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## Medium-modified NN interactions

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**Medium-modified NN interactions**Jeremy W. Holt* Nuclear Theory Group State University of New York * with G.E. Brown, J.D. Holt, and T.T.S. Kuo J.W. Holt**Medium-modified**Microscopic Foundation for density-dependent interactions Can such interactions provide a good description of nuclear systems? J.W. Holt**Chiral Effective Theories (e.g. Hidden Local Symmetry)**(1) Finite nuclei (2) Nuclear matter (3) Hot/dense matter Double Decimation Describe in a unified way G. Brown and M. Rho, Phys. Rept. 396 (2004) Chiral decimation QCD Match T and dependence with QCD Sum Rule correlation functions Fermi liquid decimation EFT with intrinsic T and dependence Low-momentum interaction Traditional OBE potentials (e.g. Bonn, Nijmegen, etc.) Introduce medium modifications “by hand” J.W. Holt**In-medium modifications (T = 0, 0)**Change in mass at = 0TheoryExperimentUs , ~ 10 – 15% decrease Yes Yes 15% ~ small increase Yes Yes 0% ~ 10% decrease Yes No 7% Assume linear scaling: J.W. Holt**Traditional problem: Strong short distance repulsion**(a) G-matrix RG and EFT (b) Vlow-k J.W. Holt**Bare NN Potentials**Universal interaction for = 2.1 fm-1 k = 2.1 fm-1 Elab = 350 MeV Integrate out the experimentallyunconstrained part of the NN interaction J.W. Holt**Outline of Results**• Nuclear matter • Easier than finite nuclei (only one density) • Saturation (E/A, kF, K ) • Hartree-Fock (preliminary) • Ring diagram expansion (preliminary) • Fermi liquid theory [JWH et al., NPA 785 (2007) 322.] • Finite nuclei • Diminishing tensor force • Beta decay of 14C J.W. Holt**Saturation with low momentum interactions**Fixed cutoff in Hartree-Fock approximation (no saturation) Empirical saturation energy and density Add leading order chiral 3N force S. Bogner et al., NPA 763 (2005) 59. J.W. Holt**Tensor force with dropping masses**J.W. Holt**Hartree-Fock**+ Preliminary! Novel saturation mechanism J.W. Holt**Ring diagrams (pp)**+ + + Introduce model space m ~ 3.0 fm –1 Choose vlowk = m J.W. Holt**Preliminary!**[MeV] [fm–1] J.W. Holt**Fermi Liquid Theory**Weakly interacting quasiparticles Strongly interacting, normalFermi systems at T = 0 Quasiparticles defined only near Fermi surface:k kF Expand: quasiparticle interaction Hartree-Fock J.W. Holt**Spin & Isospin Dependence:**Dimensionless parameters: Correspondence between FLP and observables J.W. Holt**Babu-Brown induced interaction**S. Babu and G. Brown, Ann. Phys. 78 (1973) 1 + Pauli Principle Sum Rules: J.W. Holt**Driving Terms (Vlow-k CD-Bonn)**Full Calculation: Fd0= -1.20 Fd1= -0.50 Gd0= 0.14 Gd1= 0.24 F'd0= 0.35 F'd1= 0.26 G'd0= 0.60 G'd1= 0.12 Unstable (negative K) Rapid convergence of iteration scheme Sum Rules: Largest effect is to cut down the strong attraction in F channel J.W. Holt**How to improve?**1. Explicit three-body forces 2. In-medium modifications to NN interaction Extend Walecka mean field theory to constituent quarks Medium modifications equivalent to a type of 3N force J.W. Holt**Full many-body calculations**gA = 1.25 gA* = 1.00 Decreasing g2wNN by 20% cuts K by 50% but changes other observables by ~ 5% quark model J.W. Holt**Finite nuclei**Decreasing tensor force necessary! • Decay of 14C • 0– T=1 and 0– T=0 splitting in 16O • E2 and M1 moments of 6Li Traditional many-body effects or novel scaling mechanism? J.W. Holt**14C**0+ 2 holes in 0p-shell – 1+ 14N Nijmegen I Preliminary J.W. Holt**Summary**• NN interactions with medium-modified mesons • Saturation of nuclear matter and Fermi liquid parameters improved with dropping masses Outlook • Full analysis of ring diagrams • Look for nuclear observables where tensor force plays dominant role • Understand the connection between medium modifications and three-body forces J.W. Holt