179,863 research outputs found
A nonperturbative parametrization and scenario for EFT renormalization
We present a universal form of the -matrices renormalized in
nonperturbative regime and the ensuing notions and properties that fail
conventional wisdoms. A universal scale is identified and shown to be
renormalization group invariant. The effective range parameters are derived in
a nonperturbative scenario with some new predictions within the realm of
contact potentials. Some controversies are shown to be due to the failure of
conventional wisdoms.Comment: 5 pages, no figure, to appear in Europhys. Let
Effective range expansion in various scenarios of EFT(\notpi)
Using rigorous solutions, we compare the ERE parameters obtained in three
different scenarios of EFT(\notpi) in nonperturbative regime. A scenario with
unconventional power counting (like KSW) is shown to be disfavored by the PSA
data, while the one with elaborate prescription of renormalization but keeping
conventional power counting intact seems more promising.Comment: 6 pages, 3 tables, no figure, revtex4-1, minor revisions, to appear
in EP
Radiative and leptonic decays of the pseudoscalar charmonium state
The radiative and leptonic decays of and are studied. For decay, the second-order
electromagnetic tree-level diagram gives the leading contribution. The decay
rate of is calculated, the prediction is in good
agreement with the experimental data. For \eta_c\to l^+\l^-, both the tree
and loop diagrams are calculated. The analysis shows that the loop contribution
dominates, the contribution of tree diagram with intermediate state can
only modifies the decay rate by less than 1%. The prediction of the branching
ratios of and are very tiny within the standard
model. The smallness of these predictions within the standard model makes the
leptonic decays of sensitive to physics beyond the standard model.
Measurement of the leptonic decay may give information of new physics.Comment: 9 pages, 4 figures, RevTex, small change, version to appear in Phys.
Rev.
Antenna Miniaturization Based on Supperscattering Effect
Antennas are essential components of all existing radio equipments. The miniaturization of antenna is a key issue of antenna technology. Based on supperscattering effect, we found that when a small horn antenna is located inside of a dielectric core and covered with a complementary layer, its far field radiation pattern will be equivalent to a large horn antenna. The complementary layer with only axial parameters varying with radius is obtained using coordinate transformation theory. Besides, the influence of loss and perturbations of parameters on supperscattering effect is also investigated. Results show that the device is robust against the perturbation in the axial material parameters when the refractive index is kept invariant. Full-wave simulations based on finite element method are performed to validate the design
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