Hot results from cold weather in a cool presentation

Hot results from cold weather in a cool presentation

Studying nuclear matter created in pp, dA and AA collisions

using charged kaons

Camelia MironovKent State University

… or the story about the importance of identified-particle studies in heavy-ion collisions

kaons are the lightest strange particles the most abundant important piece in deciphering the final state puzzles

kaons alone (truth for _any_ particle probably ) does not permit to draw too many conclusions

camelia mironovFebruary, 2005 3

Identification …

K charged daughter

K parent

KINK

V0 decay vertices

Ks + + -

p + -

p + +

or uses the V0s

- + -

+ + +

+ K -

K charged daughter

K parent

KINK

V0

V0 parent

V0 charged daugthers

Kμν (63%)Kππ0 (21%)

Charged charged + neutral

Do all these particles show anything plus to what unidentified charged hadrons show?


For outlook …

RELAX !!!!!! (and this is not for me )

Contrary to what my abstract might’ve let the impression, my talk won’t last 3 hours !!!

Though interesting systems by themselves, I will refer to pp and dA collisions only by means of better understanding the AA data

nuclear modification factors

identified particle correlations


RAB/RCP: h±

Npart: number of nucleons in overlap region

Nbin: number of inelastic nucleon-nucleon collisions (# binary collisions)

participants

Quantify the deviation from p+p collisions:

ησηddpdT

ddpNdpR

Tpp

AB

TAB

TAB/

/)(

2

2

=

<Nbin>/σinelp+p describes the

Nuclear Geometry

peripheralbinperipheral

centralbincentral

TCPNYield

NYieldpR

/

/)( =

Charged Hadrons:

Au + Au : RCP and RAA ~ suppression

d + Au : RCP and RdA ~ enhancement (Cronin effect – experimental observation and not the explanation)


AuAu: identified hadrons

ησηddpdT

ddpNdpR

Tpp

AB

TAB

TAB/

/)(

2

2

=

<Nbin>/σinelp+p describes the nuclear

geometry


centralbincentral

TCPNYield

NYieldpR

/

/)( =

Baryons suppressed Mesons suppressed BUT

Mesons ~ 1.5GeV/c

Baryons~ 2.5GeV/c

Mesons suppressed

Baryons enhanced

maxRAAp(uud)<maxRAA

Λ(uds)<maxRAAΞ(dss)


Au + Au: RCP Experiment & Theory

Recombination describes fairly well the baryon – mesons differences

Fries et al nucl-th/0306027

Reco for K0s and Λ+Λbar

Central(b=3fm) / Peripheral (b=12fm)

… same Hijing/BBbar v2.0

Topor-Pop et al (nucl-th/0407095)

Hijing/BBbar v2 0-10% / 60-90%

For K- + K+ and Λ+Λbar


R_AA: Experiment & Theory …

Hirano, Nara nucl-th/0307015 Topor-Pop (private comunication)

Hijing/BBv2.0

-Hijing + baryon junction + jet quenching + shadowing + Strong Color Field effects

nucl-th/0407095

Hydro + jet quenching -hydrodinamics combined with minijets which go through jet quenching in the hot medium

nucl-th/0307015


dAu: identified hadrons

ησηddpdT

ddpNdpR

Tpp

AB

TAB

TAB/

/)(

2

2

=

<Nbin>/σinelp+p describes the nuclear

geometry


centralbincentral

TCPNYield

NYieldpR

/

/)( =

in d+Au also a difference between mesons and baryons (smaller though)


RdA/RCP(dA): theory and experiment

1.Hwa, Yang nucl-th/0404066

Recombination (Oregon)

final state effect

Initial state elastic scatterings reproduce the general trend of the R_dA but NOT the particle species dependence

Kopeliovich, Nemchik, Schafer, Tarasov – Phys. Rev. Lett. 88(2002) 232303


So far …

RAB/RCP HAS TO BE TREATED SEPARATELLY (at least until an explanation/scaling for the RAA strangeness ordering will be find out – an attempt: canonical suppression picture – more in talk by M Lamont)

AuAu: the difference between mesons and baryons in the intermediate pT region is reproduced in several models: recombination, hydro+jet quenching etc

= need more/different probes/measurements to test the models

dAu: apart from the enhancement (as opposed to the suppression in AA) dA shows similar features as AA (like the differences between mesons and baryons)

So .. toward different measurements …


Hadronization ReCo(Oregon)…Mesons (qq) :

Recombination function known from recombination model

Hwa, Phys. Rev. D (1980).

