1,140 research outputs found
New feature of low charm quark hadronization in collisions at TeV
Treating the light-flavor constituent quarks and antiquarks that can well
describe the data of light-flavor hadrons in collisions at
TeV as the underlying source of chromatically neutralizing the charm quarks of
low transverse momenta (), we show that the experimental data of
spectra of single-charm hadrons , ,
and at mid-rapidity in the low range
( GeV/) in collisions at TeV can
be well understood by the equal-velocity combination of perturbatively-created
charm quarks and those light-flavor constituent quarks and antiquarks. This
suggests a possible new scenario of low charm quark hadronization, in
contrast to the traditional fragmentation mechanism, in collisions at LHC
energies. This is also another support for the exhibition of the effective
constituent quark degrees of freedom for the small parton system created in
collisions at LHC energies.Comment: 7 pages, 5 figure
Production of single-charm hadrons by quark combination mechanism in -Pb collisions at TeV
If QGP-like medium is created in -Pb collisions at extremely high
collision energies, charm quarks that move in the medium can hadronize by
capturing the co-moving light quark(s) or anti-quark(s) to form the charm
hadrons. Using light quark spectra extracted from the experimental data
of light hadrons and a charm quark spectrum that is consistent with
perturbative QCD calculations, the central-rapidity data of spectra and
the spectrum ratios for mesons in the low range (
GeV) in minimum-bias -Pb collisions at TeV are well
described by quark combination mechanism in equal-velocity combination
approximation. The ratio in quark combination mechanism
exhibits the typical increase-peak-decrease behavior as the function of
, and the shape of the ratio for GeV is in agreement
with the preliminary data of ALICE collaboration in central rapidity region
and those of LHCb collaboration in forward rapidity region
. The global production of single-charm baryons is quantified using
the preliminary data and the possible enhancement (relative to light flavor
baryons) is discussed. The spectra of ,
in minimum-bias events and those of single-charm hadrons in high-multiplicity
event classes are predicted, which serves as the further test of the possible
change of the hadronization characteristic for low charm quarks in the
small system created in -Pb collisions at LHC energies.Comment: 13 pages, 8 figure
Phase Change Mechanisms During Femtosecond Laser Pulse Train Ablation of Nickel Thin Films
The mechanisms of nickel thin films irradiated by femtosecond laser pulse trains are studied by a model using molecular dynamics simulations and two-temperature model. It is found that the pulse train technology can change energy transport and corresponding phase change processes. Compared with single pulse ablation at the same total fluence, the pulse trains lead to (1) lower ablation rate with more and smaller uniform nanoparticles, (2) higher film surface temperatures and longer thermalization time, (3) much lower electron thermal conductivity that can further control heat-affected zone, (4) significantly smaller film compressive stresses and tensile stresses which reduce microcracks, and (5) a transition from phase explosion to the critical point phase separation which favors small uniform nanoparticle generation
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