1

Zhangbu Xu （许长补）

Search for Exotic Particles

2

Strange Quark Matter

Low Charge-to-Mass Ratio|Z|/m<<1 (A=2 1057)

Hybrid states (H-d, q-p)Witten, PRD 30(1984)272Jaffe, PRL 38(1977)617E

n, e,

3

Why Strange Quark Matter?

QCD Allowed New States QCD Lab. (quarks&gluons) Future Energy Source Star Fates

4

Strangelet Production High energy

density and/or baryon density

Production models Coalescence

production Distillation of QGP Thermal production

Greiner, et al, PRD 38(1988) 2797Baltz, et al, PLB 325(1994) 7

P. Braun-Munzinger, et al, JPG 21(1995)L17

5

http://www.th.physik.unifrankfurt.de/~stoecker/vortrag2/strangelet.html

6

Strangelets (Small Lumps of Strange Quark Matter)

Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter.

• SQM is less stable for lower baryon

number (due curvature energy)

for A<~1000

• There are likely significant shell effects at low A.

E/A

(M

eV)

A

Bag model results with varying ms

values

7

Sources of Stable Strangelets?Relics of Early Universe? (Dark Matter?)

Skylab, TREK: Satellite based Lexan. No events Z>100 ARIEL-6, HEAO-3. scintillators, cerenkov counters. No

events Z>100 HECRO-81:Saito et al. scintillator, Cerenkov in balloon at

9gm/cm2. 2 Z=14 undercutoff events. A of 110(370) to be above cutoff(mean rigidity). E/A~.45 GeV

ET event Ichimura et. Al. emulstion chamber in balloon at few g/cm2 but trajectory would have taken it through ~200gm/cm2. Z~30. A measured at 460

Price monopole. Lexan and emulsions in balloon experiment. Constant ionization through Lexan and low number of delta rays for normal nucleus. One interperetation is Z=45 and mass of 1000-10000

Centauro (original) SLIM: mountaintop Lexan CR detector Fossil Tracks (in meteorites) Mica: look for tracks traversing 10**7 g/cm2 Mountaintop. Look for tracks traversing ~600 g/cm2 Sea Level:tracks traversing 10**3 g/cm2 Underground: tracks traversing 10**4 g/cm2 Centauro:1000Tev shower at 500g/cm2, mass~200. Small

em component (decay into strange baryons?) and very penetrating (SQM glob which isn’t destroyed by nuclear interactions?)

Ke Han: PRL 103 (2009) 092302 Lunar Soil

8E. Finch-SQM 2006

How to find stable strangelets? “Best” way: measure cosmic ray spectrum with

high precision spectrometer…AMS aboard the ISS

9

Limits on Strangelet Production

Also negatively charged, neutral

10

Zhangbu Xu （许长补） (for the STAR Collaboration)

Observation of and @ RHIC (观测反超氚核）

H3Λ H3

Λ

Introduction & Motivation

Evidence for first antihypernucleus– and signal (for discovery)

– Mass and Lifetime measurements

Production rate and ratios– Yields as a measure of correlation

– A case for RHIC energy scan

Conclusions and Outlook

H3Λ

H3Λ

11

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

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: DB=130±50 KeV; r~10fm

• Production rate via coalescence at RHIC depends on overlapping wave functions of n+p+L in final state

• Important first step for searching for other exotic hypernuclei (double-L)

No one has ever observed any antihypernucleus

Nucleus which contains at least one hyperon in addition to nucleons.

)(

)(3

3

pnH

pnH

12

from Hypernuclei to Neutron Stars

hypernuclei L-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

13

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 DANE• 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

Current hypernucleus experiments

14

Can we observe hypernuclei at RHIC?

Z.Xu, nucl-ex/9909012

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

– L or K capture by nuclei

– the direct strangeness exchange reaction

hypernuclei observed – energetic but delayed decay,– measure momentum of the K and p mesons

[1] AGS-E864, Phys. Rev. C70,024902 (2004)

|

聚并

15

A candidate event at STARRun4 (2004)

200 GeV Au+Au collision

16

3LH mesonic decay, m=2.991 GeV, B.R. 0.25;

Data-set used, Au+Au 200 GeV ~67M Run7 MB,~23M Run4 central,~22M Run4 MB, |VZ| < 30cm

Track quality cuts, global tracknFitsPts > 25, nFitsPts/Max > 0.52nHitsdEdx > 15

Pt > 0.20, |eta| < 1.0

Pion n-sigma (-2.0, 2.0)

Data-set and track selection

HeH

eHH33

33Secondary vertex finding

technique

DCA of v0 to PV < 1.2 cmDCA of p to PV > 0.8 cmDCA of p to 3He < 1.0 cmDecay length > 2.4 cm

17

3He & anti-3He selection

Select pure 3He sample: -0.2<Z<0.2 & dca <1.0cm & p >2 GeV 3He: 2931(MB07) + 2008(central04) + 871(MB04) = 5810

Anti-3He: 1105(MB07) + 735(central04) + 328(MB04) = 2168

)/

/ln( Bichsel

dxdE

dxdEZ

18

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

H3Λ

11595810/2168*157/HeH*H 333Λ

3Λ He

STAR Preliminary

19

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 dataH3Λ

STAR Preliminary

20

Combine hypertriton and antihypertriton signal: 225±35

Combined signals

STAR Preliminary

This provides a >6s signal for discovery

21

Lifetime

ps27182 8945 Our data:

Consistency check on L lifetime yields t(L)=267±5 ps [PDG: 263 ps].