Fqq(p1,p2) = T T + T S + S2 + S SQuark-antiQuark distribution

),,(),( 21212

2

1

1 pppRppFp

dp

p

dp

dp

dNp Mqq

M ∫=

Baryons (q1q2q3)

),,,(),,( 3213213213

3

2

2

1

1 ppppRpppFp

dp

p

dp

p

dp

dp

dNp Bqqq

B ∫=

Fq1q2q3(p1,p2) = T T T+ TT S + TS2 + S3+ TSS + SS2 + SSS


Two particle correlations: Hwa, Yang nucl-th/0407081

Trigger ParticleTrigger Particle

Associated Associated ParticlesParticles

Jet structure by two-particle correlation within the jet: must consider 4/5 partons to recombine

Trigger on pions and calculate the distribution of the associated particles (AuAu collisions)


Back sideBack side

Same side Same side



)()(ñ

),(ñ)D(

]1[

]2[

φφ Δ≡Δ∑

∑

eventtrigger

eventpairs

trigger

associatedtrigger

))*cos(**.()*

)(exp(*)

*

)(exp(*)( φ

σφφ

σφφφ Δ++

Δ−Δ−+

Δ−Δ−=Δ 2021

22

21 22

2

22

21

21 flowvbgaaF

, , ,

, , , ,

,,

1

2

t trigger high t trigger

t trigger low t associated low

p p

trigger cht trigger

trigger t trigger tp p

dN dNB dp

N dp dp= ∫ ∫

Azimuthal correlations language


-h correlations in AA

0-5% 10-30%5-10%

30-50% 50-70%


Strange-charged hadrons correlations …

Back sideBack side

Same side Same side



NOT YET

0-5%: same side yield vs trigger pT

Lambda acts different

There seem to be signs of particle specific phenomena in strange-charged hadrons correlations

NO significant particle species dependency

NO strong centrality dependency (need systematics studies)

BORING?Y. Guo (STAR) hep-ph/0403018


Strange-Strange correlations …

+e

−e 0Zq

q

jetsqqZee →→→−+ 0

Rapidity difference between identified hadron pairs

Hadron production at SLD

short-range, local correlations short-range compensation of quantum numbers

long-range correlations between opposite chargeleading particle production: ssbar events different from uubar or ddbar events


Strange-Strange hadrons correlations …

KK ussu +− ⇔ )()(____

NOT DONE (YET) - used to be ‘really lack of statistics’

- truth now: ‘lack of time’

Back sideBack side

Same side Same side



K

K

usuds

usuds

)()(

)()(

__

_________

DONE – even so, ‘lack of statistics’


Not much…Λ trigger: 2<pT<6 (GeV/c)

K assoc: 1.5< pT < pTtrigger (GeV/c)

Not much, but an interesting analysis to continue with


Over all …

ANSWER: Particle identification do offer plenty of surprises and do rises lots of new

questions (to which we don’t know yet the whole answer)

and more important High pT PID is essential in gaining more insight into hadronization

mechanisms and medium properties knowledge.


Thank you!


Bonus


FlowReaction plane

x

z

y M. Kaneta

Reaction plane = (collision impact parameter, beam direction)

)plane( )( PlaneReaction z,bRP

rr≡Ψ


Data Analysis Methods:

bgaaF +Δ−Δ

−+Δ−Δ

−=Δ )*

)((exp*)

*)(

(exp*)( 22

22

21

21

22

21

σφφ

σφφφ

))*cos(.()*

)(exp(*)

*

)(exp(*)( ,, φ

σφφ

σφφφ Δ++

Δ−Δ−+

Δ−Δ−=Δ 2021

22

21 222

2

22

21

21 flow

assoflowtriggervvbgaaF

pp:

Au + Au:

))*cos(.)cos(()*

)(exp(*)( ,,cos φφ

σφφφ Δ++Δ+

Δ−Δ−=Δ 2021

21 222

1

21 flow

assoflowtriggervvCbgaF

Gaussian Fit of back side:

Cosine Fit of back side (momentum balance):

Same Side

Back Side

Background

Parameters are compared for different fits for two different pT cuts as the function of centralities

><−=∑

2T

associatedtriggerassociatedtrigger

P

PN

)cos(ÄPP2)P,(PC T ϕ

Nicolas Borghini et al. Phys. Rev. C 62, 034902(2000).


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Hot results from cold weather in a cool presentation