forward physics at rhic and lhc report from the lawrence workshop
DESCRIPTION
Forward Physics at RHIC and LHC report from the Lawrence Workshop. F.Videbæk BNL. Program of meeting http://agenda.cern.ch/fullAgenda.php?ida=a044385. Color Glass Condensate A.Mueller – Review of HERA data R.Debbe -BRAHMS forward program B.Wysloch -The forward detectors of CMS - PowerPoint PPT PresentationTRANSCRIPT
19 November 2004RHIC-II workshop, BNL 1
Forward PhysicsForward Physicsat RHIC and LHCat RHIC and LHC
report from the Lawrence Workshopreport from the Lawrence Workshop
F.VidebækF.Videbæk
BNLBNL
19 November 2004RHIC-II workshop, BNL 2
Program of meetingProgram of meetinghttp://agenda.cern.ch/fullAgenda.php?ida=a044385
Color Glass CondensateA.Mueller – Review of HERA dataR.Debbe -BRAHMS forward programB.Wysloch -The forward detectors of CMSL.McLerran -Color Glass Condensate. Physical Picture and
simple questionsP.Armesto -geometric ScalingK.Tuchin – Forward Physics at RHIC. Onset of SaturationR.Hwa – Forward Production by Parton RecombinationD.Kahana - - Initial thoughts for D+A
Heavy Ion systematicI.Bearden – BRAHMS Au-Au resultsR.Hollis – limiting fragmentationG.Stephans – fixed target at RHIC
SPINF.Videbaek – BRAHMS spinJ.Qiu – RHIC spinJ.Ralston – disentangling forward physics
19 November 2004RHIC-II workshop, BNL 3
McLerran: Phase Space of Interesting Physics
Small x: Potentially large region in Q
Matter has universal properties at small x:Only variable is the saturation momentum!
Is this true?
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Crucial Observations:
Geometric Scaling in epLimiting Fragmentation
Renormalization Group
Are these connected by universal QCD properties at large y.
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Developing Theoretical Story:Developing Theoretical Story:
Fluctuations are important:Evolution equations from low density to high density
are fluctuation dominated.
Event by event studies with wide coverage in x and/or pT?What are predictions for fluctuation spectra in observables?
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Deep Inelastic Scattering eA has no direct access (first order) to the gluon PDF it measures q - qbar
To access gluon PDF the preferred system would be p+A thru “gluon-initiated” g+q or g +g interactions.
The “benefits” of p+A systemsThe “benefits” of p+A systems
R.Debbe
19 November 2004RHIC-II workshop, BNL 9
At 4 degrees (y~3 for pions) and pT = 1 GeV/c one can reach to values as low of x2 ~ 10-4
But one has to remember that that low number is a lower limit, not a typical value.
From Gusev, Strickman, and Vogelsang.
Most of the data collected at 4 degrees would have x2~0.01
19 November 2004RHIC-II workshop, BNL 10
K.TuchinK.TuchinForward Physics at RHIC onset of saturationForward Physics at RHIC onset of saturation
19 November 2004RHIC-II workshop, BNL 11
Scaling of charm spectra with atomic Scaling of charm spectra with atomic number number AA(Kharzeev)(Kharzeev)
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Forward Production by Parton Recombination
Rudolph C. Hwa -- conclusionNo change of physics from <0 to >0.No multiple scattering or gluon saturation put in explicitly.Behaviors to checkβ, dependences pT spectra (a) pions
(b) protons If p/> 0.2, difficult forfragmentation
RCP well reproduced with only the recombination of
soft and shower partons.•Back-to-back jets•Di-hadron correlations
No conflict between CGC and recombination, only question is where?
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• Different rapidities provide different densities of the medium: Sensitive to the dynamics
• Largest medium effect at mid-rapidity?
• Rapidity dependent high-pT suppression factors: provide information on dynamical medium effect
Rapidity Dependent High-pRapidity Dependent High-pTT MeasurementMeasurement
Nucl-th/0108056, Polleri and Yuan
at fixed time
y~0
high-y
Nu
cle
ar
Mod
ificati
on
Facto
rBRAHMS forward rapidity
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Rcp for hRcp for h++ and h and h-- at at ~3.2~3.2 Rcp at ~3.2 for charged
hadrons
Strong centrality dependence:
Rcp(0-10%) < Rcp(20-40%)
No significant dependence
in 0<<3.2
Maximum at pT~2GeV/c
(rapidity independent soft-hard
transition?)
Systematic Errors
- 10-15% overall
- 10% p-by-p
Is this understood?