STAR Preliminary

STAR Preliminary

22

Comparison to world data

Lifetime related to binding energy Theory input: the L 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

23

Measured invariant yields and ratios

)/()/(/

)/)(/)(/(/233

33

nnppHeeH

nnppHH

In a coalescence picture:

0.45 ~ (0.77)3

STAR Preliminary

24

Antinuclei in nature (new physics)

Dark Matter, Black Hole antinucleus production via coalescence

To appreciate just how rare nature produces antimatter (strange antimatter)

AMS antiHelium/Helium sensitivity: 10-9

RHIC: an antimatter machine

Seeing a mere antiproton or antielectron does not mean much– after all, these particles are byproducts of high-energy particle collisions.

However, complex nuclei like anti-helium or anti-carbon are almost never created in collisions.

25

What can we do with antimatterWeapon? Rocket propulsion

《天使与魔鬼》

26

hypernuclei and antimatter from correlations in the Vacuum

Real 3-D periodic tablePull from vacuum (Dirac Sea)

27

Matter and antimatter are not created equal

RHIC

SPS

)(5.0/

)(10/

10/

33

333

1133

RHICHeeH

SPSHeeH

HeeH

Nucl-ex/0610035

But we are getting there !

AGS

STAR PRL 87(2003)

NA52

(AGS,Cosmic)

物质和反物质造而不平等

28

Flavors (u,d, s) are not created equal except in possible QGP

J. Rafelski and B. Muller, Phys.Rev.Lett.48:1066,1982

STAR whitepaper, NPA757(2005)

29

Yields as a measure of correlation

A=2Baryon density <B>

A=3 <2B>; <LB>

S. Haussler, H. Stoecker, M. Bleicher, PRC73

UrQMD

UrQMD

Caution: measurements related to local (strangeness baryon)-baryon correlation Simulations of (all strangeness)—(all baryon) correlation

30

(3He, t, 3LH)(u, d,

s)

• A=3, a simple and perfect system 9 valence quarks, (3He, t, 3

LH)(u, d, s)+4u+4d

• Ratio measures Lambda-nucleon correlation

• RHIC: Lambda-nucleon similar phase space• AGS: systematically lower than RHIC

Strangeness phase-space equilibrium

• 3He/t measures charge-baryon correlation

STAR Preliminary

uud

uddudu

uud

uddudd

uud

udduds3He t 3

LH

31

: Primordial -B correlation

STAR Preliminary

Caution: measurements related to local (strangeness baryon)-baryon Lattice Simulations of (all strangeness)—(all baryon)

correlation correlation at zero chemical potential

A. Majumder and B. Muller, Phys. Rev. C 74 (2006) 054901

He33Λ H/

32

Energy scan to establish the trend

Hypertriton onlySTAR: DAQ1000+TOF

Beam energy 200(30—200) GeV ~17 (10—30)GeV ~5 (5-10) GeV

Minbias events# (5s) 300M ~10—100M ~1—10M

Penalty factor 1448 368 48

3He invariant yields 1.6x10-6 2x10-4 0.01

3LH/3He assumed 1.0 0.3 0.05

33

Hypernuclei sensitive to phase transition

AMPT Simulation of nucleon coalescence (with or w/o string melting):a) CBS is not sensitive to phase transitionb) Strangeness population from hypertriton sensitive to phase transition

34

/ 3He is 0.82 ± 0.16. No extra penalty factor observed for hypertritons at RHIC. Strangeness phase space equilibrium

The / 3He 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 ~5s

has been observed for 1st time; significance ~4s.

Conclusions

H3Λ

H3Λ

H3Λ H3

Λ

H3Λ

H3Λ

The / ratio is measured as 0.49±0.18, and

3He / 3He is 0.45±0.02, favoring the coalescence picture.

ps27182 8945

35

Outlook

Lifetime:– data samples with larger statistics

Production rate: – Strangeness and baryon correlation

Need specific model calculation for this quantity– Establish trend from AGS—SPS—RHIC—LHC

L3Hd+p+p channel measurement: d and dbar via ToF.

Search for other hypernucleus: 4LH, double L-hypernucleus.

Search for anti-a

RHIC: best antimatter machine

36

What can CSR contribute? CSR 12C, 40Ca ( GeV), At the threshold of K, L

production Perfect for hypernucleus production

Hypertriton lifetime, binding energy, absorption s Strangeness phase space population at CSR energies Exotic hypernuclei (proton/neutron rich, Sigma)

外靶实验装置适合超核重建 :Dipole, tracking, TOF and neutron wall

To do list: Tracking before Dipole (GEM, Silicon, MPWC) Model Simulations Detector Simulations Electronics and DAQ

5.2s

37

Vision from the past

The extension of the periodic system into the sectors of hypermatter (strangeness) and antimatter is of general and astrophysical importance. … The ideas proposed here, the verification of which will need thecommitment for 2-4 decades of research, could be such a vision with considerable attraction for the best young physicists… I can already see the enthusiasm in the eyes of young scientists, when I unfold these ideas to them — similarly as it was 30 years ago,… ---- Walter Greiner (2001)

38

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 DANE• 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 L-

hypernuclei

CSR at IMP?