44 research outputs found
Nonlinear evolution of the momentum dependent condensates in strong interaction: the ``pseudoscalar laser''
We discuss the relaxation of the scalar and pseudoscalar condensates after a
rapid quench from an initial state with fluctuations. If we include not only
the zero-mode but also higher modes of the condensates in the classical
evolution, we observe parametric amplification of those ``hard'' modes. Thus,
they couple nonlinearly to the ``soft'' modes. As a consequence, domains of
coherent pi-field emerge long after the initial spinodal decomposition. The
momentum-space distribution of pions emerging from the decay of that
momentum-dependent condensate is discussed.Comment: 6 Pages, REVTEX, 8 Figures; one reference and one figure adde
Nucleation versus Spinodal decomposition in a first order quark hadron phase transition
We investigate the scenario of homogeneous nucleation for a first order
quark-hadron phase transition in a rapidly expanding background of quark gluon
plasma. Using an improved preexponential factor for homogeneous nucleation
rate, we solve a set of coupled equations to study the hadronization and the
hydrodynamical evolution of the matter. It is found that significant
supercooling is possible before hadronization begins. This study also suggests
that spinodal decomposition competes with nucleation and may provide an
alternative mechanism for phase conversion particularly if the transition is
strong enough and the medium is nonviscous. For weak enough transition, the
phase conversion may still proceed via homogeneous nucleation.Comment: LaTeX, 10 pages with 7 Postscript figures, more discussions and
referencese added, typos correcte
Non-perturbative effects in a rapidly expanding quark-gluon plasma
Within first-order phase transitions, we investigate the pre-transitional
effects due to the nonperturbative, large-amplitude thermal fluctuations which
can promote phase mixing before the critical temperature is reached from above.
In contrast with the cosmological quark-hadron transition, we find that the
rapid cooling typical of the RHIC and LHC experiments and the fact that the
quark-gluon plasma is chemically unsaturated suppress the role of
non-perturbative effects at current collider energies. Significant supercooling
is possible in a (nearly) homogeneous state of quark gluon plasma.Comment: LaTeX, 7 pages with 7 Postscript figures. Figures added, discussions
added. Version to appear in Phys. Rev.
Bioinspired artificial photonic nanoarchitecture using the elytron of the beetle Trigonophorus rothschildi varians as a 'blueprint'
An unusual, intercalated photonic nanoarchitecture was discovered in the elytra of Taiwanese Trigonophorus rothschildi varians beetles. It consists of a multilayer structure intercalated with a random distribution of cylindrical holes normal to the plane of the multilayer. The nanoarchitectures were characterized structurally by scanning electron microscopy and optically by normal incidence, integrated and goniometric reflectance measurements. They exhibit an unsaturated specular and saturated non-specular component of the reflected light. Bioinspired, artificial nanoarchitectures of similar structure and with similar properties were realized by drilling holes of submicron size in a multilayer structure, showing that such photonic nanoarchitectures of biological origin may constitute valuable blueprints for artificial photonic materials
DCC dynamics with the SU(3) linear sigma model
The SU(3) extension of the linear sigma model is employed to elucidate the
effect of including strangeness on the formation of disoriented chiral
condensates. By means of a Hartree factorization, approximate dispersion
relations for the 18 scalar and pseudoscalar meson species are derived and
their self-consistent solution makes it possible to trace out the thermal path
of the two order parameters as well as delineate the region of instability
within which spontaneous pair creation becomes possible. The results depend
significantly on the employed sigma mass, with the highest values yielding the
largest regions of instability. An approximate solution of the equations of
motion for the order parameter in scenarios emulating uniform scaling
expansions show that even with a rapid quench only the pionic modes grow
unstable. Nevertheless, the rapid and oscillatory relaxation of the order
parameters leads to enhanced production of both pions and (to a lesser degree)
kaons.Comment: 29 pages, RevTeX, 11 postscript figures, discussion about anomaly
term adde
TLM-converter: Reorganization of long time-lapse microscopy datasets for downstream image analysis
10.2144/000113704BioTechniques51149-54BTNQ
Regularly curved carbon nanotubes
The increasing number of reports on regularly curved carbon nanotube‐type architectures makes it increasingly important to understand the structure of these nano‐objects, to predict their properties, and to get insight in the way they form. The present work attempts to explore some properties of regularly curved carbon nanotube by combining structural modeling, mechanical calculations, and experimental high‐resolution transmission electron microscopy (HRTEM) data
Photon assisted implantation -PAI-
The junction depth reduction for B implanted under PA conditions in Si was investigated.It was found that low energy implantation and short annealing times promote higher values of junction depth reduction.Under PA conditions, an altered defect structure is produced which influences the diffusion of dopants.The combination of the modified defect distribution with low dose rate implantation may reduce the number of scattering centers for charge carriers, which affects sheet resistance