5,502 research outputs found
Inclusive production at factories
Within the nonrelativistic QCD (NRQCD) factorization framework, we
investigate the inclusive production of the meson associated with either
light hadrons or charmed hadrons at factory energy GeV.
Both the leading color-singlet and color-octet channels are included. For the
production associated with light hadrons, the total production rate is
dominated by the color-octet channel, thus the future measurement of this
process may impose useful constraint on the value of the color-octet matrix
element ; for the production associated with
charmed hadrons, the total production rate is about one order of magnitude
smaller, and dominated by the color-singlet channel.Comment: v2, 23 pages, 1 table, 6 figures. Minor corrections, and a note
added, accepted for publication in PR
Dynamics and correlation length scales of a glass-forming liquid in quiescent and sheared conditions
We numerically study dynamics and correlation length scales of a colloidal
liquid in both quiescent and sheared conditions to further understand the
origin of slow dynamics and dynamic heterogeneity in glass-forming systems. The
simulation is performed in a weakly frustrated two-dimensional liquid, where
locally preferred order is allowed to develop with increasing density. The
four-point density correlations and bond-orientation correlations, which have
been frequently used to capture dynamic and static length scales in a
quiescent condition, can be readily extended to a system under steady shear in
this case. In the absence of shear, we confirmed the previous findings that the
dynamic slowing down accompanies the development of dynamic heterogeneity. The
dynamic and static length scales increase with -relaxation time
as power-law with . In the
presence of shear, both viscosity and have power-law dependence
on shear rate in the marked shear thinning regime. However, dependence of
correlation lengths cannot be described by power laws in the same regime.
Furthermore, the relation between length scales
and dynamics holds for not too strong shear where thermal fluctuations and
external forces are both important in determining the properties of dense
liquids. Thus, our results demonstrate a link between slow dynamics and
structure in glass-forming liquids even under nonequilibrium conditions.Comment: 9 pages, 17 figures. Accepted by J. Phys.: Condens. Matte
Structure, compressibility factor and dynamics of highly size-asymmetric binary hard-disk liquids
By using event-driven molecular dynamics simulation, we investigate effects
of varying the area fraction of the smaller component on structure,
compressibility factor and dynamics of the highly size-asymmetric binary
hard-disk liquids. We find that the static pair correlations of the large disks
are only weakly perturbed by adding small disks. The higher-order static
correlations of the large disks, by contrast, can be strongly affected. The
compressibility factor of the system first decreases and then increases upon
increasing the area fraction of the small disks and separating different
contributions to it allows to rationalize this non-monotonic phenomenon.
Furthermore, adding small disks can influence dynamics of the system in
quantitative and qualitative ways. For the large disks, the structural
relaxation time increases monotonically with increasing the area fraction of
the small disks at low and moderate area fractions of the large disks. In
particular, "reentrant" behavior appears at sufficiently high area fractions of
the large disks, strongly resembling the reentrant glass transition in
short-ranged attractive colloids and the inverted glass transition in binary
hard spheres with large size disparity. By tuning the area fraction of the
small disks, relaxation process for the small disks shows concave-to-convex
crossover and logarithmic decay behavior, as found in other binary mixtures
with large size disparity. Moreover, diffusion of both species is suppressed by
adding small disks. Long-time diffusion for the small disks shows
power-law-like behavior at sufficiently high area fractions of the small disks,
which implies precursors of a glass transition for the large disks and a
localization transition for the small disks. Therefore, our results demonstrate
the generic dynamic features in highly size-asymmetric binary mixtures.Comment: 9 pages, 12 figure
Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions
Based on the coalescence model for light nuclei production, we show that the
yield ratio of
, d, and H in heavy-ion collisions is sensitive to the neutron relative
density fluctuation
at kinetic freeze-out. From recent experimental data in central Pb+Pb
collisions at ~GeV, ~GeV, ~GeV, ~GeV and
~GeV measured by the NA49 Collaboration at the CERN Super Proton
Synchrotron (SPS), we find a possible non-monotonic behavior of as a
function of the collision energy with a peak at ~GeV,
indicating that the density fluctuations become the largest in collisions at
this energy. With the known chemical freeze-out conditions determined from the
statistical model fit to experimental data, we obtain a chemical freeze-out
temperature of MeV and baryon chemical potential of MeV
at this collision energy, which are close to the critical endpoint in the QCD
phase diagram predicted by various theoretical studies. Our results thus
suggest the potential usefulness of the yield ratio of light nuclei in
relativistic heavy-ion collisions as a direct probe of the large density
fluctuations associated with the QCD critical phenomena.Comment: 6 pages, 1 figure, 2 tables. Correlations between neutron and proton
density fluctuations considered and presentation improved. Accepted version
to appear in PL
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