Update of the stranger story: the strange vector form factors of the nucleon

The strange vector form factors are investigated in the framework of the semi-bosonized SU(3) Nambu-Jona-Lasinio model (or chiral quark-soliton model). The mean-square strange radius \langle r^2 \rangle_s=-0.17\; \mbox{fm}^2 and the strange magnetic moment \mu_s = -0.45 are obtained in case of the constituent quark mass M=420 \;\mbox{MeV}. The results are compared with several different models

1/Nc1/N_c Rotational Corrections to gAg_A and Isovector Magnetic Moment of the Nucleon

The $1/N_c$ rotational corrections to the axial vector constant and the isovector magnetic moment of the nucleon are studied in the Nambu -- Jona-Lasinio model. We follow a semiclassical quantization procedure in terms of path integrals in which we can include perturbatively corrections in powers of angular velocity $\Omega \sim \frac 1{N_c}$. We find non-zero $1/N_c$ order corrections from both the valence and the Dirac sea quarks. These corrections are large enough to resolve the long-standing problem of a strong underestimation of both $g_A$ and $\mu^{IV}$ in the leading order. The axial constant $g_A$ is well reproduced, whereas the isovector magnetic moment $\mu^{IV}$ is still underestimated by 25 \%.Comment: (Revtex), 10 pages (3 figures available on request), report RUB-TPII-53/9

Strange and singlet form factors of the nucleon: Predictions for G0, A4, and HAPPEX-II experiments

We investigate the strange and flavor-singlet electric and magnetic form factors of the nucleon within the framework of the SU(3) chiral quark-soliton model. Isospin symmetry is assumed and the symmetry-conserving SU(3) quantization is employed, rotational and strange quark mass corrections being included. For the experiments G0, A4, and HAPPEX-II we predict the quantities $G^{0}_E + \beta G^{0}_M$ and $G^{\rm s}_E + \beta G^{\rm s}_M$. The dependence of the results on the parameters of the model and the treatment of the Yukawa asymptotic behavior of the soliton are investigated.Comment: 16 pages, 3 figures, Final version for publication in Eur. Phys. J.

ELISA: a cryocooled 10 GHz oscillator with 10-15 frequency stability

This article reports the design, the breadboarding and the validation of an ultra-stable Cryogenic Sapphire Oscillator operated in an autonomous cryocooler. The objective of this project was to demonstrate the feasibility of a frequency stability of 3x10-15 between 1 s and 1,000 s for the European Space Agency deep space stations. This represents the lowest fractional frequency instability ever achieved with cryocoolers. The preliminary results presented in this paper validate the design we adopted for the sapphire resonator, the cold source and the oscillator loop.Comment: 13 pages, 10 figure