Op en Charm Ph ysics at SPS and RHIC Ziw ei Lin T exas - - PDF document

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Op en Charm Ph ysics at SPS and RHIC Ziw ei Lin T exas - - PDF document

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Op en Charm Ph ysics at SPS and RHIC Ziw ei Lin T exas A&M Univ ersit y Pro duction in pp Leading-Order Pro cesses Higher-Order Results F ragmen tation F unctions T otal Cross Section vs Data Pro duction

slide-1
SLIDE 1 Op en Charm Ph ysics at SPS and RHIC Ziw ei Lin T exas A&M Univ ersit y Pro duction in pp Leading-Order Pro cesses Higher-Order Results F ragmen tation F unctions T
  • tal
Cross Section vs Data Pro duction in AA Scaling Observ ables at RHIC High-p ? Suppression from Energy loss Mid-p ? Enhancemen t from Radial Flo w at SPS ? from Radial Flo w at RHIC Op en Charm in pA at RHIC Summary R WW'99, 1/9/99
slide-2
SLIDE 2 Wh y do w e need
  • p
en c harm? J = suppression suppression
  • f
total c harm
  • r
  • nly
J = Thermal dileptons needs go
  • d
understanding
  • f
con tin uum dilepton sp ectra Thermalization sensitiv e to energy loss and thermalization eects R WW'99, 1/9/99
slide-3
SLIDE 3 Op en Charm Pro duction in pp

c c Gluon Leading Order Diagrams Quark _ c c

  • X1

X2

Com bridge, NPB151,429(79) Scale set b y m c ' 1:3 GeV P erturbativ e QCD w
  • rks
reasonably w ell: d d 3 p / Z dx 1 f (x 1 )dx 2 f (x 2 ) d ^
  • d
^ t R WW'99, 1/9/99
slide-4
SLIDE 4 NLO c harm pro duction: Hea vy quark pro duction at O ( 3 ): Nason et al, NPB303,607(88); 327,49(89) Beenakk er et al, PRD40,54(89); NPB351,507(91) see Nason hep-ph/9811468 for more K-factor
  • LO
+N LO LO Almost constan t
  • v
er the whole phase space! K far from 1: imp
  • rtance
  • f
higher
  • rder
terms. V
  • gt,
ZPC71,475(96) R WW'99, 1/9/99
slide-5
SLIDE 5 Charm F ragmen tation in Hadropro ductions e + e
  • data
suggests the P eterson form a : D (z ) / 1 z [1
  • 1=z
  • =(1
  • z
)] 2 E769, consisten t with EITHER: bare c harm quark sp ectra OR :P eterson plus in trinsic < k 2 ? >
  • f
2 GeV 2 E706, higher p ? co v erage, consisten t with P eterson plus in trinsic < k 2 ? >
  • f
1
  • 2
GeV 2

10 -5 10 -4 10 -3 10 -2 10 -1 1 10 1 2 3 4 5 6 7 8

pT (GeV/c) dσ/dpT (µb/(GeV c

  • 1 nucleon))

π-N→ D±X at 515 GeV/c

Data NLO QCD Charm quarks NLO QCD + Frag. + <kT

2>=3.0 (GeV/c)2

NLO QCD + Frag. + <kT

2>=2.0 (GeV/c)2

NLO QCD + Frag. + <kT

2>=1.0 (GeV/c)2

NLO QCD + Frag. + <kT

2>=0.0 (GeV/c)2

xF > -0.2

a z
  • p
D =p c ,
  • =
0:06(LO), 0:02 (NLO);
  • /
1=m 2 Q R WW'99, 1/9/99
slide-6
SLIDE 6 D
  • D
correlation in hadropro ductions a : High-p ? direct photon and
  • data
suggests: < k 2 ? >' 1 GeV 2 +C Q 2 ) Op en c harm hadropro duction most consisten t with P eterson fragmen tation+parton in trinsic k ? a W A92, PLB385,487(96) R WW'99, 1/9/99
slide-7
SLIDE 7 T
  • tal
Cross Section vs Data F rom leading-order calculation:

100 200 300 400 500 600 700 800 900 1000

Plab (GeV) 1 10 100

Lin, Phys Rev C

MRSA, mc=1.3GeV, K=2.5 MRSA, mc=1.4GeV, K=2.5 GRV−HO, mc=1.3GeV, K=3

σ(pp−>cc X) (µb)

_

NA34 NA27 E743 E789 E653

Large uncertain t y from scale and quark mass. Ho w ev er, data helps to constrain parameters, NLO & resummation help, making ratios helps(systematic studies) R WW'99, 1/9/99
slide-8
SLIDE 8 Op en Charm Pro duction in AA Scaling from pp to AA (shadowing
  • n
n uclear structure function will b e discussed later) d c
  • c
AB d 2 b / T AB (b)
  • c
  • c
pp

