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Chiral Symmetry and Isospin Symmetry at CSR Energy ZHUANG Pengfei (Tsinghua University)

Chiral Symmetry and Isospin Symmetry at CSR Energy ZHUANG Pengfei (Tsinghua University). ● Friedel Oscillation at High Baryon Density. ● M ass-splitting Induced Ratio at CSR Energy. known difference between T and.

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Chiral Symmetry and Isospin Symmetry at CSR Energy ZHUANG Pengfei (Tsinghua University)

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  1. Chiral Symmetry and Isospin Symmetry at CSR Energy ZHUANG Pengfei (Tsinghua University) ● Friedel Oscillation at High Baryon Density ● Mass-splitting Induced Ratio at CSR Energy

  2. known difference between T and both T and can induce QCD phase transitions ● T effect (in early universe and at RHIC and LHC): continuous change, second order phase transition, reliable lattice simulation ● effect (in compact stars and at CSR and FAIR): sudden jump, first order phase transition, model calculation partial chiral restoration in normal nuclear matter:

  3. bound states at high density ● ultracold atom gas: from recent experiment for highly imbalanced Fermi gas, the di-fermion bound states can survive in the symmetry restoration phase. C.H.Schunck et al., Science 316, 867(2007) ● relativistic heavy ion collisions: sQGP above the phase transition Shuryak, Zahed,2004 ★ ? NJL calculation, Jin, He, Zhuang, 2005

  4. Friedel oscillation by sharp Fermi surface Yukawa potential (1934-1935): integration over boson momentum fermion distribution: Friedel oscillation Friedel oscillations in nuclear matter(Alonso, et al., 1989,1994), hadronic matter (Mornas et al., 2001), and quark matter (Flambaum, Shuryak, 2007).

  5. quark potential in a quark-meson plasma Mu, Zhuang, EPJC, 2008 SU(2) NJL model: order parameter of chiral phase transition: S: mean field quark propagator quark-quark scattering diagram in RPA : mesons meson polarization function :

  6. Friedel Oscillation the Friedel oscillation is important at high matter density and low temperature.

  7. remarkable potential at extremely high density the potential becomes saturated and approaches zero at T/T_c = 3, namely the quark system is weakly coupled at high enough temperature. the potential does not approach zero even at extremely high matter density ! There will be a wide bound state region at high density.

  8. strongest coupling at critical density Shuryak, Zahed, 2004 large ratio means strong coupling, and small ratio indicates weak coupling maximum coupling at the chiral phase transition !

  9. Conclusion density effect is quite different from temperature effect in QCD phase structure, and there is a wide quark-bound-state region at high density. Questions are quark stars located in this strongly coupled quark-hadron region? if there exists such a quark-hadron region at FAIR and CSR, what are the signatures?

  10. isospin symmetry breaking ● isospin asymmetric nuclear collisions:Au-Au at 1 A GeV (SIS/GSI) N / Z = 118 / 79 U-U at 0.6 A GeV (CSR/Lanzhou) N / Z = 146 / 92 ●isospin symmetry at finite T and : explicit and spontaneous isospin symmetry breaking, pion superfluidity (negative !) 何联毅,郝学文,金猛,庄鹏飞: PRD75:096004,2007；PLB652:275,2007；PRD74:036005,2006 PRD71:116001,2005；PLB615:93,2005

  11. pion mass splitting isospin induced mass splitting,Goldstone mode ● which final state distribution is sensitive to the isospin symmetry breaking? ratio ! experiment data for Au-Au at 1 A GeV: A.Wagner et al., PLB 420(1998)20. isobar model which is valid around 1 A GeV: R.Stock, Phys. Rep. 135(1986)259.

  12. momentum dependence ●kinetic energy dependence of A.Wagner et al., PLB 420(1998)20 much larger than 1 close to 1 the energy dependence disappears at high energy and in peripheral collisions. the energy dependence is explained by (variable) Coulomb potential between charged pions and the nuclear matter M.Gyulassy, S.K.Kauffmann, NPA 362(1981)503; Bao-an Li, PLB 346(1995)5, PRC 67(2003)017601; A.Wagner et al., PLB 420(1998)20; …... ●our idea: we self-consistently explain the energy dependence of in the frame of isospin symmetry breaking. isospin-induced mass splitting light particles are easily created at low momentum and heavy particles are hard to be produced.

  13. thermal production ● particles ( ) are statistically emitted at freeze-out, for particles emitted from central rapidity region, 5 parameters: are determined by particle spectra and they are well-known, is determined by the ratio for Au-Au at 1 A GeV ●particle masses cab be calculated via effective models, such as NJL, linear sigma model, and chiral perturbation theory, the results are almost the same.

  14. numerical result Hao, Xiao, Zhuang, 2008 ● preliminary numerical results our predicition for U-U at 0.6 A GeV KAOS data for Au-Au at 1 A GeV our theoretical calculation ● summary the isospin symmetry breaking, especially the mass splitting, can self-consistently explain the ration and its energy dependence. we also calculated the ratio .

  15. an experimental support ● a support to our idea isospin symmetric collisions Ca-Ca: N/Z = 20/20 data: Coulomb explanation fails: there is still Coulomb potential, but the ratio is about 1 ! mass-splitting calculation works: for isospin symmetric systems, there is no mass splitting, and therefore we have always

  16. 肖志刚

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