~3.2
~2.2~0
BRAHMS PRL 91 (2003)
BRAHMS Preliminary
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3D-Hydro+Jet3D-Hydro+Jet
PRC 68 (2003) 064902 Hirano and Nara
3D Hydrodynamic Simulation with Jet (pQCD/PYTHIA)
Qualitatively describe data with pseudo-rapidity dependence
19 November 2004RHIC-II workshop, BNL 18
Divergence at higher y :Associated K+ productionNo single source with
unique T and B
Strangeness with KaonsStrangeness with Kaons
RAPIDITY DEPENDENCE
High rapidity equivalent in certain ways to lower energy data at mid-rapidity? Can be used to explore baryon high-density matter ?
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p+p, d-Ap+p, d-A
UA5 (200-900) → Z.Phys.C 43 (1989) 1ISR (23.6,45.2) → Nucl.Phys B129 365 (1977)
d+Au data from nucl-ex/0409021p+Em referenced therein
Limiting Fragmentation Observations at PHOBOSLimiting Fragmentation Observations at PHOBOS Richard S Hollis, UICRichard S Hollis, UIC
19 November 2004RHIC-II workshop, BNL 20
Questions raisedQuestions raised
Several questions remainCentrality dependence for whole rangeCollision species dependenceWill Cu+Cu fit into Au+Au data systematics?Is this observation specific to η?Original hypothesis was for rapidity distributionsDoes each particle species exhibit the same features?Limiting fragmentation also seen for v2.
Should these measurements be done for identified hadrons?
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RHIC spin – Jianwei Qiu, Iowa S.U.RHIC spin – Jianwei Qiu, Iowa S.U.
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NN = -0.08 +- = -0.08 +- 0.005 +- [0.015] in 0.17 < x0.005 +- [0.015] in 0.17 < xFF < < 0.320.32
The SSA needs xf-pt coverage to disentangle phenomena (Collins, Sievers…)Jet-correlations studies important.
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Multiplicity and hermetic coverage to |Multiplicity and hermetic coverage to |ηη|<7|<7 Zero Degree EnergyZero Degree Energy Physics:Physics:
– CentralityCentrality– Limiting FragmentationLimiting Fragmentation– Peripheral and ultra-peripheral collisionsPeripheral and ultra-peripheral collisions– Low-x, Color-Glass CondensateLow-x, Color-Glass Condensate– DCC, Centauros, StrangeletsDCC, Centauros, Strangelets
Forward Region:B.Wyslouch
19 November 2004RHIC-II workshop, BNL 24
Emerging ThemesEmerging Themes
(Armesto) To clarify the role of saturation (scaling): To clarify the role of saturation (scaling): more data needed, e.g. more data needed, e.g.
• pp, pA and AA at 0 < y < 5 (Y -scan of Qs2).• pA with several A at b = 0 (A-scan of Qs2 ).• AA at different b (centrality evolution of multiplicities).• Correlations in pA for the same and different rapidities.
(Mueller) Need to understand the early times.• measurements from initial system ( jets, photons, di-leptons)
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(Tuchin) At RHIC we are starting to see a novel effects due to a quasi-classical regime of QCD - the Color Glass Condensate, first signatures of which where observed at HERA.
Future tests of CGC at RHIC y À 1: inclusive hadrons (V) open charm ? hidden charm ? di-leptons ? correlations and Fluctuations ?(McLerran) Fluctuations are important:Evolution equations from low density to high densityare fluctuation dominated.
Event by event studies with wide coverage in x and/or pT?What are predictions for fluctuation spectra in observables?
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(J.Qiu) RHIC spin
(discussion) -Can the connection between saturation and limiting fragmentation be clarified by additional high-y measurements for identified particles.•Should the options to investigate systems with large baryon density vs. rapidity or fixed target at lower energy be explored?•How firm is the evidence for CGC at RHIC?
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The pitch for Forward PhysicsThe pitch for Forward Physics
Many of the issues brought up at the workshop are Many of the issues brought up at the workshop are central to an enhanced forward physics program.central to an enhanced forward physics program.
The RHIC program The RHIC program isis on its way to implement this on its way to implement this for upgrades, and possible future detector.for upgrades, and possible future detector.
There are good reasons this should be a There are good reasons this should be a motivation and an integral part for the RHIC-II motivation and an integral part for the RHIC-II program.program.
Many of the points here have also been addressed in the Letter of Many of the points here have also been addressed in the Letter of Intent of a new detector for RHIC Intent of a new detector for RHIC http://www.bnl.gov/henp/pac0904.asphttp://www.bnl.gov/henp/pac0904.asp
Low-x physics will be important too at LHC. The Low-x physics will be important too at LHC. The opportunities for systematic measurements at opportunities for systematic measurements at RHIC with pA, AA makes it competitive.RHIC with pA, AA makes it competitive.