Comment: 12 pages, 3 figures. Published versio
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