Particle Spectra at AGS, SPS and RHIC

Dieter Röhrich Fysisk institutt, Universitetet i Bergen

• Similarities and differences• Rapidity distributions

– net protons

– produced particles

• Transverse mass spectra• Hydrodynamics

Proton rapidity distribution

• AGS energies – centrality dependence

B. Back et al., E917 Collaboration. Phys. Rev. Lett. 86 (2001) 1970

Proton rapidity distribution

• AGS energies, central collisions- energy dependence

B. Back et al., E917 Collaboration. Phys. Rev. Lett. 86 (2001) 1970

F. Videbæk, nucl-ex/0106017

Stopping

• Rapidity shift - energy dependence

Net proton rapidity distribution – centrality dependence

• SPS, 158 GeV/nucl., NA49

• RHIC, sNN= 130 GeV, STAR, BRAHMS

N. Xu, QM2001

Proton and antiproton rapidity

distributions

• SPS, 158 GeV/nucl., NA49

Antiproton/proton ratio –

rapidity distribution • SPS, 158 GeV/nucl., NA49

• RHIC, sNN= 130 GeV, BRAHMS

Antiproton/proton ratio – centrality dependence

• SPS, 158 GeV/nucl., NA49

• RHIC, sNN= 130 GeV, BRAHMS

Rapidity distributions• AGS, 10.8 AGeV

+ = -

K+ broader than K-

p

N. Herrmann, J. P. Wessels and T. Wienold, Ann. Rev. Nucl. Part. Sci. 49 (1999) 581, and references therein

Pion rapidity distribution

• Comparison + and -

– SPS, central Pb+Pb, 158 GeV/nucl. NA49

Same widths for + and -

Kaon rapidity distribution

• Comparison K+ and K-

– SPS, central Pb+Pb, 40 GeV/nucl. NA49

Different widths for K+ and K-

-rapidity distribution

+

• Comparison + and -

– SPS, central Pb+Pb, 158 GeV/nucl. NA49

-

Different widths for + and -

A. Billmeier, PhD thesis, 2001; R. Barton, J. Phys. G27 (2001) 367

Rapidity distributions• Suddenly hadronizing QGP-fireball

+ remaining internal longitudinal flow of colliding quarks

J. Letessier, J. Rafelski, hep-ph/0106151

= 1.22

K+ = 1.25

(K- = 1.17)

SPSNA49

Transverse momentum spectra

• Inv. CS

mmT

1/m

T d

N/d

mT

(a.u

.)

X.-N. Wang, QM01

Hard component:

next session

Soft component:

• Transverse mass spectra

fit function: 1/mTdN/dmT ~ exp(-mT/T)

fit range: : pT ~ .3 – 1 GeV/cheavier hadrons:

pT 1.5–2 GeV/c

Transverse mass spectra

Histograms: RQMD; fit: 1/mTdN/dmT ~ exp(-mT/T)

• Comparison K+ and K-

– SPS, NA44

Transverse mass spectra

• Central Pb+Pb collisions, inverse slopes: = 305 ± 25 MeV, = 287 ± 30 MeV;

• Similar spectra for particle/antiparticle

• Comparison + and -

– SPS, Pb+Pb, 158 GeV/nucl., different centralities

WA97

Transverse mass spectra

• Identical slope parameters

• Indication of deviations from single slope fit at low and high mT

• Comparison and RHIC, central Au+Au (14%)

STAR

e(-mt/T)

x

T=352+-7 MeV

No feed-down correction

Centrality dependence of transverse mass spectra (1)

• SPS,

158 GeV/nucl.,

WA97:

• RHIC,

STAR:

-+

No dependence

No dependence

STAR, submitted to Phys. Rev. Lett

Centrality dependence of transverse mass spectra (2)

• RHIC, Au+Au

STAR: -

• RHIC, Au+Au

STAR: p

Slight dependence

Strong dependence

J.W. Harris, QM01

J.W. Harris, QM01

Inverse slope parameter –p+p vs Pb+Pb

• SPS,

p+p

• SPS,

central

Pb+Pb

NA49;A.M. Rossi, Nucl. Phys. B84 (1975) 269

Inverse slope parameter vs particle mass (1)

