1. The nature of compressed baryonic matter Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu Renxin Xu ( 徐仁新 ) School of Physics, Peking University ( ) Pulsar searching and timing with FAST “PKU Astrophysics Colloquium 2012” Oct. 21, 2012; Biejing

2. Introduction: what’s compressed BM? EoS of compressed BM: specu. & obs. To understand EoS by large telescope Conclusions Summary Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

3. 11 Introduction: what’s compressed BM? Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu Higgs Boson 13 Totally: 62  48 What is baryon: the standard model of particle physics Baryon (a quark) = 1/3

4. The particle has been the subject of a 45- year hunt to explain how matter attains its mass.

5. Introduction: what’s compressed BM?  ~10 0 cm~10 -8 cm~10 -13 cm.... {uud}{uud}{udd}{udd} A brief history about compressed baryonic matter … G. Gamow (~1930): incompressible liquid drop for atomic nuclei L. Landau (1932, before n): what if drops are concentrated by gravity? Landau’s idea of “gigantic nucleus” develops to normal NS model... What if the quark degree of freedom (and w & s int.) is not negligible? our answer: {u, d, s}, > 6 (rather than 3) grouped in a cluster in CBM. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

6. A rubber made of NM/SM All of the world's population Introduction: what’s compressed BM? Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

7. Introduction: what’s compressed BM? EoS of compressed BM: specu. & obs. To understand EoS by large telescope Conclusions Summary Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

8. EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu EoS of compressed BM: the mainstream … Alford (2004)

9. coupling between quarks? … DSE approach of NQCD A quark clustering phase? ? Clustering ← BEC ← BCS Xu 2009, JPG, 36, 064010 EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

10. ~ (1, 10) km conventional neutron star quark-cluster star Gravity-bound (weak binding) vs. Self-bound (strong) Atmosphere vs. {q-clusters, electron sea} Differences between NS & quark-cluster star? (Heiselberg, 2000)(Xu, 2011) EoS of compressed BM: specu. & obs.

11. Metal ball V.S. Quark-cluster star ions/nuclei E-M interaction strong/color one quark clusters A quark-cluster star looks like a big metal ball EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

12. A realistic quark cluster: H-dibaryon? H-particles in lattice QCD: Beane et al. [NPLQCD Collaboration], Phys. Rev. Lett. 106, 162001 (2011) Inoue et al. [HAL QCD Collaboration], Phys. Rev. Lett. 106, 162002 (2011) What if quarks are clustered as H-diabaryons in QS? Lai, Gao & Xu (arXiv:1107.0834) Interaction between H’s is mediated by  -  mesons: In-medium stiffening effect: Brown-Rho scaling modified. EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

13. A realistic quark cluster: H-star? M-R, M-  c M max -V 0 EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

14. A corresponding-state approach to … EoS of compressed BM: specu. & obs. Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu Wilczek (2007)   Dimensionless parameters: Corresponding state law EoS The results (Guo, Lai & Xu; arXiv1209.3688):

15. Introduction: what’s compressed BM? EoS of compressed BM: specu. & obs. To understand EoS by large telescope Conclusions Summary Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

16. To understand EoS by large telescope Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu 1, Timing (ToA): spin-behavior + space-time fluctuations + post-Newtonian orbital effects + binary parameter + ISM + planetary ephemeris + time standards/navigation? 2, Pulse profile: radiative process (magnetospheric activity) + ISM Key observables of radio pulsars Large radio FAST telescopes are certainly necessary to measure precisely these two.

17. To measure the mass of radio pulsars To measure the inertial of momentum of NS To find sub-ms radio pulsars … To understand EoS by large telescope Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu To know compressed BM by large telescope

18. (Sala et al. ApJ, arXiv:1204.3627) Lai & Xu (2009, N q = 18, U 0 = 100 MeV) (Lai & Xu 2009 MNRAS, 398, L31) Demorest et al. (2010) PSR J1614 To understand EoS by large telescope

19. Introduction: what’s compressed BM? EoS of compressed BM: specu. & obs. To understand EoS by large telescope Conclusions Summary Compressed baryonic matter http://vega.bac.pku.edu.cn/rxxu R. X. Xu

20. Conclusions Pulsars are not only extreme labs of gravity, but also of the fundamental strong interaction. As manifestation of compressed baryonic matter, pulsars are sending us message being essential for us to know non-perturbative QCD. We are suggesting: realistic compressed baryonic matter at a few nuclear densities is composed by quark-cluster matter. Thanks!