Michael Murray 1

GlobalDetectors

Flavor DynamicsMichael Murray for BRAHMS

C. Arsene12, I. G. Bearden7, D. Beavis1, S. Bekele12, C. Besliu10, B. Budick6,

H. Bøggild7, C. Chasman1, C. H. Christensen7, P. Christiansen7, H.Dahlsgaard7, R. Debbe1,

J. J. Gaardhøje7, K. Hagel8, H. Ito1, A. Jipa10, E.B.Johnson11, J. I. Jørdre9,

C. E. Jørgensen7, R. Karabowicz5, N. Katrynska5 ,E. J. Kim11, T. M. Larsen7, J. H. Lee1,

Y. K. Lee4,S. Lindahl12, G. Løvhøiden12, Z. Majka5, M. J. Murray11,J. Natowitz8, C.Nygaard7

B. S. Nielsen7, D. Ouerdane7, D.Pal12, F. Rami3, C. Ristea8, O. Ristea11,

D. Röhrich9, B. H. Samset12, S. J. Sanders11, R. A. Scheetz1, P. Staszel5,

T. S. Tveter12, F. Videbæk1, R. Wada8, H. Yang9, Z. Yin9, I. S. Zgura2

BNL, Bucharest, Strasbourg, John Hopkins, Krakow, NYU, NBI, Kansas, Oslo

Michael Murray 2

What are the dynamics of strange & light quarks?

• Baryon number is clearly transported in both rapidity and pT.

• 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 3

GlobalDetectors

Broad Range HAdronic Magnetic Spectrometers

Michael Murray 4

1

L

TOFcpm

2

2222TIME-OF-FLIGHT

0<<1(MRS)

1.5<<4(FS)

pmax

(2 cut)

TOFW (GeV/c)

TOFW2 (GeV/c)

TOF1 (GeV/c)

TOF2 (GeV/c)

K/ 2.0 2.5 3.0 4.5

K/p 3.5 4.0 5.5 7.5

Ring radius vs momentum gives PID / K separation 25 GeV/cProton ID up to 35 GeV/c

(2 settings)

RICH

Particle Identification

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Invariant yields over a broad range of phase space

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N = 12035

Finding through

weak decay to K+,K-

Invariant mass of K+K- pair (GeV/c2)

Preliminary AuAu y~1 minimum bias, 200GeV

Michael Murray 7

dN/dy = 2.09 1.00 0.25T = 354 109 35 MeV

Consistent with STAR at y=0

Fitting mT spectra gives dN/dy and T

Michael Murray 8

pp => , k, p at 200GeV

pT (GeV/c)

PRL 98, 252001=2pT

=1/2pT

Michael Murray 9

Baryon transport for pp at s = 62GeV

dN/dy =0.7 ey-yb => dN/dx=c

Rapidity

dNdy

Models such as Pythia seriously underestimate the yield of high pT protons at forward rapidities

Preliminary

Preliminary

Michael Murray 10

Baryon Transport in AuAu

“net”

pro

ton

AGS

SPS

RHIC 62

RHIC 200

LHC 5500

dN

/dy

(BRAHMS preliminary)

For AuAu collisions a parton my be hit multiple times and the rapidity distribution flattens out

Michael Murray 11

y = A -B e-ybeam

AuAu rapidity loss flattens out between SPS & RHIC

ybeam

Peak of proton dN/dy should fall in acceptance of CASTOR at LHC

Michael Murray 12

Limiting fragmentation pp => , k

y-ybeam

y-ybeam

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Limiting fragmenation even works for p, pbar

y-ybeam

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Limiting Fragmentation also works in AuAu

BRAHMS Preliminary + NA49

dNdy

1Npart

y - ybeam

Michael Murray 15

PRC72 014904

Preliminary AuAu at √sNN = 200GeV, 0-50% central

Elliptic flow, v2(pT) is independent of rapidity

<V2> decreases with y because <pT> decreases with y

Michael Murray 16

V2(pT) scaling at central & forward rapidity

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Yields of produced particles are Gaussian

Central 62GeV AuAu => , K pbar

Preliminary

rapidity

dN/dy

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TBepN

pN /6

)(

)(

At each rapidity assume chemical equilibrium and strangeness neutrality

and

TsBeKN

KN /)(2

)(

)(

Tsep

p

K

K /2

3/1

Are different regions of rapidity in chemical equilibrium?

Michael Murray 19

BRAHMS PRELIMINARY

K-/K+ ratios seem to be controlled by pbar/p

Michael Murray 20

Does pbar/p control rapidity

dependence strangeness in

pp too?

Not so good here

Note for pp we have to be careful to conserve quantum numbers in each event

Michael Murray 21

Fit ±, K±, p and pbar dN/dy to a temperature and chemical potentials for strange & light quarks

T=1169 MeV

T=1483 MeVT=160 MeV

"THERMUS -- A Thermal Model Package for ROOT", S. Wheaton and J. Cleymans, hep-ph/0407174

Assumption of strangeness neutrality could be checked by comparing to yields

Michael Murray 22

Are protons black, white holes?Colour charges are confined

If we change the gravitational force with the strong nuclear force then R ~ 1fm.

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Black Holes and the uncertainty principle

+

-

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Black Holes radiate with T = 1/(8GM)

+

Michael Murray 25

If black holes are charged the temperature changes

+

-

-

-

-

--

-

-

Tem

pera

ture

Charge

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Slide 3

Search for charge white holes @ RHIC

M => E

Q => B

G => 1/2

Michael Murray 27

First look for white holes in AuAu collisions

STAR 200GeV AuAu

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First look for white holes in AuAu collisions

These points have comparable p-pbar

Assuming white hole hypothesis works at 200GeV implies T=1375 MeV for 63GeV, y=0

Michael Murray 29

Next Steps

• Do thermal analysis as a function of centrality

• Use particle abundances and average momenta to estimate dET/dy vs √S and centrality.

• Test if “White Hole” hypothesis can explain BRAHMS data in terms of thermal distributions

Michael Murray 30

Conclusions

• 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 pT is independent of y

• Particle yields at a given rapidity can be described within a thermal framework. The temperature falls with √S and y

• 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.

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Backups

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Particle ratios vs rapidity

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Acceleration and radiation

A stationary observer in the blue region sees the thermal radiation of temperature T = a/2

Pictures from Castorina, Kharzeev & Satz hep-ph/0704.1426

Mass m

1/a

Michael Murray 34

For NA27, the K-/K+ ratio seems to be high

NA49 could clarify this