• RHIC, central Au+Au

K p

STAR data: C. Roy, this conference

Inverse slope parameter vs particle mass (2)

• Comparison RHIC (central Au+Au) and SPS (central Pb+Pb)

K p d J/

STAR data: C. Roy, this conference

Inverse slope parameter vs sqrt(s)

• -+

NA49, STAR

Central Au+Au(Pb+Pb)

p+p

Nucl.Phys. A661(1999)506

Phys.Rev.Lett B491(2000)59

Nucl.Phys. B203(1982)27

Sudden breakup of QGP-fireball• Thermal freeze-out conditions

= chemical freeze-out

SPS, central Pb+Pb, WA97 data J. Rafelski, G. Torrieri, J. Letessier,

hep-ph/0104132

Tfo,global 145 MeVv 0.52c

Hydrodynamics motivated mT fit (1)

• SPS, central Pb+Pb; H. Appelshaeuser (NA49), Eur. Phys. J. C2 (1998)

661; B. Tomasik, U. Wiedemann, U.W. Heinz, nucl th/9907096

Tfo 100 MeV<v> 0.55c

• Correlate - transverse mass spectrum and -- Bose-Einstein correlations

2 contour plots for the fits of the single particle mT-spectrum and of the Cartesian HBT radii

Hydrodynamics motivated mT fit (2)

• RHIC, central Au+Au; STAR

S. Margetis, ThermalFest, 2001; P. Jones, this conference

tanh 1 r

r (r) s f (r)

R

s

E.Schnedermann et al, PRC48 (1993) 2462

flow profile used:

r =s (r/R)0.5

dn

mT dmT r dr mT K1

mT coshT

0

R

I0pT sinh

T

Shape of the mT spectrum depends on particle mass, mT-range, flow profile:

where

and

mT - m0 [GeV/c2]

1/m

T d

N/d

mT

(a.

u.)

STAR Preliminary

-

K-

p

solid : used in fit

Hydrodynamics motivated mT fit (3)

• RHIC, central Au+Au; STAR

S. Margetis, ThermalFest, 2001; P. Jones, this conference

K-p

-

<r > [c]

Tth [

GeV

]

At chi square minimum

Tth = 0.13 [GeV]

<r > = 0.52 [c]

0 0.4

Strong radial flow at RHICßr (RHIC) = 0.52c

Tfo (RHIC) = 0.13 GeV

2 map (contour plot for 95.5%CL)

0 0.4

Hydrodynamics motivated mT fit (4)

• RHIC, central Au+Au, -K-p; PHENIX

J. Buward-Hoy, ThermalFest, 2001

1/mt dN/dmt = A f() d mT K1( mT /Tfo cosh ) I0( pT /Tfo sinh )

linear velocity profile:

where radius r = r/R, particle density distribution:

t()

1

f()

PHENIX Preliminary

Tfo ~ 125 - 83 MeV ~ 104 MeV t ~ 0.6 - 0.8 ~ 0.7

< t> ~ 0.4 - 0.6 ~ 0.5

Hydro + Cascade model

• SPS, RHIC, central Pb+Pb (Au+Au)D. Teaney, J. Lauret, E.V. Shuryak,

nucl-th/0104041

• RHIC, central Au+Au; PHENIX

J. Buward-Hoy, ThermalFest, 2001 , K

• Tfo ~ 135 MeV

• <t > ~ 0.55

• nucleons

• Tfo ~ 120 MeV

• <t > ~ 0.6

Summary

• Variety of shapes of rapidity distributions

• Complex transverse mass spectra

• Hydrodynamics– Strong radial flow

t 0.5-0.7c

– Sudden QGP break up model:• Tglobal 145 MeV (SPS)

– Hydro mT-fits:

• Tfo, thermal 100-130 MeV