50 100 150 200

sqrt(s) (GeV)

1 10 100 1000

µb

Open Charm production up to RHIC energy

MRSA, 1.3GeV, K=2.5 MRSA, mc=1.4GeV, K=2.5 GRV−HO, mc=1.3GeV, K=3

NA50 RHIC

pp → c c

_

  • c
  • c
pp ' 350b (at 200GeV), T AA (0) ' 30=mb ) large
  • p
en c harm pro duction at RHIC! F
  • r
an a v erage cen tral Au + Au ev en t: N c
  • c
( ~ b = 0) = T AA (0)
  • c
  • c
pp ' 10 R WW'99, 1/9/99
slide-9
SLIDE 9 Small secondary c harm pro duction

_ c c Minijets Pre-equilibrium charm production from minijets

0.0 2.0 4.0 6.0 8.0 10.0 charm PT (GeV) 10

−6

10

−5

10

−4

10

−3

10

−2

10

−1

10

Ed3N/d3p(Y=0) (GeV−2)

additional charm production

Initial fusion strong η−y correlation Bjorken correlation fireball case initial fusion pre-thermal thermal ideal thermal

pT (GeV/c) Au+Au(b=0) s

1/2=200 GeV

  • Fig. 5

dN/dyd2pT(y=0) (GeV-2c2)

10

  • 9

10

  • 8

10

  • 7

10

  • 6

10

  • 5

10

  • 4

10

  • 3

10

  • 2

10

  • 1

1 1 2 3 4 5 6 7 8

Lin & Gyulassy ,PR C51,2177(95) L
  • ev
ai,M
  • uller&W
ang,PR C51,3326(95) R WW'99, 1/9/99
slide-10
SLIDE 10 Observ ables from
  • p
en c harm:
  • D-mesons:
D ! K
  • leptons:
D ! e
  • ,
D !
  • dileptons
from D/
  • D
pairs: D ! e +
  • ,
  • D
! e
  • )
{ lik e-sign pairs: e + e + ; e +
  • +
;
  • {
  • pp
  • site-sign
pairs: e + e
  • ;
e +
  • ;
  • correlated
pairs: from
  • ne
D/
  • D
pair
  • uncorrelated
pairs: from t w
  • D/
  • D
pairs R WW'99, 1/9/99
slide-11
SLIDE 11 RHIC ST AR? PHENIX? PHENIX, go
  • d
PHENIX,go
  • d
R WW'99, 1/9/99
slide-12
SLIDE 12 Large Dilepton Yield from Charm Deca ys Larger than Drell-Y an, PHENIX is able to see those: from Akiba R WW'99, 1/9/99
slide-13
SLIDE 13 Hea vy quark ma y ha v e energy loss Sh ury ak, PR C55,961(97); Lin, V
  • gt
& W ang, PR C57,899(98)

2 4 6 8 10

D−meson pt (GeV)

10

−3

10

−2

10

−1

10 10

1

10

2

dN/dpt (GeV

−1)

charm quark pt spectrum

9.94E6 ccbar events

before energy loss after energy loss thermalized part

  • Suppressions
  • f
high-p ? D mesons, as w ell as high-p ? leptons and high-M dileptons from c harm deca ys.
  • No
evidence
  • f
jet quenc hing for pions A t SPS a ! large formation time for fast pions?
  • hea
vy quarks migh t b e the b est prob e
  • f
energy loss Figure: assumed dE/dx=-1GeV/fm, Lin, V
  • gt
& W ang, PR C57 a W ang, PRL81,2655(98) R WW'99, 1/9/99
slide-14
SLIDE 14 PHENIX will then see a large suppression: E e > 1 GeV,
  • e
2 (0:35; 0:35); E
  • >
2 GeV, j
  • j
2 (1:15; 2:44)

2 4 6 8 10

−9

10

−8

10

−7

10

−6

10

−5

10

−4

10

−3

µ

+µ − Spectra from Open Charm at PHENIX

flow: de/dx=−2GeV/fm, T=150MeV 2 4 6

eµ Spectra from Open Charm at PHENIX

flow: de/dx=−2GeV/fm, T=150MeV 2 4 6

10

−9

10

−8

10

−7

10

−6

10

−5

10

−4

10

−3

e

+e − Spectra from Open Charm at PHENIX

flow: de/dx=−2GeV/fm, T=150MeV

  • riginal charm

suppressed charm

  • riginal bottom

suppressed bottom Drell−Yan

Ml

+ l − (GeV)

dN/dMl

+ l −(GeV −1)

e

+e −

eµ µ

+µ −

Lin, V
  • gt
& W ang, PR C57,899(98) R WW'99, 1/9/99
slide-15
SLIDE 15 Enhancemen t
  • f
dileptons from NA50 In termediate mass region: M
  • +
  • >
1:5 GeV from Scomparin, SQM'98 R WW'99, 1/9/99
slide-16
SLIDE 16 Enhancemen t from Charm Radial Flo w Hadron m T in v erse slop e T ef f / mass:

