Anti-hypernuclei production and search for P-odd domain formation at RHIC Gang Wang ( for the STAR...
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Anti-hypernuclei production and search for P-odd domain formation at RHIC Gang Wang ( for the STAR Collaboration ) UCLA A colored and flavored system in
Anti-hypernuclei production and search for P-odd domain
formation at RHIC Gang Wang ( for the STAR Collaboration ) UCLA A
colored and flavored system in collision...
Slide 2
2 Outline N Z S Exotic particleExotic phenomenon
Slide 3
3 No one has ever observed any anti- hypernucleus before us
(STAR). The first hypernucleus was discovered by Danysz and
Pniewski in 1952, 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 p
+ - (64%); n + 0 (36%) What is a hypernucleus? Hypernuclei of
lowest A A nucleus containing at least one hyperon in addition to
nucleons.
Slide 4
4 Hypernuclei: ideal lab for YN and YY interaction
Baryon-baryon interaction with strangeness sector Input for theory
describing the nature of neutron stars Coalescence mechanism for
production: depends on overlapping wave functions of Y+N at final
stage Anti-hypernuclei and hypernuclei ratios: sensitive to
anti-matter and matter profiles in HIC Extension of the nuclear
chart into anti-matter with S [1] [1] W. Greiner, Int. J. Mod.
Phys. E 5 (1995) 1 Why (anti-)hypernuclei?
Slide 5
5 International Hyper-nuclear network 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 BNL Heavy ion
beams Anti-hypernuclei Single -hypernuclei Double -hypernuclei
Slide 6
6 RHIC PHENIX STAR AGS TANDEMS Animation M. Lisa Relativistic
Heavy Ion Collider (RHIC)
Slide 7
7 Relativistic Heavy-ion Collisions initial stage
pre-equilibrium QGP and hydrodynamic expansion hadronization and
freeze-out New state of matter: QGP RHIC creates hot and dense
matter, containing equilibrium in phase space population of u, d
and s: ideal source of hypernuclei about equal numbers of q and
anti-q: ideal source of anti-nuclei RHIC white paper: Nucl. Phys. A
757
Slide 8
8 STAR Detector STAR consists of a complex set of various
detectors, a wide range of measurements and a broad coverage of
different physics topics.
Slide 9
9 Event display STAR TPC: an effectively 3-D ionization camera
with over 50 million pixels.
Slide 10
10 3 H mesonic decay, m=2.991 GeV/c 2, B.R. 0.25 Data-set used,
Au+Au 200 GeV ~67M year 2007 minimum-bias ~22M year 2004
minimum-bias ~23M year 2004 central, |V Z | 0.8 cm DCA of p to 3 He
< 1.0 cm Decay length > 2.4 cm QM09 proceeding:
arXiv:0907.4147
Slide 11
11 3 He & anti- 3 He selection Select pure 3 He sample: 3
He: 5810 counts anti- 3 He: 2168 counts condition: -0.2 2 GeV/c
Theory curve: Phys. Lett. B 667 (2008) 1
Slide 12
12 signal from the data Signal observed from the data
(bin-by-bin counting): 157 30 Mass: 2.989 0.001 0.002 GeV; Width
(fixed): 0.0025 GeV. Projection on anti-hypertriton yield:
=157*2168/5810= 59 11 STAR Collaboration, Science 328 (2010)
58
Slide 13
13 Signal observed from the data (bin-by-bin counting): 70 17
Mass: 2.991 0.001 0.002 GeV; Width (fixed): 0.0025 GeV. signal from
the data Projection on anti-hypertriton yield: 59 11 STAR
Collaboration, Science 328 (2010) 58
Slide 14
14 Combined the signal Combined hyperT and anti-hyperT signal :
225 35 It provides a >6 significance for discovery. STAR
Collaboration, Science 328 (2010) 58
Slide 15
15 Measure the lifetime ps We measure = 267 5 ps PDG value =
263 2 ps PDG: Phys. Lett. B 667 (2008) 1 STAR Collaboration,
Science 328 (2010) 58
17 A case for energy scan RHIC is carrying out Beam Energy Scan
as we speak. Baryon-strangeness correlation via hypernuclei: a
viable experimental signal to search for the onset of
deconfinement. model calculation: S. Zhang et al, Phys. Lett. B684,
224(2010) Baryon-strangeness correlation: PRL 95 (2005) 182301, PRC
74 (2006) 054901, PRD 73 (2006) 014004. Phase diagram plot:
arXiv:0906.0630 STAR Collaboration, Science 328 (2010) 58
Slide 18
18 The measured lifetime is ps, consistent with free lifetime
(263 ps) within uncertainty. Consistency check has been done on
analysis; 157 candidates, with significance better than 5 has been
observed for first time; 70 candidates, with significance ~4 .
