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Production of light anti-nuclei, hyper-antinuclei, and their characteristics in high-energy nuclear collisions

Gang Chen, Huan Chen

China University of Geosciences, Wuhan

Collaborators Yu-Liang Yan, Ben-Hao Sa (CIAE, China) Dai-Mei zhou (CCNU, China)

China-Norway Physics Workshop III,Wuhan, China, May 10, 2014.

• Found hypernuclei

• Analysis Method

• The Results

• Summary

Outline

Found hypernuclei

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)(3

3

pnH

pnH

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from Hypernuclei to Neutron Stars

hypernuclei -B Interaction Neutron Stars

S=-1

S=-2

S=-0

Propose Propose Several possible configurations of Several possible configurations of Neutron StarsNeutron Stars– Kaon condensate,Kaon condensate, hyperons hyperons, strange quark matter, strange quark matter

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

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Tracks in TPC• It is first fonud nuclear contain anti-strange quark;• The chart of nuclides is expand to the new anti-strange matter r

egion.

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70±17 antihypertritons157 ±30 hypertritons

With About 89 million minimum-bias events and 22 million most central collisions events, from Au+Au collisions of √sNN=200 GeV

STAR, Science 328 (2010) 58

Measured invariant hypernuclei yields

(STAR) N AT U R E 4 7 3 (2 0 1 1)

N. Sharma ( ALICE) J.Phys.G 38 (2011);arXiv:1104.3311v2

Raw yield of anti-deuterons as a function transverse momentum

Production of antinuclei in pp collisions at 7 TeV with ALICE at the LHC

Found hypernuclei in the high energy collision exp.

So we try to proposed a dynamically constrained phase space coalescence model + PACIAE model and used to investigate the production of light nuclei (anti-nuclei) in high energy collisions .

The discovery for hypernuclei in the high energy experiment have been widely fascinating the sights of nuclear physicists.

Analysis Method

PACIAE model

1. The string fragmentation in PYTHIA is switched-off temporarily and the diquarks (anti-diquarks) are broken randomly into quarks (antiquarks), so the

parton initial state is obtained.

2. The parton rescattering is proceeded until partonic freez-out.

3. Then the hadronization is followed.

4. At last the hadronic rescattering is proceeded until hadronic freez-out.

Ben-Hao Sa ,etal. Comput. Phys. Commun., 183, 333 (2012).

It is the parton and hadron cascade Model based on PYTHIA.

Analysis MethodDynamically constrained phase space coalescence model

In the theoretical studies, the yield of light nuclei (anti-nuclei) is usually calculated in two steps: (1)The nucleons and hyperons are calculated by the transport model. (2)The light nuclei (anti-nuclei) are calculated by the phase space coalescence model with Wigner function or by the statistical model . This coalescence model strongly relies upon the assumption of light nuclei (anti-nuclei) wave function used to construct the Wigner function . The statistical model strongly relies upon the equilibrium assumption and the fitted temperature and baryon chemical potential.

We proposed a dynamically constrained phase space coalescence model to calculate the yield of light nuclei (anti-nuclei) after the transport model simulations.

Ben-Hao Sa ,etal. Comput. Phys. Commun., 183, 333 (2012).

Yu-Liang Yan, Gang Chen et al, Phys. Rev. C 85 024907 (2012).

As the uncertainty principle

one can only say particle lies somewhere within a six dimension quantum ``box" or “state" of volume of ΔqΔp

However,we can estimate the yield of a single particle by

Similarly for the yield of N particles cluster

Dynamically constrained phase space coalescence model

The yield of , for instance, is assumed to be

Dynamically constrained phase space coalescence model

H3

m0 stand for the rest mass of H3

Δm refers to the allowed uncertainty.

Where, the constraints

D0 stand for the Limiting the spatial position

The Results in p+p coll.

The model parameters are fitted to the STAR data of strange particles as shown in the following table.

TABLE I: Particle yield in NSD pp

collisions at = 0.2 TeV.

B. I. Abelev, et al., STAR , Phys. Rev. C 75 064901 (2007).

s

3

Then they are used to calculate the yield of D, 3He, and , etc.,

Yu-Liang Yan, Gang Chen et al, Phys. Rev. C 85 024907 (2012).

The Results of Hadron and light (anti)nuclei in p+p coll.

Tab I: Hadron and light nuclei (anti-nuclei) yields in NSD p+p collisions at √s=7 and 14 TeV calculated by final hadronic state in the PACIAE and PYTHIA simulations.

a Calculated with △m=0.0005 GeV.b Estimated from ALICE Data , J.Phys.G 38(2011)

c Calculated with △m=0.005 GeV.

predict the light (anti)nuclei yields in p+p collisions at √s = 7 and 14 TeV .


FIG. 1: Transverse momentum distributions of light anti-nuclei in the NSD pp collisions at = 7 and 14 TeV with PACIAE and PYTHIA model The green dots are ALICE data .

s

FIG. 2: Rapidity distributions of light anti-nuclei in the NSD pp collisions at =7 and 14 TeV with PACIAE and PYTHIA model


The strong fluctuation, indicates that the 1.2 x108 events are not enough for the pT and y distribution of the particles.

s

The Results in Au+Au coll. at √sNN =200 GeVChen Gang Yu-Liang Yan et al , PRC 86, 054910(2012)

The model parameters are fitted to the STAR data of strange particles as shown in the following table and Fig 1. Then they are used to calculate the yield of D, 3He, and , etc.,

STARa, PRL 98, 062301 (2007) A. Andronic et al., PLB 697, 203 (2011)

Tab 1 Hadron yields from Model in comparison with the STAR data

Obviously, the model results are very close to the data exp

H3

Fig 1 Hadron yields from Model in comparison with the STAR data

f Δm=0.0003 GeV. bΔm=0.00015 GeV.f Δm=0.0003 GeV. bΔm=0.00015 GeV.

