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Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 11Zakopane, June 06, HBZakopane, June 06, HB
Wounded Nucleons,Wounded Nucleons,Wounded Quarks,Wounded Quarks,and Relativistic Ion and Relativistic Ion
CollisionsCollisionsHelena BiałkowskaHelena Białkowska
Institute for Nuclear StudiesInstitute for Nuclear Studies
WarsawWarsaw
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 22
What is a wounded nucleon?What is a wounded nucleon?• Classic definition,
given by Białas, Błeszyński & Czyż in 1976:
It is a nucleon that underwent at least one inelastic collision
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 33
The WNM (1976!) – as usual – The WNM (1976!) – as usual – started from experimental started from experimental
observation:observation:• Series of Fermilab expt`s
on h-A• also European NA5• and lots of emulsion data• Average multiplicity and
increases more slowly than the number of collisions
ddn /
hAhpA /
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 44
21 hphAA nnR /
And this is just the ratio of participants in p-A(1 from p and from nucleus A) and in p-p (2 protons)
Observation: ratio of multiplicities (hA/hp) behaves as
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 55
The Model:The Model:
Particle production in a nuclear collision -a superposition of independent contributionsfrom the wounded nucleons in the projectileand the target
Thus you can:1 just measure NN2 count the participants in h - A3 and you have particle multiplicity in h – A!
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 66
For p-A:works surprisingly well.from AGS energiesup to RHIC!
Notice:we check here both Npart scalingand pp scaling
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 77
New idea: not wounded New idea: not wounded nucleons but wounded quarksnucleons but wounded quarks
Andrzej Białas et al., 1977, Vladimir Anisovitch et al., 1978
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 88
Additive Quark ModelAdditive Quark Model
1982 Białas et al.:Specific predictions for nuclear collisions on the basis ofthe Additive Quark Model - with particle production fromthree sources:Breaking of the color strings between quarks fromthe projectile and the targetFragmentation of wounded quarks Fragmentation of spectator quarks
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 99
Thus for central region
Ratio of multiplicities in A-B to that in pp given by
ABqq
qBqABAR
),(
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1010
Pre-history: 1980Pre-history: 1980
2.06.3 dTa
CTa
P,d,,C on Ta, 4.2 GeV/NJINR DUBNA
Model: 3.0
1.07.1 dTa
Ta Model 1.6
AQM
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1111
First real high energy nuclear beams:200 GeV/c O and S from SPSK. Kadija et al., ZPhysC66,393(1995) consistent parametrization of production rates of negatives – proportional to the No of wounded nucleonsand of kaons – proportional to wounded quarks
More history: NA35
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1212
WNAB works
for negatives
… and it does not for K0s
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1313
For kaons - need Wq
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1414
Now for RHIC A – A data:
Notice: AuAuscaled by ppat twice the energy!
s2
(to account for ‘leading baryon’)
PHOBOSWhite Paper
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1515
Here it looks better
but… read the fine print!
AuAu normalizedto e+e-
Almost the same plot
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1616
Intriguing scaling/universality for multiplicity/participant
ee
pp
AA central
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1717
Look more closely at total multiplicity per Npart
Proportionality,but higher than for ppat the same energy
pp systematically lower
WNM does not work
for Au - Au
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1818
Still, the scaling with NStill, the scaling with Npartpart
is surprisingis surprising
Au+Au35-40%,Npart = 98
Cu+CuPreliminary
3-6%, Npart = 96
62.4 GeV
Cu+CuPreliminary
3-6%, Npart = 100
200 GeV
Au+Au35-40%, Npart = 99
PHOBOS
dN/dPHOBOS
and not only for total multiplicities ::
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 1919
Cu+Cupreliminary
Au+Au
dydp/NdN
dydp/NdR
Tpp2
coll
TAA2
AA
PHOBOS Au+Au PRL 94,082304(2005) PLB578,297(2004) Cu+Cu PRL(2006) accepted
This ‘geometric’ scaling with Npart worksnot only for soft (low pt) data!