Summary I The / ratio is measured as 0.49 0.18 0.07, and 3 He / 3
He is 0.45 0.02 0.04, favoring coalescence. RHIC is the best
anti-matter machine ever built!
Slide 19
19 Outlook Lifetime: 10 times more data within this year
Production rate: baryon-strangeness correlation a case for energy
scan establish a trend from AGS-SPS-RHIC-LHC 3 L H d+p+p channel
measurement: d-identification via ToF. Search for other
hypernucleus: 4 L H, 4 L He, 4 LL H, 3 X H, Search for anti-
AGS-E906, Phys. Rev. Lett. 87, 132504 (2001)
Slide 20
20 Looking into a mirror, you see someone else Its a parity
violation?! Parity transformation: A spatial inversion of the
coordinates. Origins of parity violation: 1. Global parity
violation Occurs in weak interactions Confirmed 2. Local parity
violation Predicted in strong interactions we are working on it
Kharzeev, PLB 633 260 (2006) [hep-ph/0406125]; Kharzeev, McLerran,
Warringa, NPA 803 227 (2008); Kharzeev, Zhitnitsky, NPA 797 67
(2007); Fukushima, Kharzeev, Waringa, PRD 78, 074033. Parity
violation
Slide 21
21 P/CP invariance are (globally) preserved in strong
interactions: neutron EDM (electric dipole moment)
experiments:
33 Systematic check: p T gap The non-zero same-sign correlator
for p T gap > 200 MeV/c indicates that we are safe from HBT or
Coulomb effects. STAR Preliminary
Slide 34
34 More checks from TPC EP We have looked at lower beam energy
(62 GeV) and/or smaller system (Cu+Cu), to see qualitatively
similar results. STAR Collaboration, arXiv:0909.1717
Slide 35
35 Summary II The formation of (local) meta-stable P-odd
domains in heavy-ion collisions is predicted to lead to charge
separation w.r.t the reaction plane. P-even correlator has been
measured with event planes from both STAR TPC and ZDC; and the
results are consistent! The gross feature of the correlator meets
the expectation for the picture of local Parity Violation: charge
separation, suppression of OS by opacity, weaker OS signal in
central collisions, OS&LS symmetry in peripheral collisions...
STAR has checked the possible effects on v 1, a 1, gap, and p T
gap.
Slide 36
36 Interpretations - + RP + - Out-of-Plane Charge Separation
Interpretation 1: RP Flowing structures Interpretation 2: X X X X X
X X = unknown structure Implies Local P-violation of strong
interactions Does Not Imply P violation of the strong
interactions
Slide 37
37 Interpretation 2 -+ RP +- charge conservation/cluster + v 2
Scenario 1: Scenario 2: Need some investigation -+ RP +- -+ charge
conservation/cluster + v 1 symmetry fluctuation STAR Collaboration,
PRL103 (2009)251601
Slide 38
38 Alternative measurements These observables contain all
possible (mixed) harmonic terms, while the correlator observables
previously shown contain only one. Charge asymmetry
correlation
Slide 39
39 Alternative measurements STAR preliminary d+Au Same-sign: -
A 2 UD > A 2 LR - meets LPV expectation - A 2 < 0 in central
collisions Oppo-sign: - aligned (A + A - > 0) - local charge
conservation? - A + A - UD > A + A - LR - contradicts LPV
expectation? - not dominantly RP-related Different observables have
different sensitivities to the charge separation, and suffer
different backgrounds. No real reaction plane here!
Slide 40
40 Outlook With zero net charge, the neutral particles are
expected to be much less affected by the electric field. , K s 0 et
al. Beam energy below QGP threshold Beam Energy Scan Isobaric
couple of spherical nuclei : different magnetic fields:
Neodymium(144,60)- Samarium(144,62) et al. body-body U+U collisions
Deformed nuclei can provide the collisions with zero magnetic field
and large v 2 to test the theory. CP-violating decays + - et al. R.
Millo and E. V. Shuryak, arXiv:0912.4894