Tab 2 Light (anti)nuclei yields of models in comparison with the STAR

The yields in PACIAE model simulation are consistent with STAR data.

egh The STAR, Science 328, 58 (2010);a L. Xue,Y. G. Ma et al.,PRC. 85 064912 (2012).c A. Andronic,et al., PLB 697(2011)

The Results in Au+Au coll. at =200 GeVs

Chen Gang et al , PRC 86, 054910(2012)

Fig 2 The comparison of particles ratios between data and model calculations.

The Results in Au+Au coll. at = 200 GeV

Δm=0.0003 GeV for D, Δm=0.00015 GeV for , , ,

Δm=0.0003 GeV for D, Δm=0.00015 GeV for , , , H3

D

He3 He3 H3

The STAR yield ratios are good reproduced.

Tab 3 Light (anti)nuclei ratio in comparison with the STAR data

s


Fig 3 Transverse momentum distributions of light (anti)nuclei .

The Results in Au+Au coll. at =200 GeVs


• Using PACIAE + the dynamically constrained phase space coalescence (DCPC) model to calculate the light nuclei (anti-nuclei) in high enengy collisions, it seams successful.

• It turned out that PACIAE + DCPC model would be an effective method investigating the production of light (anti)nuclei in high energy collisions.

The Centrality dependence of light anti-nuclear produced in Au+Au coll.


FIG. 1. The integrated yield dN/dy of strange particle at midrapidity Au+Au collisions at 200 GeV as a function of centrality.

The yields in PACIAE model simulation are consistent with STAR data.



TAB I: Integrated yields dN/dy calculated by PACIAE+DCPC model .

Δm=0.00035GeV for D, ; Δm=0.0002 GeV for , , , Δm=0.00035GeV for D, ; Δm=0.0002 GeV for , , , H3D He3He3 H3

The yields in the DCPC model decrease (or increase) with the increase of centrality (or Npart); the yields of antinuclei are less than those of its corresponding nuclei; and the greater the mass is, the lower the yield.


FIG. 2: The cumulative yields YC for light (anti)nuclei and (anti) hypertriton ， in midrapidity Au+Au collisions at √sNN = 200 GeV, plotted as a function of centrality.

STAR ,Science 328, 58 (2010)STAR ,arXiv:0909.0566PHENIX , PRL. 94 , 122302 (2005).

The yields in PACIAE + DCPC model simulation are consistent with Exp. data.


The cumulative yield Yc is defined as



FIG. 3: The normalized yield as a function of centrality bin ， calculated by PACIAE + DCPC model in the midrapidity Au+Au collisions at √sNN= 200 GeV,

Defined a normalized yield

The curves are fitted by

Theoretical and exp. results of yields in different centrality bins can be converted into the constant yield YMB for direct comparison.



FIG. 4 Yield ratios of light (anti) nuclei and (anti) ypertriton in mid -rapidity Au+Au collisions at √sNN = 200 GeV, plotted as a unction of centrality.

Their yield ratios also remain unchanged from central to peripheral coll.

Scaling Properties of light antinuclei production in Au+Au coll.

L. Xue,Y. G. Ma,PRC85, 064912 (2012)STAR , Nature 473,353 (2011);

Hecke, Sorge, Xu, PRL. 81, 5764 (1998).

Fig.1 Differential invariant yields of light (anti)nuclei as a function of baryon number, in Au+Au collisions at √sNN = 200 GeV

Fig 1 depicts a decreasing exponential trend of the invariant yields with the increased baryon number.

The differential invariant yield or light(anti)nuclei is described by the equation


Fig.2: Atomic number dependence of the integrated yield dN/dy of light (anti)nuclei in different centrality Au+Au collisions at √sNN = 200 GeV

149 ± 3MeV for 0-5%,142 ±4 MeV for MB,125 ±6 MeV for 40-60%

Chen Gang, arXiv:1401.6872, 2014

Fit the curves to get the temperature at hadronic freeze-out:

The yields in PACIAE + DCPC model simulation are consistent with Exp. data.


Chen Gang, arXiv:1401.6872, 2014

Fig 3: The integrated yield normalized to C=0-5%, as a function of centrality, in themidrapidity Au+Au collisions at √sNN =200 GeV.

The yields of light (anti)nuclei and (anti)hypertriton decrease with the increase of the centrality.

This distribution properties mainly depend on their mass number,i.e. the greater the mass number is, the faster the yield decreases.


Defined a ratio of yield per Npart

Fig 4: Relative invariant yields at midrapidity divided by Npart, as a function of Npart normalized to the peripheral collisions (40-60%).The results are calculated by PACIAE+DCPC model in Au+Au collisions at √sNN =200 GeV .

We were surprised to find that the datum for all dfferent (anti)nuclei and (anti)hypertriton approache to the same straight line.

Summary

• The PACIAE+DCPC were proposed, it would be an effective method investigating the production of light (anti)nuclei in relativity heavy ion collision

• Predict the light (anti)nuclei yield, transverse momentum and the rapidity distribution in pp collisions at √s = 7 and 14 TeV .

• Studyed centrality dependence of light anti-nuclear produced in Au+Au collisions.

• Discuss Scaling Properties of light antinuclei production in Au+Au coll.

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