1,300 research outputs found
Clocking connector replaces adapter cables
Single cable using simplified, versatile clocking connector satisfies clocking variations that previously required many cables. Connector consists of specially fabricated grommet follower dial housing, dial assembly, and modified insert
Renormalization of One Meson Exchange Potentials and Their Currents
The Nucleon-Nucleon One Meson Exchange Potential, its wave functions and
related Meson Exchange Currents are analyzed for point-like nucleons. The
leading Nc contributions generate a local and energy independent potential
which presents 1/r^3 singularities, requiring renormalization. We show how
invoking suitable boundary conditions, neutron-proton phase shifts and deuteron
properties become largely insensitive to the nucleon substructure and to the
vector mesons. Actually, reasonable agreement with low energy data for
realistic values of the coupling constants (e.g. SU(3) values) is found. The
analysis along similar lines for the Meson Exchange Currents suggests that this
renormalization scheme implies tremendous simplifications while complying with
exact gauge invariance at any stage of the calculation.Comment: Talk given at 12th International Conference on Meson-Nucleon Physics
and the Structure of the Nucleon (MENU 2010), Williamsburg, Virginia, 31 May
- 4 Jun 201
Renormalization and Universality of Van der Waals forces
Renormalization ideas can profitably be exploited in conjunction with the
superposition principle of boundary conditions in the description of model
independent and universal scaling features of the singular and long range Van
der Waals force between neutral atoms. The dominance of the leading power law
is highlighted both in the scattering as well as in the bound state problem.
The role of off-shell two-body unitarity and causality within the Effective
Field Theory framework on the light of universality and scaling at low energies
is analyzed.Comment: 10 pages, 9 figures. Presented at 19th International IUPAP Conference
On Few-Body Problems In Physics (FB 19) 31 Aug - 5 Sep 2009, Bonn, German
Pion transition form factor in the Regge approach and incomplete vector-meson dominance
The concept of incomplete vector-meson dominance and Regge models is applied
to the transition form factor of the pion. First, we argue that variants of the
chiral quark model fulfilling the chiral anomaly may violate the Terazawa-West
unitarity bounds, as these bounds are based on unverified assumptions for the
real parts of the amplitudes, precluding a possible presence of polynomial
terms. A direct consequence is that the transition form factor need not
necessarily vanish at large values of the photon virtuality. Moreover, in the
range of the BaBar experiment, the Terazawa-West bound is an order of magnitude
above the data, thus is of formal rather than practical interest. Then we
demonstrate how the experimental data may be properly explained with incomplete
vector-meson dominance in a simple model with one state, as well as in more
sophisticated Regge models. Generalizations of the simple Regge model along the
lines of Dominguez result in a proper description of the data, where one may
adjust the parameters in such a way that the Terazawa-West bound is satisfied
or violated. We also impose the experimental constraint from the Z -> pi0 gamma
decay. Finally, we point out that the photon momentum asymmetry parameter may
noticeably influence the precision analysis.Comment: 11 pages, 7 figure
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