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[email protected] CERN, June 4-8, 2012 . Use of pA for benchmarking AA collisions. Xin -Nian Wang Central China Normal University & Lawrence Berkeley National Laboratory. Any progress between 2002-2012?. INT/RHIC Winter Workshop 2002 on First Two Years of RHIC: Theory versus Experiments

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Pa@lhc

[email protected]

CERN, June 4-8, 2012

Use of pA for benchmarking AA collisions

Xin-Nian Wang

Central China Normal University & Lawrence Berkeley National Laboratory


Any progress between 2002 2012

Any progress between 2002-2012?

INT/RHIC Winter Workshop 2002 on

First Two Years of RHIC: Theory versus Experiments

December 13 - 15, 2002

Institute for Nuclear Theory, Seattle, Washington


Any progress between 2002 20121

Any progress between 2002-2012?

INT/RHIC Winter Workshop 2002 on

First Two Years of RHIC: Theory versus Experiments

December 13 - 15, 2002

Institute for Nuclear Theory, Seattle, Washington


Pa versus aa @rhic

pA versus AA @RHIC

RBRC Workshop on: New Discoveries at RHIC, May 15, 2004


2002 d j vu

2002 déjà vu?


Benchmarking aa collisions

Benchmarking AA collisions

Cold Nuclear Matter (CNM) effects:

  • Gluon saturation and nuclear shadowing

  • Transverse momentum broadening

  • Parton energy loss in CNM

    • modified beam PDF

    • Parton energy loss in hadronic phase

  • Color flow and hadronization


Multiple scattering in cold nuclear matter

Multiple scattering in cold nuclear matter

DIS of large nuclei

DY production in pA


Twist expansion of multiple scattering

Twist expansion of Multiple Scattering

....

k

p

Leading twist (LH)

Higher twist


Pa lhc

Liang & XNW (2007)


Leading twist parton distribution in dis

Leading-twist partondistribution in DIS

....

k

p

Belitsky, Ji and Yuan (2002)


Jet transport

Jet Transport


P t broadening

pT broadening


Pt broadening in dis and dy

pT broadening in DIS and DY

eA HERMES (2007)

DY in pA E866


Complete lo up to twist 4 dis

Complete LO up to twist-4 DIS

Gao. Liang & XNW (2010)

Song, Gao, Liang & XNW(2011)


Parton energy loss in cold nuclear matter

Parton energy loss in cold nuclear matter

DIS of large nuclei

DY production in pA


Leading twist drell yan

Leading Twist Drell-Yan

Factorization: Separation of short- from long-distance

NLO partonic diagram to PDF, LO + NLO collinear part

Scaling violation – DGLAP evolution


Annihilation like processes q gq

Annihilation-like processes (q+gq)

  • Double scattering:

  • Single-triple interference:


Compton like processes g gq

Compton-like processes (g+gq)

  • Double scattering:

  • Single-triple interference:


Lpm interference in dy

LPM interference in DY

  • Final result for particular example

Hard-Hard

Soft-Hard

19


Medium modified projectile pdf

Medium modified projectile PDF

  • Modified quark distribution - Vacuum + Medium

Modified splitting function

  • Modified DGLAP evolution


Quark gluon correlation functions

Quark-gluon correlation functions

  • “factorized” gluon-quark correlation function

  • Jet transport parameter

21


Modified fragmentation function in dis

Modified fragmentation function in DIS

Guo, XNW 2000


Modified dglap equations

Modified DGLAP Equations

Modified splitting functions


Dis of large nuclei

DIS of large nuclei

Deng & XNW (2010)


Nuclear effects in drell yan

Nuclear effects in Drell-Yan

Energy loss VS. Shadowing (FNAL-E866 ELab = 800 GeV)

25


Parton energy loss in drell yan

Parton energy loss in Drell-Yan

Energy loss VS. Shadowing (FNAL-E906 ELab = 120 GeV)

FNAL-E906 provide unambiguous measurement of initial state energy loss

26


Pt broadening in pa collisions

pT broadening in pAcollisions

XNW, Phys. Rev. C61 (2000) 064910


Pt broadening in pa collisions1

pT broadening in pA collisions

XNW, Phys. Rev. C61 (2000) 064910

Eskola, Paukkunen & Salgado

JHEP 0904 (09)065


Pt broadening or anti shadowing

pT broadening or anti-shadowing?

Talk by IlkkaHelenius


Pt broadening in hijing2 1

pT broadening in HIJING2.1

kT kick in p+A collisions:

KT broadening of initial and final partons, with Gaussian distribution

Multiple scattering

Energy dependence of the width in Gaussian distribution


Shadowing in hijing

Shadowing in HIJING

Nuclear shadowing:

Li & XNW, Phys.Lett.B527, 85(2002)

Gluon, fit to the RHIC

Quark, fixed on DIS


R pa for final hard partons

RpA for final hard partons

Cronin Effect at fix pT

Shadowing suppress RpAat low pT region (small x region)

There is suppression at large pT?


Hard versus soft interaction

Hard versus soft interaction

1st Hard Scattering

1st Hard Scattering

2nd Hard Scattering

2nd Hard Scattering

1st Soft Scattering

2nd Soft Scattering

……

1st Soft Scattering

2nd Soft Scattering

……

De-coherent Hard Collision (DHC) : Soft-Hardde-coupled in multiple scattering in HIJING

……


Hard versus soft interaction1

Hard versus soft interaction

For DHC without shadowing, RpA is 1 at large pT


Flavor correlation in projectile

Flavor Correlation in projectile

Valence Quark Number Conservation

Quark availability is less in multiple scattering

HIJING takes the limiting case:

If a quark has been scattered once, only gluon available for latter scattering


Enhanced gluon spectra in pa

Enhanced gluon spectra in pA

the Q/G ratio in p+A is smaller at large pT.

Gluon fragmentation function is softer than quark


Color flow hadronization in pa

Color flow & hadronization in pA

String fragmentation

Independent fragmentation

Projectile in p+p

Projectile in p+A


Hadron spectra modification in pa

Hadron spectra modification in pA


Implications of cnm effect on aa

Implications of CNM effect on AA

All initial CNM effects have strong impact-parameter dependence.In the center of overlapping region where CNM effects are strongest, jet quenching is also the strongest, so final effect in AA is small after jet quenching.

Electro-weak particle production in AA are more sensitive to the CNM effects


Jet quenching in hadronic phase of qgp

Jet quenching in hadronic phase of QGP

Chen, Greiner, Wang, XNW, Xu (2010)

30% quenching from

hadronic phase


Summary

Summary

Multiple scattering in eA and pA important

qhat in cold nuclear matter 0.02 GeV^2/fm

Parton energy loss negligible in pA at y=0

Cronin effect from pT broadening is different from anti-shadowing

The Cronin peak disappears in CGC because of evolution

Parton energy loss during hadronic phase in AA collisions is non-negligible


Summary1

Summary


Azimuthal asymmetry

Azimuthal Asymmetry


Rpa for final hadron

RpA for Final Hadron

This flavor correlation suppress RpA of final hadron at large pT

Lund Fragmentation


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