Transcript ZDC Status 30 March 07 Michael Murray
Flavor Dynamics Michael Murray for BRAHMS
C. Arsene 12 , I. G. Bearden 7 , D. Beavis 1 , S. Bekele 12 , C. Besliu 10 , B. Budick 6 , H. B ø ggild 7 , C. Chasman 1 , C. H. Christensen 7 , P. Christiansen 7 , H.Dahlsgaard
7 , R. Debbe 1 , J. J. Gaardh ø je 7 , K. Hagel 8 , H. Ito 1 , A. Jipa 10 , E.B.Johnson
11, J ø rdre 9 , J. I.
,E. J. Kim
11 , T. C. E. J ø rgensen 7 , R. Karabowicz 5 , N. Katrynska 5 M. Larsen 7 , J. H. Lee 1 , Y. K. Lee 4 ,S. Lindahl 12 , G. L ø vh ø iden 12 , Z. Majka 5 , M. J. Murray 11 ,J. Natowitz 8 , C.Nygaard
7 B. S. Nielsen 7 , D. Ouerdane 7 , D.Pal
12 , F. Rami 3 , C. Ristea 8 , O. Ristea 11 , D. R ö hrich 9 , B. H. Samset 12 , S. J. Sanders 11 , R. A. Scheetz 1 , P. Staszel 5 , T. S. Tveter 12 , F. Videb æ k 1 , R. Wada 8 , H. Yang 9 , Z. Yin 9 , I. S. Zgura 2
Global Detectors
NYU, NBI, Kansas, Oslo
1
What are the dynamics of strange & light quarks?
• Baryon number is clearly transported in both rapidity and p T .
• Antibaryons and strange quarks are created • How do these different flavors interact • Can we learn something about the initial state of the system from their interaction. From apparatus => data => comparison to NLO QDC => inference concerning flow and limiting fragmentation => thermal descriptions versus rapidity => half finished wild speculation Michael Murray 2
B road Ra nge HA dronic M agnetic S pectrometers
Global Detectors Michael Murray 3
TIME-OF-FLIGHT
p max (2
cut) 0<
<1 (MRS) TOFW (GeV/c) TOFW2 (GeV/c)
Particle Identification
m 2 p 2 c 2 TOF 2 L 2 1
1.5<
<4 (FS) TOF1 (GeV/c) TOF2 (GeV/c) K/
K/p 2.0
3.5
2.5
4.0
3.0
5.5
4.5
7.5
RICH
Ring radius vs momentum gives PID / K separation 25 GeV/c Proton ID up to 35 GeV/c (2 settings) Michael Murray 4
Invariant yields over a broad range of phase space
Michael Murray 5
Finding
through weak decay to K + ,K -
Preliminary AuAu y~1 minimum bias, 200GeV N
= 120
35 Invariant mass of K + K -
Michael Murray
pair (GeV/c 2 )
6
Fitting m T spectra gives dN/dy and T
dN/dy = 2.09 T = 354
1.00
0.25
109
35 MeV Consistent with STAR at y=0
Michael Murray 7
pp =>
, k, p at 200GeV
=2p T
=1/2p T PRL 98, 252001 p T (GeV/c)
8
Baryon transport for pp at
s = 62GeV
Preliminary
Models such as Pythia seriously underestimate the yield of high p T protons at forward rapidities
dN dy
dN/dy =0.7 e y-yb => dN/dx=c Michael Murray
Preliminary Rapidity
9
Baryon Transport in AuAu For AuAu collisions a parton my be hit multiple times and the rapidity distribution flattens out
AGS SPS
(BRAHMS preliminary)
RHIC 62 RHIC 200 LHC 5500
Michael Murray 10
AuAu rapidity loss flattens out between SPS & RHIC
y = A -B e -ybeam ybeam
Peak of proton dN/dy should fall in acceptance of CASTOR at LHC Michael Murray 11
Limiting fragmentation pp =>
, k
y-ybeam
Michael Murray
y-ybeam
12
Limiting fragmenation even works for p, pbar
y-ybeam
Michael Murray 13
Limiting
Fragmentation
also works in AuAu
BRAHMS Preliminary + NA49 1 N part dN dy
Michael Murray
y - ybeam
14
Elliptic flow, v 2 (p T ) is independent of rapidity
Preliminary AuAu at √s NN = 200GeV, 0-50% central PRC72 014904
decreases with y 15 V 2 (p T ) scaling at central & forward rapidity Michael Murray 16 dN/dy Yields of produced particles are Gaussian Central 62GeV AuAu => , K pbar Preliminary rapidity Michael Murray 17 Are different regions of rapidity in chemical equilibrium? At each rapidity assume chemical equilibrium and strangeness neutrality N ( p ) e 6 B / T N ( p ) and N ( K ) N ( K ) e 2 ( B s ) / T K K p p 1 / 3 e 2 s / T Michael Murray 18 K /K + ratios seem to be controlled by pbar/p Chemical freeze-out BRAHMS PRELIMINARY Michael Murray 19 Does pbar/p control rapidity dependence strangeness in pp too? Note for pp we have to be careful to conserve quantum numbers in each event Not so good here Michael Murray 20 Fit ± , K ± , p and pbar dN/dy to a temperature and chemical potentials for strange & light quarks "THERMUS -- A Thermal Model Package for ROOT", S. Wheaton and J. Cleymans, hep-ph/0407174 T=116 9 MeV Assumption of strangeness neutrality could be checked by comparing to yields T=160 MeV T=148 3 MeV Michael Murray 21 Are protons black, white holes? Colour charges are confined If we change the gravitational force with the strong nuclear force then R ~ 1fm. Michael Murray 22 + - Black Holes and the uncertainty principle Michael Murray 23 + Black Holes radiate with T = 1/(8 GM) Michael Murray 24 + If black holes are charged the temperature changes Charge Michael Murray - 25 M => E Q => B G => 1/2 Michael Murray 26 First look for white holes in AuAu collisions STAR 200GeV AuAu Michael Murray 27 First look for white holes in AuAu collisions These points have comparable p-pbar Assuming white hole hypothesis works at 200GeV implies T=137 5 MeV for 63GeV, y=0 Michael Murray 28 • Do thermal analysis as a function of centrality • Use particle abundances and average momenta to estimate dE T /dy vs √S and centrality. • Test if “White Hole” hypothesis can explain BRAHMS data in terms of thermal distributions Michael Murray 29 • NLO pQCD has trouble describing p and pbar spectra for the forward region of pp collisions • A wide range of phenomena obey limiting fragmentation • Elliptic flow at a given p with √S and y T is independent of y • Particle yields at a given rapidity can be described within a thermal framework. The temperature falls • Somehow we need to explain very rapid, perhaps instant, thermalization of the system with parameters driven by the baryon density. We are investigating the charged “white hole” hypothesis. Michael Murray 30 Backups Michael Murray 31 Particle ratios vs rapidity Michael Murray 32 and radiation A stationary observer in the blue region sees the thermal radiation of temperature T = a/2 Mass m 1/a Pictures from Castorina, Kharzeev & Satz hep-ph/0704.1426 Michael Murray 33 For NA27, the K /K + ratio seems to be high NA49 could clarify this Michael Murray 34Search for charge white holes @ RHIC
Next Steps
Conclusions
Acceleration