No-core shell model in an effective-field-theory framework

• Published in: Physics letters. B Vol. 653; no. 2; pp. 358 - 362
• Main Authors: Stetcu, I., Barrett, B.R., van Kolck, U.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30-09-2007; Elsevier Science
• Subjects: Exact sciences and technology; Nuclear physics; Physics; The physics of elementary particles and fields; 24.10.Cn; 45.50.Jf; 21.30.-x; 21.60.Cs; Effective field approximation; Shell models; Frequency dependence; Ground states; Binding energy; Nucleons; Excited states; Harmonic oscillators
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2007.07.065

We present a new approach to the construction of effective interactions suitable for many-body calculations by means of the no-core shell model (NCSM). We consider an effective field theory (EFT) with only nucleon fields directly in the NCSM model spaces. In leading order, we obtain the strengths of the three contact interactions from the condition that in each model space the experimental ground-state energies of
2H,
3H and
4He be exactly reproduced. The first
(
0
+
;
0
)
excited state of
4He and the ground state of
6Li are then obtained by means of NCSM calculations in several spaces and frequencies. After we remove the harmonic-oscillator frequency dependence, we predict for
4He an energy level for the first
(
0
+
;
0
)
excited state in remarkable agreement with the experimental value. The corresponding
6Li binding energy is about 70% of the experimental value, consistent with the expansion parameter of the EFT.