11 research outputs found
城镇贫困人口的人力资源开发
我国城镇贫困人口数量近年来呈现日益增加的态势 ,引起了中央政府和社会各界的高度重视 ,并且已经采取了一些救济措施。为了从根本上解决城镇居民贫困问题 ,就要改变扶贫工作的观念和方法 ,变被动式扶贫为开发式扶贫 ,大力开发城镇贫困人口的人力资源。国家社会科学基金项目 (项目号 :02CJY002 )
Fermionic massive modes along cosmic strings
The influence on cosmic string dynamics of fermionic massive bound states
propagating in the vortex, and getting their mass only from coupling to the
string forming Higgs field, is studied. Such massive fermionic currents are
numerically found to exist for a wide range of model parameters and seen to
modify drastically the usual string dynamics coming from the zero mode currents
alone. In particular, by means of a quantization procedure, a new equation of
state describing cosmic strings with any kind of fermionic current, massive or
massless, is derived and found to involve, at least, one state parameter per
trapped fermion species. This equation of state exhibits transitions from
subsonic to supersonic regimes while the massive modes are filled.Comment: 27 pages, 15 figures, uses ReVTeX. Shortened version, accepted for
publication in Phys. Rev.
Equation of state of cosmic strings with fermionic current-carriers
The relevant characteristic features, including energy per unit length and
tension, of a cosmic string carrying massless fermionic currents in the
framework of the Witten model in the neutral limit are derived through
quantization of the spinor fields along the string. The construction of a Fock
space is performed by means of a separation between longitudinal modes and the
so-called transverse zero energy solutions of the Dirac equation in the vortex.
As a result, quantization leads to a set of naturally defined state parameters
which are the number densities of particles and anti-particles trapped in the
cosmic string. It is seen that the usual one-parameter formalism for describing
the macroscopic dynamics of current-carrying vortices is not sufficient in the
case of fermionic carriers.Comment: 30 pages, 15 figures, uses ReVTeX, equation of state corrected,
comments and references added. Accepted for publication in Phys. Rev.
Soft Photons in Hadron-Hadron Collisions: Synchrotron Radiation from the QCD Vacuum?
We discuss the production of soft photons in high energy hadron-hadron
collisions. We present a model where quarks and antiquarks in the hadrons emit
``synchrotron light'' when being deflected by the chromomagnetic fields of the
QCD vacuum, which we assume to have a nonperturbative structure. This gives a
source of prompt soft photons with frequencies in the c.m.
system of the collision in addition to hadronic bremsstrahlung. In comparing
the frequency spectrum and rate of ``synchrotron'' photons to experimental
results we find some supporting evidence for their existence. We make an
exclusive--inclusive connection argument to deduce from the ``synchrotron''
effect a behaviour of the neutron electric formfactor proportional
to for . We find this to be consistent with
available data. In our view, soft photon production in high energy
hadron-hadron and lepton-hadron collisions as well as the behaviour of
electromagnetic hadron formfactors for low are thus sensitive probes of
the nonperturbative structure of the QCD vacuum.Comment: Heidelberg preprint HD-THEP-94-36, 31 pages, LaTeX + ZJCITE.sty
(included), 12 figures appended as uuencoded compressed ps-fil
The Renormalization Group with Exact beta-Functions
The perturbative -function is known exactly in a number of
supersymmetric theories and in the 't Hooft renormalization scheme in the
model. It is shown how this allows one to compute the effective
action exactly for certain background field configurations and to relate bare
and renormalized couplings. The relationship between the MS and SUSY
subtraction schemes in super Yang-Mills theory is discussed
Flavor Production in Pb(160AGeV) on Pb Collisions: Effect of Color Ropes and Hadronic Rescattering
Collective interactions in the preequilibrium quark matter and hadronic
resonance gas stage of ultrarelativistic nucleus-nucleus collisions are studied
in the framework of the the transport theoretical approach RQMD. The paper
reviews string fusion into color ropes and hadronic rescattering which serve as
models for these interactions. Hadron production in central Pb(160AGeV) on Pb
collisions has been calculated. The changes of the final flavor composition are
more pronounced than in previous RQMD studies of light ion induced reactions at
200AGeV. The ratio of created quark pairs /(+) is
enhanced by a factor of 2.4 in comparison to results. Color rope formation
increases the initially produced antibaryons to 3 times the value in the `NN
mode', but only one quarter of the produced antibaryons survives because of
subsequent strong absorption. The differences in the final particle composition
for Pb on Pb collisions compared to S induced reactions are attributed to the
hadronic resonance gas stage which is baryon-richer and lasts longer.Comment: 60 pages + 11 postscript figures (uuencoded and included
Pair production of charged vector bosons in supercritical magnetic fields at finite temperatures
[[abstract]]The thermodynamic properties of an ideal gas of charged vector bosons (with mass m and charge e) is studied in a strong external homogeneous magnetic field no greater than the critical value Bcr=m2/e. The thermodynamic potential, after appropriate analytic continuation, is then used in the study of the spontaneous production of charged spin-one boson pairs from vacuum in the presence of a supercritical homogeneous magnetic field at finite temperature[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[countrycodes]]US
Domain wall network as QCD vacuum and the chromomagnetic trap formation under extreme conditions
The ensemble of Euclidean gluon field configurations represented by the
domain wall network is considered. A single domain wall is given by the
sine-Gordon kink for the angle between chromomagnetic and chromoelectric
components of the gauge field. The domain wall separates the regions with
self-dual and anti-self-dual fields. The network of the domain wall defects is
introduced as a combination of multiplicative and additive superpositions of
kinks. The character of the spectrum and eigenmodes of color-charged
fluctuations in the presence of the domain wall network is discussed. The
concept of the confinement-deconfinement transition in terms of the ensemble of
domain wall networks is outlined. Conditions for the formation of thick domain
wall junction during heavy ion collisions are discussed, and the spectrum of
color charged quasiparticles inside the trap is evaluated. An important
observation is the existence of the critical size of the trap stable
against gluon tachyonic modes, which means that deconfinement can occur only in
a finite region of space-time in principle. The size is related to the
value of gluon condensate .Comment: 20 pages, 10 figure