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Elastic p- 3 H scattering below the n- 3 He threshold. Why 4N scattering?. Few-nucleon systems: present the most natural testground for the inter-nucleon interaction models Present interaction models (>70 years of research): Phenomenological (INOY,ISUJ,..)
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Why 4N scattering? • Few-nucleon systems: present the most natural testground for the inter-nucleon interaction models Present interaction models (>70 years of research): • Phenomenological (INOY,ISUJ,..) • Meson exchange theory (Nijm, AV18, CD-Bonn,…) • Chiral perturbation theory (Idaho, Epelbaum,…) • 2N is made to work with perfect fits (c2/data~1.) and several parameters • 3N problems begin, requires one more fit to fix energies (3N-Force), no effective remedies for some scattering observables • Beyond 3N: the most accessible testground A=3-12 bound states, but not easy to find uncorelated observables
Why 4N scattering? • Ab-initio calculations very limited beyond A=4 system: first very promising calculations exist using GFMC (K. Nollett et al.), NCSM (S. Quaglioni on friday) and RGM (previous talk) require benchmarking. • A=4 scattering below break-up threshold became accessible and well established using ab-initio methods: FY, AGS (A. Deltuva et al.), HH (M. Viviani et al.) as well as RGM (H.M. Hofmann et al.) • Very rich dynamics of 4N
y y z z x x Reality is finite. Convergence Basis is infinite 3 3 2 2 4 4 1 1 Why 4N scattering? • Faddeev-Yakubovski (FY) equations in configuration space • Solution is searched by decomposing FY components in the partial wave basis • Radial parts of the amplitudes are developed in the spline basis, converting differential equations into linear algebra problem. • Extensions are made to incorporate 3NF and Coulomb interaction
No Coulomb B=]0.04-0.26[ MeV 4He continuum Becomes a bound state!!! 0-
jy jy jz lz jx jx 3 3 2 2 4 4 1 1 p-3H scattering/convergence INOY potential jmax=max(jx,jy,jz) n+3He 0.76 MeV 0+ p+3H
p-3H scattering lengths n+3He 0.76 MeV 0+ p+3H
p-3H scattering below n-3He threshold qc.m.=120° Exp: Balashko et al., Sov. Phys. JETP 9 (1959) 137; Jarmie et al., Phys. Rev 130 (1963)1987; Ennis et al., Phys. Rev. 95 (1954) 772
p-3H scattering below n-3He threshold qc.m.=120° Exp: Balashko et al., Sov. Phys. JETP 9 (1959) 137; Jarmie et al., Phys. Rev 130 (1963)1987; Ennis et al., Phys. Rev. 95 (1954) 772
p-3H scattering below n-3He threshold Ep=900 keV Ep=300 keV Exp: Y. G. Balashko et al., Journ. Izv. Rossiiskoi Akademii Nauk, Ser. Fiz. 28 (1964) 1124; Proc. Nuclear Physics Congress, Paris (1964) 255
Conclusion • Accurate theoretical calculations for 4N scattering are now available • Continuum of 4He turns to be a rich laboratory to test NN & NNN interactions: revealing some discrepencies already for 0+ state • More experiments in 4N sector and in particular for low energies will be very appreciated Acknowledgements:The numerical calculations have beenperformed at IDRIS (CNRS, France). We thank the staff members of the IDRIScomputer center for their constant help.