1 2 3 4 mT−mD (GeV/c

2

) 10

−5

10

−4

10

−3

10

−2

10

−1

10

dN/mTdmT Initial: 160MeV Final: 290MeV (PYTHIA)

Then D-meson w
  • uld
b e harder: mid-p ? D-mesons enhanced. Ho w ev er, no c hange in the total n um b er R WW'99, 1/9/99
slide-17
SLIDE 17 Enhancemen t vs T ef f

150 200 250 300 350

D−meson Teff (MeV)

1 2 3 4

change of Dimuon yields (M>1.5GeV)

Enhancement at SPS Initial Final

Simulated NA50 acceptance

Lin & W ang, PLB in press. Detailed study can b e done in a cascade mo del. Will this enhancemen t happ en at RHIC? p s Initial T D ef f Final T D ef f (GeV) (MeV, PYTHIA) (MeV) 17 (SPS) 160 290? 200 (RHIC) 430 5500 (LHC) 500 In addition to energy loss at RHIC, radial flo w ma y soften D-meson sp ectrum & lead to a SUPPRESSION
  • f
dileptons from c harm, instead
  • f
the enhancemen t at SPS. R WW'99, 1/9/99
slide-18
SLIDE 18 Other Suggestions
  • n
IMR Dilepton Enhancemen t
  • A)
a 1 annihilation a : { enhancemen t comes mainly from the
  • a
1 coupling to (1700); { ho w ev er, this coupling is uncertain
  • B)
Secondary Drell-Y an pro cesses b : { mainly from in teractions b et w een pro duced mesons and bary
  • ns
{ sensitiv e to hadron formation time
  • F
{ eect v aries from 30% to 3 for P b + P b
  • Ho
w to test these scenarios at RHIC? { A) scales with (pion n um b er) 2 ) bigger enhancemen t at higher energies { B) scales with (pion n um b er) ho w ev er, nite
  • F
w
  • uld
probably kill the main con tribution due to the h uge
  • factor
{ Suppression exp ected from the
  • p
en c harm scenario a Li & Gale: Nucl.Ph ys.A638,491c(98) b Spieles et al, Eur.Ph ys.J.C5,349(98) R WW'99, 1/9/99
slide-19
SLIDE 19 Op en Charm in pA at RHIC: a unique place to measure gluon shado wing d c
  • c
pA d 3 p / Z dxf (x) Z dx A d ^
  • d
^ t f (x A ) S (x A ; Q 2 ) Nuclear shado wing
  • f
Large effects
  • n
quark densities
  • bserv
ed. global
  • bserv
ables at RHIC: Gluon shado wing to
  • (indirectly):
(Ev en Larger effects
  • n
gluon-dominated pro cesses) Gousset & Pirner,PLB375,349(96). W ang & Gyulassy ,PRD44,3501(91) R WW'99, 1/9/99
slide-20
SLIDE 20 Mapping Gluon Shado wing in pA at RHIC:

−5 −3 −1 1 3 5

yl

+ l −

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

Dilepton dσ/dy ratio: pA/(A*pp)

M=1 GeV M=2 GeV M=4 GeV

e e eµ µ e µµ µ µ

Relate dileptons rapidit y with Bjork en x A : ln x A
  • y
l + l
  • +
ln( M +
  • )

10

−3

10

−2

10

−1

10

xA

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Dilepton dσ/dy ratio: pA/(A*pp) Gluon shadowing input M=1 GeV M=2 GeV M=4 GeV

Lin & Gyulassy , PRL77,1222(96) & determined from c harm fragmen tation and deca y kinematics R WW'99, 1/9/99
slide-21
SLIDE 21 Summary
  • Op
en c harm pro duction in pp { reasonably describ ed b y NLO pQCD { b est t with P eterson's fragmen tation plus hadron in trinsic k ?
  • Op
en c harm pro duction in AA at RHIC { large yield
  • f
  • p
en c harm & dileptons from their deca ys { great co v erage
  • f
  • p
en c harm
  • bserv
ables { high p ? migh t b e the b est prob e
  • f
energy loss { radial
  • w
ma y c hange sp ectra at medium p ? { dilepton sp ectra from
  • p
en c harm deca ys in pA can map the gluon shado wing in n uclei { m ust b e studied w ell b efore
  • ther
issues can b e addressed w ell, suc h as thermal dileptons and J = suppression
  • In
1=2 y ear RHIC will start to answ er! R WW'99, 1/9/99