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

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Presentation on theme: "Constraints on symmetry energy and the n/p effective mass splitting."— Presentation transcript:

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. Very different predictions for the momentum dependence of the nuclear symmetry potential. S(r,k)=K+S_loc(r)+S_nlc(r,k) For cold nuclear matter

3 1. Constraint on symmetry energy from N- Star is smaller than from HICs 2.Constraints from different transport models are not consistent 3.Constraints from nuclear structure studies Challenges on the constraints on symmetry energy: Addressing these challenges requires a good candidate that can connect the studies in HICs, nuclear structure and neutron-star models.

4 However, there are two defaults: 1. use different interaction form or parameters in HICs, structure and n-star studies 2.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. Best choice, transport model

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7 Para.E0E0 K0K0 Q0Q0 JLK sym m*/m SLy40.16-15.97229.91363.113246-1200.69<1 SkI20.158-15.78240.93339.7033104710.68<1 SkM*0.16-15.77216.61386.093046-1560.79>1 Gs0.158-15.59237.29348.793193140.78>1 NRAPR0.16-15.85225.65362.543360-1230.69>1 Small LLarge L m_n*<m_p*SLy4SkI2 m_n*>m_p*SkM*Gs

8 Density dependence of symmetry energy, effective mass and Lane potential

9 DR(n/p) and isospin diffusion depend on: 1.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

10 Charge distribution

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

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

13 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 S 0 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, S 0 =32, L=46, Ksym=-120, m*/m=0.69 and mn*<mp*. This conclusion is close to the results obtained from N-STAR (Steiner12),

14 Skz-1 is ruled out : 1. neutron effective mass increase with density increasing for PNM, 2. largest $\eta$ values in the \beta term, 3. stronger repulsive at high density region. Also has been ruled out in J Margueron, PRC66,014303(2002) Charge distribution

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17 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

18 DR(n/p) ratios vs pt


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