Search for the QCD critical point in ultrarelativistic ion collisions

Quark matter theory group, Department of Physics,

University of Athens

Members of the group: N.G. Antoniou, F.K. Diakonos, A.I. Karanikas, C.N. Ktorides, X.N. Maintas (staff) Y.F. Contoyiannis, A.S. Kapoyannis, G. Mavromanolakis, E. Saridakis (postdocs) N. Davis (PhD student), G. Tsolias (Msc student)

NRC Demokritos, October 2010, NUPECC

The QCD phase diagram ( a simplified version)

From R. Casalbuoni, POS CPOD2006:001 (2006); hep-ph/0610179

critical point

Why it is important?

Chiral condensation 99% of the mass of the

visible world

(consituent quark mass)

Thermodynamic properties of the QCD vacuum

Hadronization

B.L.Ioffe, Physics Uspekhi 49, 1077 (2006)

F. Wilczek, hep-ph/0003183

Characteristics of the critical point

• Order parameters

• Universality class: 3-D Ising

• Effective action at T=Tc (3 –D Ising)

0( ) ( ) ( ) ; ( ) ( ) ( )Bx q x q x n x q x q x

critical exponents: 5 ; 0 M. Stephanov, K. Rajagopal, E. Shuryak, Phys. Rev. Lett. 81, 4816 (1998)

M.M. Tsypin, Phys. Rev. Lett. 73, 2015 (1994); J. Berges, N. Tetradis, C. Wetterich, Phys. Rev. Lett.77, 873 (1996)

isoscalar sigma field net baryon density

Towards a critical point phenomenology

Critical QCDEffective action adapted for describing the critical state produced

in ultrarelativistic ion collisions (geometry and space time evolution)

Thermodynamics of the critical effective action-local fluctuations(dominant instanton-like configurations, clusters with fractal geometry (DF))

Power-law density-density correlations (intermittency in factorial moments (F2 ~ MD-DF) critical opalescence)

Critical Monte Carlo (CMC)

Publications

N.G. Antoniou, F.K. Diakonos, C.N. Ktorides and M. Lahanas :Critical events and Intermittency in nuclear collisions, Phys. Lett. B 432, 8 (1998)

N.G. Antoniou, Y.F. Contoyiannis, F.K. Diakonos and C.G. Papadopoulos :Fractals at T=Tc due to instantonlike configurations, Phys. Rev. Lett. 81, 4289 (1998)

N.G. Antoniou, Y.F. Contoyiannis and F.K. Diakonos :The fractal geometry of critical systems, Phys. Rev. E 62, 3125 (2000)

N.G. Antoniou, Y.F. Contoyiannis, F.K. Diakonos, A.I. Karanikas and C.N. Ktorides :Pion production from a critical QCD phase, Nucl. Phys. A 693, 799 (2001)

N.G. Antoniou, Y.F. Contoyiannis, F.K. Diakonos and G. Mavromanolakis : Critical QCD in nuclear collisions, Nucl. Phys. A 761, 149 (2005)

N.G. Antoniou, F.K. Diakonos, A.S. Kapoyannis and K.S. Kousouris:Critical opalescence in baryonic QCD matter, Phys. Rev. Lett. 97, 032002 (2006)

The critical point in experiments with colliding nuclei

Analysis scheme for the detection of the critical point in real data based on observation of local fluctuations (guide: CMC)

Intermittency in transverse momentum space (F2(M)~ M2φ2) of:(a) dipions (π+π-) close to the production threshold

(b) net baryons at midrapidity

Predictions of the intermittency exponents based on CQCD:

φ2 (dipions) =2/3 ; φ2(net baryons)=5/6

(verified through CMC events)

Application to NA49 A+A data (CERN-SPS) (A=p,C,Si,Pb)

(first indication of critical fluctuations in Si+Si)

100 1000 100001E-3

0.01

0.1

1

10

F2(

M)

Protons, Si+Si at 158 AGeV

M2

data mixed events F

2(M)

power-law fit to F2(M), slope=0.60(02)

10000

10

Dipions, Si+Si at 158 AGeV

dipions mixed events F

2(M)

power-law fit to F2, slope=0.30(06)

