5,100 research outputs found
Reduction of the QCD string to a time component vector potential
We demonstrate the equivalence of the relativistic flux tube model of mesons
to a simple potential model in the regime of large radial excitation. We make
no restriction on the quark masses; either quark may have a zero or finite
mass. Our primary result shows that for fixed angular momentum and large radial
excitation, the flux tube/QCD string meson with a short-range Coulomb
interaction is described by a spinless Salpeter equation with a time component
vector potential V(r) = ar - k/r.Comment: RevTeX4, 10 pages, 3 eps figure
The majority of human CD3 epitopes are conferred by the epsilon chain
Transgenic mouse T cells expressing the human CD3ε chain bind the majority (29/36) of monoclonal antibodies (mAbs) specific for human CD3. A proportion of these mAbs are also able to recognize isolated CD3ε in a soluble, recombinant form. Thus, CD3ε can confer most CD3 epitopes on the TCR-CD3 complex, but many determinants may require assembly of the complex for their formation. A number ot mAbs did not recognize ε-transgenic T cells and probably need other CD3 subunits for binding. CD3-specific mAbs from each of the three groups defined here, as well as mAbs directed against the TCRαβ heterodimer, are all able to activate T cells. Therefore mAb attachment at several different sites on the TCR-CD3 complex can give rise to activation signals. This suggests that the cross-linking function of mitogenic antibodies may be their most significant property, rather than the perturbation of a particular ‘functional epitope
Universal light quark mass dependence and heavy-light meson spectroscopy
Clean predictions are presented for all the spin-averaged heavy-light meson
spectroscopies. A new symmetry is identified wherein the energy eigenstates
have a universal dependence on both the light and heavy quark masses. This
universality is used in an efficient analysis of these mesons within the QCD
string/flux tube picture. Unique predictions for all the D, D_s, B, and B_s
type mesons in terms of just four measured quantities.Comment: REVTeX4, 6 pages, 9 eps figure
Size effect on properties of varistors made from zinc oxide nanoparticles through low temperature spark plasma sintering
Conditions for the elaboration of nanostructured varistors by spark plasma sintering (SPS) are investigated, using 8-nm zinc oxide nanoparticles synthesized following an organometallic approach. A binary system constituted of zinc oxide and bismuth oxide nanoparticles is used for this purpose. It is synthesized at roomtemperature in an organic solution through the hydrolysis of dicyclohexylzinc and bismuth acetate precursors. Sintering of this material is performed by SPS at various temperatures and dwell times. The determination of the microstructure and the chemical composition of the as-prepared ceramics are based on scanning electron microscopy and X-ray diffraction analysis. The nonlinear electrical characteristics are evidenced by current–voltage measurements. The breakdown voltage of these nanostructured varistors strongly depends on grain sizes. The results show that nanostructured varistors are obtained by SPS at sintering temperatures ranging from 550 to 600 8C
Universality of Regge and vibrational trajectories in a semiclassical model
The orbital and radial excitations of light-light mesons are studied in the
framework of the dominantly orbital state description. The equation of motion
is characterized by a relativistic kinematics supplemented by the usual funnel
potential with a mixed scalar and vector confinement. The influence of finite
quark masses and potential parameters on Regge and vibrational trajectories is
discussed. The case of heavy-light mesons is also presented.Comment: 12 page
Digestion of sludge at 35, 55 och 60 °C :Evaluation of hygienization, biogas production and reduction of pharmaceuticals and PAH
Dynamics of the QCD String with Light and Heavy Quarks
The generalization of the effective action [1] of the quark--antiquark system
in the confining vacuum is performed for the case of arbitrary quark masses.
The interaction of quarks is described by the averaged Wilson loop for which we
use the minimal area law asymptotics.
The system is quantized by the path integral method and the quantum
Hamiltonian is obtained. It contains not only quark degrees of freedom but also
the string energy density.
As well as in the equal masses case [1] two dynamical regimes are found [2]:
for large orbital excitations () the system is represented as rotating
string, which leads to asymptotically linear Regge trajectories, while at small
one obtains a potential-like relativistic or nonrelativistic regime.
In the limiting cases of light-light and heavy-light mesons a unified
description is developed [2]. For the Regge trajectories one obtains nearly
straight-line patterns with the slope very close to and correspondingly. The upper bound on the light quark(s) masses which
doesn't change considerably this property of the trajectories is also found.Comment: 31 pages, preprint ITEP 62-9
Nonperturbative QCD Vacuum Effects in Nonlocal Quark Dynamics
A straightforward calculation reveals the essentially nonlocal character of
the leading heavy interaction arising from nonperturbative gluon
field correlations in the model of a fluctuating QCD vacuum. In light of this
quarkonium spin splitting ratio predictions which have supported the scalar
confinement ansatz are reconsidered as a specific example of possible
consequences for spectroscopy.Comment: Latex, 9 page
Odderon and Pomeron from the Vacuum Correlator Method
Glueball masses with J<=7 are computed both for C=+1 and C=-1 using the
string Hamiltonian derived in the framework of the Vacuum Correlator Method. No
fitting parameters are used, and masses are expressed in terms of string
tension and effective value of . We extend the calculations
done for J<=3 using the same Hamiltonian, which provided glueball masses in
good agreement with existing lattice data, to higher mass states. It is shown
that 3^{--}, 5^{--} and 7^{--} states lie on the odderon trajectories with the
intercept around or below 0.14. Another odderon trajectory with 3g glueballs of
Y-shape, corresponds to 11% higher masses and low intercept. These findings are
in agreement with recent experimental data, setting limits on the odderon
contribution to the exclusive reactions.Comment: 16 pages. Journal version. To be published in Phys.Lett.
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