199,991 research outputs found
Partonic State and Single Transverse Spin Asymmetry in Drell-Yan Process
Single transverse-spin asymmetries have been studied intensively both in
experiment and theory. Theoretically, two factorization approaches have been
proposed. One is by using transverse-momentum-dependent factorization and the
asymmetry comes from the so called Sivers function. Another is by using
collinear factorization where the nonperturbative effect is parameterized by a
twist-3 hadronic matrix element. However, the factorized formulas for the
asymmetries in the two approaches are derived at hadron level formally by
diagram expansion, where one works with various parton density matrices of
hadrons. If the two factorizations hold, they should also hold at parton level.
We examine this for Drell-Yan processes by replacing hadrons with partons. By
calculating the asymmetry, Sivers function and the twist-3 matrix element at
nontrivial leading order of , we find that we can reproduce the
result of the transverse-momentum-dependent factorization. But we can only
verify the result of the collinear factorization partly. Two formally derived
relations between Sivers function and the twist-3 matrix element are also
examined with negative results.Comment: 15 pages, 6 figure
Quantum sensing of rotation velocity based on transverse field Ising model
We study a transverse-field Ising model (TFIM) in a rotational reference
frame. We find that the effective Hamiltonian of the TFIM of this system
depends on the system's rotation velocity. Since the rotation contributes an
additional transverse field, the dynamics of TFIM sensitively responses to the
rotation velocity at the critical point of quantum phase transition. This
observation means that the TFIM can be used for quantum sensing of rotation
velocity that can sensitively detect rotation velocity of the total system at
the critical point. It is found that the resolution of the quantum sensing
scheme we proposed is characterized by the half-width of Loschmidt echo of the
dynamics of TFIM when it couples to a quantum system S. And the resolution of
this quantum sensing scheme is proportional to the coupling strength \delta
between the quantum system S and the TFIM, and to the square root of the number
of spins N belonging the TFIM.Comment: 6 pages,6 figure
Numerical framework for transcritical real-fluid reacting flow simulations using the flamelet progress variable approach
An extension to the classical FPV model is developed for transcritical
real-fluid combustion simulations in the context of finite volume, fully
compressible, explicit solvers. A double-flux model is developed for
transcritical flows to eliminate the spurious pressure oscillations. A hybrid
scheme with entropy-stable flux correction is formulated to robustly represent
large density ratios. The thermodynamics for ideal-gas values is modeled by a
linearized specific heat ratio model. Parameters needed for the cubic EoS are
pre-tabulated for the evaluation of departure functions and a quadratic
expression is used to recover the attraction parameter. The novelty of the
proposed approach lies in the ability to account for pressure and temperature
variations from the baseline table. Cryogenic LOX/GH2 mixing and reacting cases
are performed to demonstrate the capability of the proposed approach in
multidimensional simulations. The proposed combustion model and numerical
schemes are directly applicable for LES simulations of real applications under
transcritical conditions.Comment: 55th AIAA Aerospace Sciences Meeting, Dallas, T
Precision era of the kinetic Sunyaev-Zeldovich effect: simulations, analytical models and observations and the power to constrain reionization
The kinetic SZ effect, which is the dominant CMB source at arc-minute scales
and Ghz, probes the ionized gas peculiar momentum up to the
epoch of reionization and is a sensitive measure of the reionization history.
We ran high resolution self-similar and CDM hydro simulations and
built an analytical model to study this effect. Our model reproduces the
CDM simulation results to several percent accuracy, passes various
tests against self-similar simulations, and shows a wider range of
applicability than previous analytical models. Our model in its continuous
version is free of simulation limitations such as finite simulation box and
finite resolution and allows an accurate prediction of the kinetic SZ power
spectrum . For the WMAP cosmology, we find for the reionization redshift and
. The corresponding temperature fluctuation is several K at
these ranges. The dependence of on the reionization history allows an
accurate measurement of the reionization epoch. For the Atacama cosmology
telescope experiment, can be measured with accuracy.
scales as . Given cosmological parameters,
ACT would be able to constrain with several percent accuracy.
Some multi-reionization scenarios degenerate in the primary CMB temperature and
TE measurement can be distinguished with confidence.Comment: 14 pages, 7 figures. Accepted by MNRAS. We corrected the primary CMB
power spectrum we used. We added discussions about the effects of lensing and
relativistic SZ correctio. We withdraw a claim about the patchy reionizatio
Numerical analysis of a downsized 2-stroke uniflow engine
In order to optimize the 2-stroke uniflow engine performance on vehicle applications, numerical analysis has been introduced, 3D CFD model has been built for the optimization of intake charge organization. The scavenging process was investigated and the intake port design details were improved. Then the output data from 3D CFD calculation were applied to a 1D engine model to process the analysis on engine performance. The boost system optimization of the engine has been carried out also. Furthermore, a vehicle model was also set up to investigate the engine in-vehicle performance
Shifting with
Precision measurements at the resonance agree well with the standard
model. However, there is still a hint of a discrepancy, not so much in by
itself (which has received a great deal of attention in the past several years)
but in the forward-backward asymmetry together with . The two
are of course correlated. We explore the possibilty that these and other
effects are due to the mixing of and with one or more heavy quarks.Comment: 11 pages, 1 Figure, LaTex fil
A Study of Gluon Propagator on Coarse Lattice
We study gluon propagator in Landau gauge with lattice QCD, where we use an
improved lattice action. The calculation of gluon propagator is performed on
lattices with the lattice spacing from 0.40 fm to 0.24 fm and with the lattice
volume from to . We try to fit our results by two
different ways, in the first one we interpret the calculated gluon propagators
as a function of the continuum momentum, while in the second we interpret the
propagators as a function of the lattice momentum. In the both we use models
which are the same in continuum limit. A qualitative agreement between two
fittings is found.Comment: Revtex 14pages, 11 figure
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