1. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 1 Zebo Tang, USTC Zebo Tang University of Science and Technology of China (USTC) Hypernucleus production at RHIC Introduction and Motivation Evidence for first antihypernucleus and signal (for discovery) Mass and lifetime measurement Production rate and ratios Yields as a measure of correlation (coordinate and momentum space) A case of low energy scan Conclusion and Outlook

2. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 2 Zebo Tang, USTC The first hypernucleus was discovered by Danysz and Pniewski in 1952. It was formed in a cosmic ray interaction in a balloon-flown emulsion plate. M. Danysz and J. Pniewski, Phil. Mag. 44 (1953) 348 M. Danysz and J. Pniewski, Phil. Mag. 44 (1953) 348 What are hypernuclei （超核） ? Hypernuclei of lowest A Y-N interaction: a good window to understand the baryon potential Binding energy and lifetime are very sensitive to Y-N interactions Hypertriton:  B=130±50 KeV; r~10fm Production rate via coalescence at RHIC depends on overlapping wave functions of n+p+   in final state Important first step for searching for other exotic hypernuclei (double-  ) No one has ever observed any antihypernucleus Nucleus which contains at least one hyperon in addition to nucleons.

3. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 3 Zebo Tang, USTC From Hypernuclei to Neutron Stars hypernuclei  -B Interaction Neutron Stars S=-1 S=-2 S=-0 Several possible configurations of Neutron Stars – Kaon condensate, hyperons, strange quark matter Single and double hypernuclei in the laboratory: – study the strange sector of the baryon-baryon interaction – provide info on EOS of neutron stars J.M. Lattimer and M. Prakash, "The Physics of Neutron Stars", Science 304, 536 (2004) J. Schaffner and I. Mishustin, Phys. Rev. C 53 (1996): Hyperon-rich matter in neutron stars Saito, HYP06

4. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 4 Zebo Tang, USTC Can we observe hypernuclei at RHIC?  In high energy heavy-ion collisions: – nucleus production by coalescence, characterized by penalty factor. – AGS data [1] indicated that hypernucleus production will be further suppressed. – What’s the case at RHIC?  Low energy and cosmic ray experiments (wikipedia): hypernucleus production via –  or K capture by nuclei – the direct strangeness exchange reaction hypernuclei observed – energetic but delayed decay, – measure momentum of the K and  mesons [1] AGS-E864, Phys. Rev. C70,024902 (2004)

5. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 5 Zebo Tang, USTC STAR Detector MRPC ToF barrel 100% for run 10 PMD FPD FMSFMS EMC barrel EMC End Cap DAQ1000 Take data FGT Complete Ongoing MTD (BNL LDRD) R&D HFT TPC Only TPC for this analysis

6. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 6 Zebo Tang, USTC Light nuclei at STAR STAR, arXiv:0909.0566 Clearly identified using dE/dx (TPC) Plentiful of light (especially anti)-nuclei RHIC: the best antimatter machine!

7. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 7 Zebo Tang, USTC Hyperon at STAR STAR PRL 89 (2002) 132301 Secondary vertex finding technique Spatial resolution w/o silicon (TPC only): Primary vertex: few hundred  m in Au+Au Secondary vertex: few mm Excellent capability for strange particle reconstruction

8. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 8 Zebo Tang, USTC Data-set and track selection Data-set used, Au+Au 200 GeV  ~67M Run7 MB,  ~23M Run4 central,  ~22M Run4 MB,  |VZ| < 30cm Track quality cuts, global track  nFitsPts > 25 nFitsPts/Max > 0.52  nHitsdEdx > 15  P t > 0.20, |  | < 1.0  Pion n-sigma (-2.0, 2.0)  DCA of v0 to PV < 1.2 cm  DCA of  to PV > 0.8 cm  DCA of  to 3 He < 1.0 cm  Decay length > 2.4 cm 3  H mesonic decay, m=2.991 GeV, B.R. 25%;

9. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 9 Zebo Tang, USTC 3 He & anti- 3 He selection Select pure 3 He sample: -0.2 2 GeV 3 He: 2931(MB07) + 2008(central04) + 871(MB04) = 5810 Anti- 3 He: 1105(MB07) + 735(central04) + 328(MB04) = 2168

10. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 10 Zebo Tang, USTC A candidate event at STAR Run4 (2004) 200 GeV Au+Au collision

11. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 11 Zebo Tang, USTC signal from the data  background shape determined from rotated background analysis;  Signal observed from the data (bin-by-bin counting): 157 ± 30 ;  Projection on antihypertriton yields: constraint on antihypertriton yields without direct observation STAR Preliminary

12. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 12 Zebo Tang, USTC  Signal observed from the data (bin-by-bin counting): 70±17; Mass: 2.991±0.001 GeV; Width (fixed): 0.0025 GeV; signal from the data STAR Preliminary

13. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 13 Zebo Tang, USTC Combine hypertriton and antihypertriton signal: 225 ± 35 Combined signals STAR Preliminary This provides a >6  signal for discovery

14. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 14 Zebo Tang, USTC Lifetime  Our data:  Consistency check on  lifetime yields  (  )=267±5 ps [PDG: 263 ps]. STAR Preliminary

15. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 15 Zebo Tang, USTC Comparison to world data  Lifetime related to binding energy  Theory input: the  is lightly bound in the hypertriton [1] R. H. Dalitz, Nuclear Interactions of the Hyperons (Oxford Uni. Press, London, 1965). [2] R.H. Dalitz and G. Rajasekharan, Phys. Letts. 1, 58 (1962). [3] H. Kamada, W. Glockle at al., Phys. Rev. C 57, 1595(1998). STAR Preliminary

16. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 16 Zebo Tang, USTC Measured invariant yields and ratios In a coalescence picture: 0.45 ~ (0.77) 3 STAR Preliminary

17. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 17 Zebo Tang, USTC Yields/ratios as a measure of correlation uud udd udu uud udd uud udd uds 3 Het 3H 3H Wave function overlaping Coalescence Yield depends on the correlation in both coordinate and momentum space ( 3 He, t, 3  H)  (u, d, s)+4u+4d A simple and perfect system! 3  H/ 3 He ratio  Lambda-nucleon correlation 3 He/t ratio  charge-baryon correlation

18. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 18 Zebo Tang, USTC Yields/ratios as a measure of correlation measurements related to local (strangeness, baryon) - baryon correlation Lattice Simulations of (all strangeness) - (all baryon) correlation at zero chemical potential STAR Preliminary

19. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 19 Zebo Tang, USTC Search for onset of deconfinement Hypertriton only STAR: DAQ1000+TOF Beam energy200(30—200) GeV~17 (10—30)GeV~5 (5-10) GeV Minbias events# (5  ) 300M~10—100M~1—10M Penalty factor144836848 3 He invariant yields1.6x10 -6 2x10 -4 0.01 3  H/ 3 He assumed1.00.30.05 S. Zhang et al., arXiv:0908.3357 [nucl-ex] AMPT (string melting) (default)

20. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 20 Zebo Tang, USTC / 3 He is 0.82 ± 0.16. No extra penalty factor observed for hypertritons at RHIC. Strangeness phase space equilibrium  The / 3 He ratio is determined to be 0.89 ± 0.28, and  The lifetime is measured to be  Consistency check has been done on analysis; significance is ~5   has been observed for 1 st time; significance ~4 . Conclusions  The / ratio is measured as 0.49±0.18, and 3 He / 3 He is 0.45±0.02, favoring the coalescence picture.

21. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 21 Zebo Tang, USTC Outlook Lifetime: –data samples with larger statistics (~factor 10 more within a few years) Production rate: –baryon-strangeness correlation – a case for energy scan – establish trend from AGS-SPS-RHIC-LHC 3  H  d+p+  channel measurement: d-identification via TOF. Search for other hypernucleus: 4  H, 4  He, 4  H, 3  H, Search for anti-   RHIC: best antimatter machine ever built

22. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 22 Zebo Tang, USTC Extend to the sector of strangeness and antimatter

23. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 23 Zebo Tang, USTC Hypernucleus at CSR energy C+C 1 GeV C+C 2 GeV Ca+Ca 1 GeV Ca+Ca 2 GeV p11.98611.69239.94037.758  0.00010.00790.00120.0399 3 He0.01 0.150.11 3H3H3e-87e-71e-6 1e-5 Song Zhang (SINAP), ART + Coalescence 100 in 100M Ca+Ca @ 1 GeV (~ Au+Au @ RHIC top energy) But in few seconds Basic detectors: Dipole, tracking, TOF and neutron wall

24. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 24 Zebo Tang, USTC Hypernucleus at higher energy A. Andronic, P. Braun-Munzinger, J. Stachel, Nucl. Phys. A 772 (2006) 167. P. Braun-Munzinger, J. Stachel, J. Phys. G 21 (1995) L17 A. Andronic: SQM09 Smaller penalty factor, higher strangeness production rate

25. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 25 Zebo Tang, USTC PANDA at FAIR 2012~ Anti-proton beam Double  -hypernuclei  -ray spectroscopy MAMI C 2007~ Electro-production Single  -hypernuclei  -wavefunction JLab 2000~ Electro-production Single  -hypernuclei  -wavefunction FINUDA at DA  NE e + e - collider Stopped-K - reaction Single  -hypernuclei  -ray spectroscopy (2012~) J-PARC 2009~ Intense K - beam Single and double  -hypernuclei  -ray spectroscopy  HypHI at GSI/FAIR Heavy ion beams Single  -hypernuclei at extreme isospins Magnetic moments SPHERE at JINR Heavy ion beams Single  -hypernuclei Basic map from Saito, HYP06 International Hyper-nuclear network BNL Heavy ion beams Anti-hypernuclei Single  -hypernuclei Double  -hypernuclei CBM? CSR?

26. CBM-China Meeting, Tsinghua U., Nov. 2-5, 2009 26 Zebo Tang, USTC Acknowledgement Thank my STAR Collaborators for providing the perfect detectors and exciting results!