(courtesy ofBarbara Wosiek)
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2020
I jeszcze nowe dane:I jeszcze nowe dane:
Gęstość barionównetto(ale tylkow midrapidity)
też się skalujez Npart
(PHOBOS, nucl-ex z 30.09.06)
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2121
A very specific come-back of A very specific come-back of WNMWNM
A.Białas & W.Czyż, first presented in Zakopane in 2004:a two-component WNM to describe d-Au at 200 GeV/c
Basic assumption:Superposition of independent contributionsfrom WN in the projectile and the targetApplies not only to the total charged multiplicitybut longitudinal spectra also
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2222
Density of particles in A – B collision:
)()( yFwyFwdy
dNBBAA
AB
The model requires )()( yFyF AB
And the first consequence is
)(2
1)0( BAAB wwyR
(F is a contribution from a singlewounded nucleon)
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2323
A. Białas, W. Czyż, Acta Phys. Pol. B36, 905(2005)
PHOBOSdAu 200 GeV
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2424
For full (pseudo)rapidity range: construct symmetric and antisymmetric component
d
dN
d
dNG
)()()(
aa )(2
)(
dAu wwG )(
2)(
dAu ww
G
The Model predicts:
2/][
)()(
cd
cAuc
cc
ww
G
where
(c– centrality}
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2525
Symmetric and antisymmetric part Symmetric and antisymmetric part of the inclusive xsection for several of the inclusive xsection for several
centralities dAu:centralities dAu:ddN
ce
ntr
alit
y
Comparison Model vs data (PHOBOS) for several centralities
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2626
Next step: Next step:
)()0()( ppd
dNRdAu
d
dNdAu
Model looks OK for d hemispherenot so good for Au
Next step: determine contribution from a single wounded nucleon
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2727
Two step particle production:1. Multiple color exchanges between partons from projectile
and target2. Particle emission from color sources created in step 1
(AB+Marek Jeżabek, Phys.Lett.B590,233 (2004))
The contribution from one wounded nucleonextends over (almost) full rapidity rangeThere is a big difference between its symmetricand antisymmetric part
Authors interpretation:
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2828
Revival of wounded quarks Revival of wounded quarks concept for A - Aconcept for A - A
S. Eremin & S.Voloshin, Phys.Rev.C67, 064905 (2003)
As Recall:at midrapidity –increase of dN/dper participantwith Npart
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 2929
Try NTry Nq-partq-part instead of N instead of NNpartNpart
To calculate: use same Nuclear Overlap Calculation(K.J.Eskola et al.,Nucl.Phys.B323,37(1989))as for N-N, but change density and
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3030
Calculating NCalculating Nn-partn-part and N and Nq-partq-part
partnN partqN
fm53.0d
fm)A86.0A12.1(R
fm17.0n
]d/)Rrexp[(1
n)r(n
3/13/1
30
0A
}]A
)s(T1[1){bs(sTd
}]B
)bs(T1[1){s(sTd|N
AAinelNN
B2
BBinelNN
A2
ABpartn
)zb(dzn)b(T 22A
30
q0 fm51.0n3n
9/inelNNqq
Mass numbers of collidingnuclei are 3 times larger,but their size is the same.
For pp the same procedurewith A=B=3, hard sphere R=0.8fm.
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3232
Compare NCompare NNN, N, Nqq
two versions of qq
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3333
Eremin & Voloshin
Scale bynucleon participants
Scale byquark participants
increase
perhaps slight decrease
(full vs empty: different
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3434
How does it work at SPS?
Netrakanti & Mohanty, PRC70(2004)027901
look at WA98 data 158 GeV/n Pb-Pb
Nucleon participants
Quark participants
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3535
Bhaskar De & S.Bhattacharyya PRC 71(2005) 024903look at NA49 data (SPS)
Noticelog scale…
nucleons
quarks
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3636
Caveat:
D & B write about ‘integrated yields’ in figure caption, but show integrated yields for p, Kand midrapidity values for pbar, d
(plots to be re-done by NA49)
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3737
Moreover...
When you put together light and heavy nuclei,you see that Npart is not a good scaling variablefor strange particles
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3838
Now for the energy Now for the energy dependence:dependence:
R.Nouicer, nucl-ex/051244,2005
One step further: energy dependenceR.Nouicer nucl-ex/0512044
Midrapidity charged particle density normalized to:
Nucleon participants Quark participants
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 3939
Again: Caveat
The author normalizes pp data by the number of quark participants for ‘most central’ pp collisions
Is this a correct procedue?
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 4040
p+p 200 GeV
(Nq-part)inclusive 2.4 (Nq-part)central 3.5
(plot stolen from Barbara Wosiek,who noticed the problem)
Semin.IFD/IPJ 06.10.06Semin.IFD/IPJ 06.10.06 Zakopane, June 06, HBZakopane, June 06, HB 4141
An attempt at a summary:An attempt at a summary:
Wounded nucleons remarkably successful in parametrization of global characteristics of particle production
Nobody expects everything to be just a multiplication of N-N but the proportionality
looks intriguing
Wounded quarks - perhaps better scaling?