elena g. ferreiro universidade de santiago de compostela, spain
DESCRIPTION
Heavy Ion Collisions in the LHC Era 16 - 20 July 2012, Quy Nhon , Vietnam. J/ψ and ϒ production in proton+nucleus collisions : lessons from RHIC for the 2012 p+Pb LHC run. Elena G. Ferreiro Universidade de Santiago de Compostela, Spain. - PowerPoint PPT PresentationTRANSCRIPT
J/ψ and ϒ production in proton+nucleus collisions: lessons from RHIC for the 2012 p+Pb LHC run
Elena G. FerreiroUniversidade de Santiago de Compostela, Spain
in collaboration with F. Fleuret, J-P. Lansberg , N. Matagne and A. Rakotozafindrabe
EPJC61 (2009), PLB680 (2009), PRC81 (2010), NPA855 (2011), FBS53 (2012), arXiV:1110:5047
Heavy Ion Collisions in the LHC Era 16 - 20 July 2012, Quy Nhon, Vietnam
• If we focalise on p+A data (where no QGP is possible) only cold nuclear matter (CNM) effects are in play:
shadowing and nuclear absorptionEMC and energy loss
• A lot of work trying to understand A+A data (since J/y QGP signal)
• In fact, the question is even more fundamental: p+p data we do not know the specific production kinematics at a partonic level: (2→2,3,4) vs (2→1)
Quarkonium as a hint of deconfinement
Quarkonium as a hint of coherence
Quarkonium as a hint of QCD1
LHC p+Pb run
Motivation
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 1
ContentsOur goal:
To investigate the CNM effects and the impact of the specific partonic production kinematics
3 ingredients:• Quarkonium partonic production mechanism
• Shadowing • Nuclear absorption
• Results on J/y production @ RHIC and LHC
To extend our study to ϒ and other CNM effects : • fractional energy loss
• gluon EMC effect• • Results on ϒ and J/y production @ RHIC
• Results on ϒ @ LHC2E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 2
Background
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 3
Particle spectrum altered by interactions with the nuclear matter they traverse=> J/Y suppression due to final state interactions with spectator nucleons
• At low energy: the heavy system undergoes successive interactions with nucleons in its path and has to survive all of them => Strong nuclear absorption• At high energy: the coherence length is large and the projectile interacts with the nucleus as a whole => Smaller nuclear absorption
sabs @ mid y < sabs @ forward y?Rapidity dependence of nuclear absorption?
• Usual parameterisation:(Glauber model)
Nuclear absorption: a final cold nuclear matter effect
Energy dependence
In terms of formation time:
Sabs = exp(-r sabs L )nuclear matter density break-up cross section path length
5
C. Lourenço et al.
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 4
• Nuclear shadowing is an initial-state effect on the partons distributions• Gluon distribution functions are modified by the nuclear environment• PDFs in nuclei different from the superposition of PDFs of their nucleons
Shadowing: an initial cold nuclear matter effect
Shadowing effects increases with energy (1/x) and decrease with Q2 (mT)
shadowing
antishadowing
3
EMCThe shadowing corrections
depend on the partonic process producing the J/Ysince it affects kinematics (x,Q2)
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 5
On the kinematics of J/y production: two approaches
Investigating two production mechanisms (including pT for the J/y):
g+g → J/y• intrinsic scheme: the pT of the J/y comes from initial partons
Not relevant for, say, pT>3 GeVOnly applies if COM(LO, as
2) is the relevant production mechanism at low pT
g+g → J/y+g, gg,ggg,…•extrinsic scheme: the pT of the J/y is balanced by the outgoing parton(s)
COM (NLO, NNLO), CSM (LO, NLO, NNLO)
• CNM -shadowing- effects depends on J/y kinematics (x,Q2)
• J/y kinematics depends on the production mechanism =>
2→2, 3, 4
2→1
for a given y, larger x in extrinsic scheme => modification of shadowing effects
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 6
• in order to reproduce data @ RHIC: nuclear absorption sabs extrinsic > sabs intrinsic the kinematics matter for the extraction of sabs
2→2
g+g
→ J/y+g
2→1
g+g
→ J/y