F2(

M)

M2

0 50 100 150 200 250 300 350

0.0

0.2

0.4

0.6

0.8

1.0

Pb, 0-5%Pb, 5-12%

Si

Si

C

critical QCD - dipions

critical QCD - net baryons

2

Nw

Freeze-out states of existing experimental data Indication of divergent baryon number susceptibility

isothermals

N.G. Antoniou, F.K. Diakonos and A.S. Kapoyannis:

The critical endpoint of bootstrap and lattice QCD matter, Nucl. Phys. A 759, 417 (2005)

N.G. Antoniou, F.K. Diakonos and E.N. Saridakis: Evolution of critical correlations at the QCD phase transition, Nucl. Phys. A 784, 536 (2007)

N.G. Antoniou, F.K. Diakonos and E.N. Saridakis: Evolutionary intermittency signaling the universality class of the QCD critical point, Phys. Rev. C 78, 024908 (2008)

N.G. Antoniou, F.K. Diakonos and A.S. Kapoyannis: Indication for divergent baryon-number susceptibility in QCD matter, Phys. Rev. C 81, 011901 (2010)

N.G. Antoniou, F.K. Diakonos, G. Mavromanolakis and the NA49 Collaboration:

Search for the QCD critical point in nuclear collisions at the CERN SPS,

Phys. Rev. C 81, 064907 (2010)

Publications

Future Plans

• Scan both the baryonic and the isocalar sector in peripheral Pb+Pb collisions using NA49 data

• Study the baryonic sector in C+C

• Apply the same analysis in the forthcoming NA61/SHINE data

THEORETICAL NUCLEAR PHYSICS

•Research program in the Department of Physics of the University of Athens since 1980

•Researchers:•E. Mavrommatis, F. Diakonos (permanent staff)

•Collaborators at intervals (2000-2010):•M. Petraki, P. Papakonstantinou, P. Papachristou•S. Athanassopoulos, N. Costiris, G. Pavlou, A. Dakos

•V. Constantoudis ( Demokritos), T. Kosmas (University of Ioannina)•C.C. Moustakidis (University of Thessaloniki), I. Lagaris (University of Ioannina)

•J.W. Clark (Washington Univ., USA), J. Wambach, V.Yu Ponomarev (T.U., Darmstadt, Germany), O. Benhar (La Sapienza Univ., Italy), S. Fantoni (SISSA, Italy), •A. Fabrocini† (Pisa Univ., Italy), K.A. Gernoth (UMIST, UK), A Shebeko (Kharkov •Inst., Ukraine) H. Li (Darmoth C., USA)

--- THEORETICAL NUCLEAR ASTROPHYSICS--- THEORY OF MANY BODY SYSTEMS--- THEORY OF COMPLEX SYSTEMS--- ARTIFICIAL INTELLIGENCE

Α. MICROSCOPIC THEORY OF MULTINUCLEON SYSTEMS

Study of correlations (short – range, long – range, pairing, complexity – chaos)

THEORETICAL NUCLEAR PHYSICS

Recent work:

“Non linear classical model for the decay widths of isoscalar giant monopole resonances”P.K. Papachristou, E. Mavrommatis, V.Constantoudis,, F.K. Diakonos, J. Wambach, Phys. Rev.C77 (2008)

044305

“A CBF study of 1 0 superfluidity in dilute neutron matter”

G. Pavlou, E. Mavrommatis, C.C.Moustakidis, J.W. Clark, in submission

B.STATISTICAL MODELING OF NUCLEAR PROPERTIES WITH METHODSFROM STATISTICAL ANALYSIS

Program: Pythagoras – Artificial Intelligence ModelingSite: www.pythaim.uoa.gr

Recent work:

“Nuclear mass systematics by complementing the finite range droplet model with neural networks”S. Athanassopoulos, E. Mavrommatis, K.A. Gernoth, J.W. Clark,in submission

“Decoding β-decay systematics: A global statistical model for β– half -lives ”N.J. Costiris, E. Mavrommatis, K.A. Gernoth, J.W. Clark, Phys. Rev.C80 (2009) 044332