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Constraints on symmetry energy and the n/p effective mass splitting

Constraints on symmetry energy and the n/p effective mass splitting. Symmetry energy:. Besides depending on the nuclear density , the symmetry energy also depends on the momentum or energy of a nucleon . S( r,k )= K+S_loc (r)+ S_nlc ( r,k ).

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Constraints on symmetry energy and the n/p effective mass splitting

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  1. Constraints on symmetry energy and the n/p effective mass splitting

  2. Symmetry energy: Besides depending on the nuclear density, the symmetry energy also depends on the momentum or energy of a nucleon. S(r,k)=K+S_loc(r)+S_nlc(r,k) Very different predictions for the momentum dependence of the nuclear symmetry potential. For cold nuclear matter

  3. Challenges on the constraints on symmetry energy: Constraint on symmetry energy from N-Star is smaller than from HICs Constraints from different transport models are not consistent Constraints from nuclear structure studies Addressing these challenges requires a good candidate that can connect the studies in HICs, nuclear structure and neutron-star models.

  4. Best choice, transport model However, there are two defaults: use different interaction form or parameters in HICs, structure and n-star studies In the transport model simulations, E0, K0, S0, L, m*… are changed un-correlated. It could cause some mis-leading results. How to understand and solve it? 1, develop new version of transport codes, which can use the same interactions (or energy density) as in structure and n-star studies. 2, And the coefficients of E0, K0, S0, L and m* are changed consisitently.

  5. Density dependence of symmetry energy, effective mass and Lane potential

  6. DR(n/p) and isospin diffusion depend on: Not only the local part, but also nonlocal part (effective mass splitting) in symmetry potential MDI: tends to change the momentum of nucleons from beam directions to transverse direction. Thus, we can find the MDI contributions by analyzing 1, n/p vs pt 2, n/p for transverse emitted nucleons with high kinetic energy

  7. Charge distribution

  8. n/p and DR(n/p) ratios as a function of kinetic energy

  9. Isospin transport ratio SLy4, because mn*<mp*, the isospin dependent MDI drive the reaction system reach the isospin equilibrium faster.

  10. Conclusion 1, n/p ratios of transverse emitted nucleons at high pt or high kinetic energy are sensitive to the effective mass splitting 2, calculations show that DR(n/p) not only depend on S0 and L, but also on the n/p effective mass splitting 3, The DR(n/p) and isospin diffusion data support the SLy4 parameter set, S0=32, L=46, Ksym=-120, m*/m=0.69 and mn*<mp*. This conclusion is close to the results obtained from N-STAR (Steiner12),

  11. Charge distribution Skz-1 is ruled out: neutron effective mass increase with density increasing for PNM, largest $\eta$ values in the \beta term, stronger repulsive at high density region. Also has been ruled out in J Margueron, PRC66,014303(2002)

  12. n/p ratios vs pt (-0.3<y^0<0.3) At high pt, the mn*<mp* cause the emitted nucleons with larger n/p ratios

  13. DR(n/p) ratios vs pt

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