• shadowing depends on the partonic process: 2→1 or 2→2
E. G. Ferreiro, F. Fleuret, J. P. Lansberg and A. Rakotozafindrabe PRC 81 (2010) 064911
How partonic kinematics affects CNM: J/y in d+Au @ RHIC
6E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 7
J/y in Au+Au @ RHIC: rapidity dependence
• The J/y suppression from shadowing is y-dependent Reminder: sabs taken as constant
• Can account for a part of the y-dependence of the most central data
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 8
“CEM NLO” before kT smearing “Traditional” 2 → 2
J/y in Pb+Pb @ LHC: centrality dependence vs data
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 9
“CEM NLO” before kT smearing “Traditional” 2 → 2
underlying partonic model
without kt smearing with kt smearing
kt smearing procedure is applied after the (x1,x2) integration
J/y in Pb+Pb @ LHC: centrality dependence vs data
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 10
Uncertainty bands:mF from 0.5 mT to 2 mT
(as done in pp for g(x,mF)
Something new… searching for other CNM effects:ϒ production
• Gluon EMC effect
• Fractional energy loss
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 11
Absorption: ϒ vs J/y
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 12
uncertainty principle: time needed – in their rest frame to distinguish the energy levels of the 1S and 2S states
RHIC: sϒ
abs < 1 mb
nPDF uncertainty on ϒ production in d+Au @ RHIC
• backward: ok within uncertainties• central: reasonable job • forward : clearly too high (for any σabs)
Physical interpretation• backward: EMC effect• central: antishadowing • forward : shadowing≈1 energy loss is needed
Extrinsic scheme: sabs=0 mb, sabs= 0.5mb , sabs= 1 mb in 3 shadowing models
16E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 13
Searching for new effects: gluon EMC on ϒ in dAu @ RHIC
antishadowingEMC
Let us try to increase the suppression of g(x) in the EMC region, thr shadow incert.:
we have used three of the EPS09 LO sets: one with a quark-like EMC gluon suppression, and the two limiting curves
Works better for backward region
E. G. F., F. Fleuret, J. P. Lansberg and A. Rakotozafindrabe arXiV:1110:5047
What about the forward region?E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 14
Searching for new effects: energy loss on ϒ in dAu @ RHIC
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 15
WORK IN PROGRESS, preliminary
Searching for new effects: energy loss on ϒ in dAu @ RHIC
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 16
WORK IN PROGRESS, preliminary
Work in progress: ϒ production @ LHC
• Shadowing effect is not smallRemember that in PbPb collisions at y = 0shadowing effect is squared compared to pPb
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 17
• Shadowing effect is not smallRemember that in PbPb collisions at y = 0shadowing effect is squared compared to pPb
• Energy loss also likely matters, in particular in the most forward rapidity
Work in progress: ϒ production @ LHC
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 18
• Shadowing effect is not small Remember that in PbPb collisions at y = 0 shadowing effect is squared compared to pPb
• Energy loss also likely matters• Overall, nuclear matter effects are not small
they should be accounted when analysing PbPb data
Work in progress: ϒ production @ LHC
E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 19
Conclusions
• for J/y d+Au collisions @ RHIC A+A collisions @ RHIC and LHC
CNM strong effects at both energy
• We have studied the influence of specific partonic kinematics
within 2 schemes: intrinsic (2→ 1) and extrinsic (2→2) pT
for different shadowings including nuclear absorption and different partonic models
• for ϒ in d+Au collisions @ RHIC:
EMC effect in the backward region fractional energy loss in the central & forward region• energy loss can also affect J/y @ RHIC•work in progress: ϒproduction @ LHChttp://phenix-france.in2p3.fr/software/jin/index.html
22E. G. Ferreiro USC ϒ and J/ψ production in pA: from RHIC to LHC HIC in the LHC Era 19 July 2012 20