Data from AR_93034_4.ens

The wavefunction for the triton bound state is calculated to be mostly s-state (approx. 90%) with s'-state (approx. 1%) and d-state (approx. 9%) admixtures depending on the potentials used (1986Is08,1979Sa15). See also 1983Fr19, 1984Mu23, 1980Ha10, 1984Ci05, 1984Ci09, 1989Lo09. The measured magnetic moment for ³H is μ=2.97896248 n.m. 7 (1996FiZX). Calculations which include both impulse and pion exchange contributions are in fairly good agreement with the measured trinucleon magnetic moments (1985To21). Calculations with a six-quark bag model (1986Bh05) are also compatible with the data for ³H and ³He (1982Wo03,1983Bu07).

The rms charge and magnetic radii for ³H determined from electron scattering are R_C=1.63 fm 3 and R_M=1.72 fm 6. In general two-body force calculations give values of R_C which are 10% too large (1986GiZS). This discrepancy has not yet been fully resolved by the addition of three-body forces although there are calculations (1986Is06) which, when extrapolated to give the correct triton binding energies, are in reasonable agreement with R_C(expt.). However the form factor problem remains (1986GiZS). See also 1985Fr12, 1985SaZG which examine the way in which the triton bound state observables scale with binding energy.

The binding energy of ³H is 8.481821 MeV 4(1997Au04). Many calculations have been done to predict the binding energy of ³H and ³He (see the reviews of 1986FrZU, 1986GiZS, 1984Fr16 and other references below). It is observed in 1986GiZS that two-body force calculations with realistic forces underbind ³H by about 1 MeV whereas calculations with three-body forces give binding energies too large by about 0.5 MeV, although it is pointed out (discussion in 1987Ti07) that three-body force calculations can give correct binding energies if the cut-off mass is taken to be 700 MeV.

Charge and magnetic form factors for ³H have been determined from electron scattering experiments. Measurements of Q² from 23 to 31 fm² are reported in 1985Ju01. The available data indicate that the magnetic form factor is similar to that for ³He which has a diffraction minimum at a higher value of Q than predicted by impulse approximation calculations. The isobar model of 1983St11 with meson-exchange currents satisfactorily accounts for the difference. See also 1986Sa07, 1986Sa08. Calculations of the charge form factor with two-body potentials are in serious disagreement with experiment for ³He in that the theoretical momentum transfer at the first minimum is too high, and the height of the second maximum is too low. However it is pointed out in 1987St09 that the ³H charge form factor is well described by theory if the correct pseudoscalar vector coupling for the pion-nucleon vertex is used in the calculation of exchange current contributions. For other calculations see those listed in 1987Ti07. The addition of a three-body force increases the calculated value of the charge form factor in the region of the second maximum by 50%, but a factor of three is needed (1986GiZS). The work of 1987Be30 reporting on measurements of ³H and ³He isoscalar and isovector form factors also reviews the extent of agreement between current theories and experiment.

The review of 1986FrZU notes that calculational techniques for the trinucleon system have progressed to the point where critical examinations of three-nucleon forces, relativistic effects of nucleon motion, and explicit non-nuclear degrees of freedom such as pions, isobars, quarks et cetera can be made with some confidence.

See 1987Ti07 for references related to three-body force effects, relativistic effects in the trinucleon bound state, the effects of including tensor forces in three-body calculations, the quark structure of the trinucleon and the effect of quark clusters on its ground state properties, trinucleon asymptotic normalization constants, binding energy calculations, etc.