The three-nucleon system near the N-d threshold

Abstract

The three-nucleon system is studied at energies a few hundred keV above the N-d threshold. Measurements of the tensor analyzing powers T 20 and T 21 for p-d elastic scattering at E c.m. = 432 keV are presented together with the corresponding theoretical predictions. The calculations are extended to very low energies since they are useful for extracting the p-d scattering lengths from the experimental data. The interaction considered here is the Argonne V18 potential plus the Urbana three-nucleon potential. The calculation of the asymptotic D-to S-state ratio for 3 H and 3 He, for which recent experimental results are available, is also presented.

Precision calculation of the quartet-channelp−dscattering length

“…A consistent treatment of screening effects is crucial for a stable and reliable theoretical extraction of this quantity. Our result for the quartet pd scattering length, 4 a p-d = (10.9 ± 0.4) fm, agrees with older experimental determinations of this quantity but deviates from potential-model calculations and a more recent result from Black et al, which find larger values around 14 fm [1][2][3][4].…”

“…Including a new measurement of the p-d cross section performed at Triangle Universities Nuclear Laboratory (TUNL) for very low proton center-of-mass energies of only 163 and 211 keV, they extracted a value of 4 a p-d = (14.7 ± 2.3) fm. While this falls in line with theoretical extractions of the quantity based on potential-model calculations [2][3][4] that find values for 4 a p-d close to about 13.8 fm (see Table 1 in Ref. [1] for details), it deviates quite significantly from older experimental determinations of 4 a p-d that find values between (11.11 +0.25 −0.24 ) fm [5] and (11.88 +0.4 −0.1 ) fm [6] (cf.…”

“…A similar argument also holds for magnetic-moment or Mott-Schwinger interactions between the proton and the deuteron. This power counting is supported by the potential model calculation of Kievsky et al [4], which finds only small changes in the scattering length of order 0.05 fm when electromagnetic terms beyond the Coulomb interaction are included.…”

The proton–deuteron scattering length in pionless EFT

“…The most recent determination of this quantity, carried out by Black et al [1], extracts a value of 4 a p-d = (14.7 ± 2.3) fm. While this falls in line with theoretical extractions of the quantity based on potential-model calculations [2][3][4] that find values close to about 13.8 fm, it deviates quite significantly from older experimental results for 4 a p-d between 11 and 12 fm [5,6]. In this work, we present a theoretical calculation of 4 a p-d using pionless effective field theory (pionless EFT).…”

Erratum: Search for excited states in3Hand3He[Phys. Rev. C59, 1207 (1999)]

“…[5] experiment does not indicate an excited state. However, in a recent work [7] it was shown that the effective range function of the doublet d+p scattering has a singularity at a negative energy, just below the d + p threshold. This would indicate the existence of subthreshold virtual states in 3 He.…”