7,811 research outputs found
Collins effect in semi-inclusive deep inelastic scattering process with a He target
We re-examine our previous calculation on the Collins effect in
semi-inclusive deeply inelastic scattering (SIDIS) process with a He
target, and find that our previous treatment on the dilution factors may cause
the results larger than the realistic situation. We thus modify our calculation
in an improved treatment with an updated prediction on the
asymmetry for the JLab 12 GeV under the transverse
momentum dependent (TMD) factorization framework. Meanwhile, we also provide
the prediction of such asymmetry for the JLab 6 GeV and the prediction of the
asymmetry related to pretzelosity.Comment: 10 pages, 4 figures, figures 3 and 4 replaced as Erratu
The azimuthal asymmetry in single longitudinally polarized Drell-Yan process
We study the azimuthal asymmetry in the Drell-Yan
process, when the nucleon is longitudinally polarized. The asymmetry is
contributed by the combination of the Boer-Mulders function and the
longitudinal transversity distribution function. We consider the Drell-Yan
processes by beams colliding on the proton and deuteron targets,
respectively. We calculate the azimuthal asymmetries in these
processes using the Boer-Mulders function and the longitudinal transversity
from spectator models. We show that the study on single polarized
Drell-Yan processes can not only give the information on the new 3-dimensional
parton distribution functions in momentum space, but also shed light on the
chiral-odd structure of the longitudinally polarized nucleon.Comment: 7 pages, 3 figures. Final version for publication in PR
Perspective of Galactic dark matter subhalo detection on Fermi from the EGRET observation
The perspective of the detectability of Galactic dark matter subhaloes on the
Fermi satellite is investigated in this work. Under the assumptions that dark
matter annihilation accounts for the "GeV excess" of the Galactic diffuse
-rays discovered by EGRET and the -ray flux is dominated by the
contribution from subhaloes of dark matter, we calculate the expected number of
dark matter subhaloes that Fermi may detect. We show that Fermi may detect a
few tens to several hundred subhaloes in 1-year all sky survey. Since EGRET
observation is taken as a normalization, this prediction is independent of the
particle physics property of dark matter. The uncertainties of the prediction
are discussed in detail. We find that the major uncertainty comes from the mass
function of subhaloes, i.e., whether the subhaloes are "point like" (high-mass
rich) or "diffuse like" (low-mass rich). Other uncertainties like the
background estimation and the observational errors will contribute a factor of
.Comment: 16 pages, 4 figures and 1 table, accepted for publication in Chinese
Physics
Transonic Flows with Shocks Past Curved Wedges for the Full Euler Equations
We establish the existence, stability, and asymptotic behavior of transonic
flows with a transonic shock past a curved wedge for the steady full Euler
equations in an important physical regime, which form a nonlinear system of
mixed-composite hyperbolic-elliptic type. To achieve this, we first employ the
coordinate transformation of Euler-Lagrange type and then exploit one of the
new equations to identify a potential function in Lagrangian coordinates. By
capturing the conservation properties of the Euler system, we derive a single
second-order nonlinear elliptic equation for the potential function in the
subsonic region so that the transonic shock problem is reformulated as a
one-phase free boundary problem for a second-order nonlinear elliptic equation
with the shock-front as a free boundary. One of the advantages of this approach
is that, given the shock location or quivalently the entropy function along the
shock-front downstream, all the physical variables can expressed as functions
of the gradient of the potential function, and the downstream asymptotic
behavior of the potential function at the infinite exit can be uniquely
determined with uniform decay rate.
To solve the free boundary problem, we employ the hodograph transformation to
transfer the free boundary to a fixed boundary, while keeping the ellipticity
of the second-order equations, and then update the entropy function to prove
that it has a fixed point. Another advantage in our analysis here is in the
context of the real full Euler equations so that the solutions do not
necessarily obey Bernoulli's law with a uniform Bernoulli constant, that is,
the Bernoulli constant is allowed to change for different fluid trajectories.Comment: 35 pages, 2 figures in Discrete and Continuous Dynamical Systems, 36
(2016
Stability of Attached Transonic Shocks in Steady Potential Flow past Three-Dimensional Wedges
We develop a new approach and employ it to establish the global existence and
nonlinear structural stability of attached weak transonic shocks in steady
potential flow past three-dimensional wedges; in particular, the restriction
that the perturbation is away from the wedge edge in the previous results is
removed. One of the key ingredients is to identify a "good" direction of the
boundary operator of a boundary condition of the shock along the wedge edge,
based on the non-obliqueness of the boundary condition for the weak shock on
the edge. With the identification of this direction, an additional boundary
condition on the wedge edge can be assigned to make sure that the shock is
attached on the edge and linearly stable under small perturbation. Based on the
linear stability, we introduce an iteration scheme and prove that there exists
a unique fixed point of the iteration scheme, which leads to the global
existence and nonlinear structural stability of the attached weak transonic
shock. This approach is based on neither the hodograph transformation nor the
spectrum analysis, and should be useful for other problems with similar
difficulties.Comment: 28 Pages; 2 figure
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