suk choi , kang seog lee chonnam national university
DESCRIPTION
Two freeze-out model for the hadrons produced in the Relativistic Heavy-Ion Collisions. New Frontiers in QCD 28 Oct, 2011, Yonsei Univ., Seoul, Korea. Suk Choi , Kang Seog Lee Chonnam National University. What can we know from particle spectra?. Hadron yield : - PowerPoint PPT PresentationTRANSCRIPT
Two freeze-out modelfor the hadrons produced in the Relativistic Heavy-Ion Collisions.
New Frontiers in QCD 28 Oct, 2011, Yonsei Univ., Seoul, Korea
Suk Choi , Kang Seog Lee
Chonnam National University
What can we know from particle spectra?
Hadron yield : chemical freeze-out temperature
baryon and strange chemical potential strange saturation factor
Pt-spectra : thermal freeze-out temperature
chemical potentials(baryon, strange,…)system size, transverse expansion velocity
1.Chemical analysis Multiplicities or ratios of hadrons
are nicely fitted with statistical distributions.
parameters : Tch , B,ch , s,ch , s
= Tch at RHIC energy is close to the phase transition temperature to
QGP.
= The hadrons are chemically frozen out just after the
hadronization.
= s close to 1, and the strangeness is nearly equilibrated.
chi Te /)(
Analysis 1.
2. Thermal analysis
The slopes of pt spectra are well explained with expanding
fireball model when absolute magnitude for each hadrons is
arbitrary adjusted .
parameters : Tth , B,th , s,th ,
= The success of thermal analysis (pt < 2GeV/c) is the evidence of
the radial expansion.
thi Tupe /)(
Analysis 2.
J. Adams et al. [STAR Collaboration] 2004, Phys. Rev. Lett. 92 112301
1. The temperatures of the two analysis are different, Tch Tth.
2. The magnitudes and slopes of transverse momentum spectra of various hadrons cannot be fitted simultaneously.
?
Chemical freeze-out occurs earlier at high temperature than thermal freeze-out.
The inelastic collisions becomes less frequent. The numbers of each hadron species are no more changing thus
kept fixed. The system expand continuing with elastic collisions.
U. Heinz, AIP conf. Proc. 602:281-292, 2001
Cooper-Frye Formula
H. Dobler, J. Sollfrank, U. Heinz, P. L. B457,353(1999)J. D. Bjorken, Phys. Rev. D Vol. 27, 1F. Cooper and G. Frye, Phys. Rev. D 10, 140(1974)
For an ellipsoidally expanding fireball
Blast-wave model
Hadron yields, slopes and magnitude of mt spectra of various hadrons can be simultaneously explained within a single model.
Consistent way of analyzing both the ratios and pt spectrum
Nith is fixed.
Calculate chemical potential of each particles mi from Ni
th.
Thermal freeze-out Find thermal freeze out parameters to fit mt spectra using i.Resonance contribution should be included.
Tch Tth
Chemical freeze out: Number of each particles is fixed.
Chemical analysis
Total Particle Number
Chemical Potential
T>Tch : The hot and dense system is chemically
equilibrated.
T<Tch : All kind of hadrons are frozen out
and the number of hadrons are fixed.
Transverse Mass Spectrum
Chemical Potential from particle ratios fixed at Tch.
Thermal analysis
Hadron ratios at chemical freeze-out time
Strength of two freeze-out model
1.Two freeze-out model causes a small errors but reduces the computation significantly since the coupled equations for the chemical potentials now reduces to independent equations.
2.Two freeze-out model can explain ratios of hadrons , transverse momentum spectrum of each hadrons without arbitrary normalizations and rapidity distribution of charged hadrons.
Results of chemical analysis
Tch=173.4 MeV
B=18.5 MeV
s=7.9 MeV
s=0.986
2/n=1.4
Tch=173.9 MeV
B=26.4 MeV
s=6.0 MeV
s=1.01
2/n=0.12
Result of thermal analysis
Tth=121.1 MeV
=126.4 MeV
max=5.0
0=1.03
s=0.986
2/n=5.3
Result of rapidity distribution
Tth=121.1 MeV
=126.4 MeV
max=5.0
0=1.03
s=0.986
Conclusion
1. In an cylindrically expanding fireball model, both the hadron ratios, magnitude and slopes of the pt spectra at RHIC are described assuming two freeze-outs.2. Particle pt and rapidity spectra are nicely fitted without arbitrary normalization.3. We are eagerly waiting for LHC data to analyze.
I’ll give you chance which you can give me the LHC data(rapidity, Pt, ratios of particles).
Contact to me : [email protected]
Thanks ! ^.*
Reference[1] K. S. Lee, U. Heintz, E. Schnedermann : Z. Phys. C - Particles and Fields 48(1990)525-541[2] K. S. Lee, U. Heintz, Z. Phys. C43 (1989) 425-429[3] H. Dobler, J. Sollfrank, U. Heintz , [nucl-th/9904018][4] B. Pin-zhen, J Rafalski , [nucl-th/0507037][5] J. D. Bjorken, Physical Review D Vol. 27, Num. 1, January(1983)140-151[6] J. Sollfrank, P. Koch, U. Heintz, Z. Phys. Rev. Lett. 78. 2080(1997)[7] L. Landau, Izv. Akg. Nauk SSSR, 17, 51 (1953).[8] F. Cooper and G. Frye, Phys. Rev. D 10, 140(1974)[9] U. Heinz, AIP Conf. Proc. 602, 281 (2001), [hep-ph/0109006][10] J. Adams et al. (STAR), Phys. Rev. Lett. 92 (2004) 112301[nucl-ex/0310004].[11] J. Adams et al. (STAR), Phys. Lett. B 612 (2005) 181[nucl-ex/0406003].[12] J. Adams et al. (STAR), Phys. Rev. C 71 (2005) 064902 [nucl-ex/0412019].[13] A. Billmeier et al. (STAR), J. Phys. G 30 (2004) S363.[14] H. Zhang (STAR) [nucl-ex/0403010].[15] O. Barannikova (STAR) [nucl-ex/0403014].[16] Quark Gluon Plasma[17] STAR collaboration, Nucl. Phys. A757 : 102-183 (2005)[18] J. L. Klay et al.[E-0895] Collaboration], Phys. Rev. C 68, 054905(2003) [nucl-ex/0306033]