Biomedical subjects

R Schiavilla

Publications and source records attributed to R Schiavilla.

At least 19 recordsLinked to original sources

PubMed2005

Polarization transfer in 4He(e-->,e'p-->)3H: is the ratio G E p/G M p ) modified in the nuclear medium?

Polarization observables in the (4)He(e-->,e'p-->)(3)H reaction are calculated using accurate three- and four-nucleon bound-state wave functions, a realistic model for the nuclear electromagnetic current operator, and a treatment of final-state interactions with an optical potential. In contrast to earlier studies, no significant discrepancies are found between theory and experiment both for the ratio of transverse to longitudinal polarization transfers and for the induced polarization, when free-nucleon electromagnetic form factors are used in the current operator. The present results challenge the current interpretation of the experimental data in terms of medium-modified form factors.

Journal Article↗

PubMed2004

Parity-violating electron deuteron scattering and the proton's neutral weak axial vector form factor.

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2=0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.

Journal Article↗

PubMed2000

Realistic calculation of the 3He + p (hep) astrophysical factor.

The astrophysical factor for the proton weak capture on 3He is calculated with correlated hyperspherical harmonic wave functions corresponding to a realistic Hamiltonian consisting of the Argonne v(18) two-nucleon and Urbana-IX three-nucleon interactions. The nuclear weak current has vector and axial-vector components with one- and many-body terms. All possible transitions connecting any of the p 3He S- and P-wave channels to 4He are considered. The S factor at a p 3He center-of-mass energy of 10 keV is predicted to be 10. 1x10(-20) keV b, a factor of approximately 4.5 larger than the value adopted in the standard solar model. The P-wave transitions are found to contribute about 40% of the calculated S factor.

Journal Article↗

PubMed1996