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.
Outline
• Found hypernuclei
• Analysis Method
• The Results
• Summary
Found hypernuclei
3

H (n  p   )
3

H (n  p   )
from Hypernuclei to Neutron Stars
hypernuclei
-B Interaction
Neutron Stars
S=-2
S=-1
S=0
Saito, HYP06
J.M. Lattimer and M. Prakash,
Propose Several possible configurations of Neutron Stars"The Physics
of Neutron Stars", Science
– Kaon condensate, hyperons, strange quark matter
304, 536 (2004)
J. Schaffner and I. Mishustin, Phys. Rev. C
53 (1996):
Hyperon-rich matter in neutron stars
Tracks in TPC
• It is first fonud nuclear contain anti-strange quark;
• The chart of nuclides is expand to the new anti-strange matter
region.
5
Measured invariant hypernuclei yields
STAR, Science 328 (2010) 58
70±17 antihypertritons
157 ±30 hypertritons
6
With About 89 million minimum-bias events
and 22 million most central collisions events,
from Au+Au collisions of √sNN=200 GeV
(STAR) N AT U R E 4 7 3 (2 0 1 1)
Found hypernuclei in the high energy collision exp.
Production of antinuclei in pp collisions at 7 TeV with
ALICE at the LHC
Raw yield of anti-deuterons
as a function transverse
momentum
N. Sharma ( ALICE) J.Phys.G 38 (2011);arXiv:1104.3311v2
The discovery for hypernuclei in the high energy
experiment have been widely fascinating the sights
of nuclear physicists.
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 .
Analysis Method
PACIAE model
It is the parton and hadron cascade Model based on PYTHIA.
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).
Analysis Method
Dynamically 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).
Dynamically constrained phase space coalescence model
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 3
H
, for instance, is assumed to be
Where, the constraints
m0 stand for the rest mass of 3H
D0 stand for the Limiting the spatial position
Δm refers to the allowed uncertainty.
The Results in p+p coll.
Yu-Liang Yan, Gang Chen et al, Phys. Rev. C 85 024907 (2012).
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 s = 0.2 TeV.
B. I. Abelev, et al., STAR , Phys. Rev. C 75 064901 (2007).
Then they are used to calculate the yield of D,
3He,
and
3


, etc.,
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 .
The Results in p+p coll.
FIG. 1: Transverse momentum distributions of light anti-nuclei in the
NSD pp collisions at s= 7 and 14 TeV with PACIAE and PYTHIA model
The green dots are ALICE data .
The Results in p+p coll.
The strong fluctuation,
indicates that the
1.2 x108 events are not
enough for the pT and y
distribution of the
particles.
FIG. 2: Rapidity distributions of light anti-nuclei in the NSD pp
collisions at s =7 and 14 TeV with PACIAE and PYTHIA model
The Results in Au+Au coll. at √sNN =200 GeV
Chen 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
3
3
used to calculate the yield of D, He, and  H , etc.,
Tab 1 Hadron yields from Model in
comparison with the STAR data
STARa, PRL 98, 062301 (2007)
A. Andronic et al., PLB 697, 203 (2011)
Obviously, the model results are
very close to the data exp
Fig 1 Hadron yields from Model in
comparison with the STAR data
The Results in Au+Au coll. at
s =200
GeV
Tab 2 Light (anti)nuclei yields of models in comparison with the STAR
f
Δm=0.0003 GeV. bΔm=0.00015 GeV.
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)
Chen Gang et al , PRC 86, 054910(2012)
The yields in PACIAE
model simulation are
consistent with STAR
data.
The Results in Au+Au coll. at s = 200 GeV
Fig 2 The comparison of particles ratios
between data and model calculations.
Chen Gang et al , PRC 86, 054910(2012
Tab 3 Light (anti)nuclei ratio in
comparison with the STAR data
Δm=0.0003 GeV for D, D
Δm=0.00015 GeV for 3He , 3He , 3H , 3H
The STAR yield ratios are good
reproduced.
The Results in Au+Au coll. at s =200 GeV
Fig 3 Transverse momentum distributions of light (anti)nuclei .
Chen Gang et al , PRC 86, 054910(2012)
•
Using PACIAE + the dynamically constrained phase space
coalescence (DCPC) model to calculate the light nuclei (antinuclei) 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.
Chen Gang et al , PRC 88, 034908(2013)
The yields in PACIAE
model simulation are
consistent with STAR
data.
FIG. 1. The integrated yield dN/dy of strange particle at midrapidity
Au+Au collisions at 200 GeV as a function of centrality.
The Centrality dependence of light
anti-nuclear produced in Au+Au coll.
Chen Gang et al , PRC 88, 034908(2013)
TAB I: Integrated yields dN/dy calculated by PACIAE+DCPC model .
Δm=0.00035GeV for D, D ; Δm=0.0002 GeV for 3He ,3He , 3H ,
3

H
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.
The Centrality dependence of light antinuclear produced in Au+Au coll.
Chen Gang et al , PRC 88, 034908(2013)
The cumulative yield Yc is
defined as
STAR ,Science 328, 58 (2010)
STAR ,arXiv:0909.0566
PHENIX , PRL. 94 , 122302 (2005).
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.
The yields in PACIAE + DCPC
model
simulation
are
consistent with Exp. data.
The Centrality dependence of light anti-nuclear
produced in Au+Au coll.
Chen Gang et al , PRC 88, 034908(2013)
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. 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,
The Centrality dependence of light antinuclear produced in Au+Au coll.
Chen Gang et al , PRC 88, 034908(2013)
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.
The differential invariant yield or light
(anti)nuclei is described by the equation
Fig 1 depicts a decreasing exponential
trend of the invariant yields with the
increased baryon number.
Fig.1 Differential invariant yields of
light (anti)nuclei as a function of
baryon number, in Au+Au collisions at
√sNN = 200 GeV
Hecke, Sorge, Xu, PRL. 81, 5764 (1998).
STAR , Nature 473,353 (2011);
L. Xue,Y. G. Ma,PRC85, 064912 (2012)
Scaling Properties of light antinuclei
production in Au+Au coll.
Chen Gang, arXiv:1401.6872, 2014
The yields in PACIAE + DCPC
model
simulation
are
consistent with Exp. data.
Fit the curves to get
the temperature at
hadronic freeze-out:
149 ± 3MeV for 0-5%,
142 ±4 MeV for MB,
125 ±6 MeV for 40-60%
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
Scaling Properties of light antinuclei
production in Au+Au coll.
Chen Gang, arXiv:1401.6872, 2014
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.
Fig 3: The integrated yield normalized to
C=0-5%, as a function of centrality, in the
midrapidity Au+Au collisions at √sNN =200 GeV.
Scaling Properties of light antinuclei
production in Au+Au coll.
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.
Thanks for your
attention!
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