stato della ricerca e prospettive in collisioni ultrarelativistiche nucleo-nucleo
DESCRIPTION
Stato della ricerca e prospettive in collisioni ultrarelativistiche nucleo-nucleo. Federico Antinori INFN Padova. Contenuto. Introduzione (QGP, SPS) Risultati principali di RHIC Prospettiva: “hard probes” (heavy flavour) non tratterò di FAIR (GSI, “bassa” energia). QCD phase diagram. - PowerPoint PPT PresentationTRANSCRIPT
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Stato della ricerca e prospettive Stato della ricerca e prospettive in collisioni ultrarelativistiche in collisioni ultrarelativistiche
nucleo-nucleonucleo-nucleoFederico AntinoriFederico Antinori
INFN PadovaINFN Padova
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ContenutoContenuto
Introduzione (QGP, SPS)Introduzione (QGP, SPS)
Risultati principali di RHICRisultati principali di RHIC
Prospettiva: “hard probes” (heavy flavour)Prospettiva: “hard probes” (heavy flavour)
non tratterò di FAIR (GSI, “bassa” energia)non tratterò di FAIR (GSI, “bassa” energia)
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QCD phase diagramQCD phase diagram
Tc ~ 170 MeV
~ 5 - 10 nuclear
Quark-Gluon Plasma
Hadron gas
Nuclearmatter
Neutron Star
SPSAGS
Early Universe LHCRHIC
Baryon density
Tem
pera
ture
c ~ 1 GeV/fm3
~ 10 s after Big Bang
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(Partial) Chiral Symmetry Restoration(Partial) Chiral Symmetry Restoration Confined quarks acquire an additional mass (~ 350 MeV) Confined quarks acquire an additional mass (~ 350 MeV)
dynamically, through the confining effect of strong interactionsdynamically, through the confining effect of strong interactions M(proton) M(proton) 938 MeV; m(u)+m(u)+m(d) = 10 938 MeV; m(u)+m(u)+m(d) = 1015 MeV15 MeV
Deconfinement is expected to be accompanied by a restoration Deconfinement is expected to be accompanied by a restoration of the masses to the “bare” values they have in the Lagrangeanof the masses to the “bare” values they have in the Lagrangean
As quarks become deconfined, the masses would go back to the As quarks become deconfined, the masses would go back to the bare values; e.g.: bare values; e.g.: m(u,d): ~ 350 MeV m(u,d): ~ 350 MeV a few MeV a few MeV m(s): ~ 500 MeV m(s): ~ 500 MeV ~ 150 MeV ~ 150 MeV
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Due predizioni storiche...Due predizioni storiche...
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Strangeness enhancementStrangeness enhancement restoration of restoration of symmetry -> increased production of ssymmetry -> increased production of s
mass of strange quark in QGP expected to go back to current mass of strange quark in QGP expected to go back to current valuevalue mmSS ~ 150 MeV ~ Tc ~ 150 MeV ~ Tc
copious production of ss pairs, mostly by gg fusion copious production of ss pairs, mostly by gg fusion [[Rafelski: Phys. Rep. 88 (1982) 331]Rafelski: Phys. Rep. 88 (1982) 331][Rafelski-Müller: P. R. Lett. 48 (1982) 1066[Rafelski-Müller: P. R. Lett. 48 (1982) 1066]]
deconfinement deconfinement stronger effect stronger effect for multi-strangefor multi-strange can be built recombining uncorrelated can be built recombining uncorrelated
s quarks produced in independent s quarks produced in independent microscopic reactions microscopic reactions
strangeness enhancement increasing strangeness enhancement increasing with strangeness contentwith strangeness content
[Koch, Müller & Rafelski: Phys. Rep. 142 (1986) 167][Koch, Müller & Rafelski: Phys. Rep. 142 (1986) 167]
s
u
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d
u d
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u dd
d
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d dd
dd
ds
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s s
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s
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s
s
s
s ss
sd d
dd
d
dd
u
uu
u
uuu
u
d
K+
u
+
+
-
p
-
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QGP signature proposed by Matsui and Satz, 1986QGP signature proposed by Matsui and Satz, 1986
In the plasma phase the interaction potential is expected to be In the plasma phase the interaction potential is expected to be screened beyond the Debye length screened beyond the Debye length D D (analogous to e.m. Debye (analogous to e.m. Debye screening)screening)
Charmonium (cc) and bottonium (bb) states with r > Charmonium (cc) and bottonium (bb) states with r > D D will not will not bind; their production will be suppressedbind; their production will be suppressed
Charmonium suppressionCharmonium suppression
For T ~ 200 MeV:For T ~ 200 MeV:DD ~ 0.1 – 0.2 fm ~ 0.1 – 0.2 fm216
1~TD
(very) rough estimate...(very) rough estimate...
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L’era dell’SPS...L’era dell’SPS...
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CERN heavy-ion programmeCERN heavy-ion programme 1994 to 20031994 to 2003 typically 4 - 6 weeks per year Pb nuclei @ 158 A GeV/ctypically 4 - 6 weeks per year Pb nuclei @ 158 A GeV/c
(40 GeV in 1999, 158 GeV In in 2003, + short 20, 30, 80 GeV runs)(40 GeV in 1999, 158 GeV In in 2003, + short 20, 30, 80 GeV runs) 9 experiments:9 experiments:
WA97WA97 ((silicon pixel telescope spectrometersilicon pixel telescope spectrometer: production of strange and : production of strange and multiply strange particles)multiply strange particles)
WA98WA98 ( (photon and hadron spectrometerphoton and hadron spectrometer: photon and hadron production): photon and hadron production) NA44 NA44 ((single arm spectrometersingle arm spectrometer: particle spectra, interferometry, particle : particle spectra, interferometry, particle
correlations)correlations) NA45NA45 ( (ee++ee-- spectrometer spectrometer: low mass lepton pairs): low mass lepton pairs) NA49NA49 ( (large acceptance TPClarge acceptance TPC: particle spectra, strangeness production, : particle spectra, strangeness production,
interferometry, event-by-event studies…)interferometry, event-by-event studies…) NA50NA50 ( (dimuon spectrometerdimuon spectrometer: high mass lepton pairs, J/: high mass lepton pairs, J/ production) production) NA52NA52 ((focussing spectrometerfocussing spectrometer: strangelet search, particle production): strangelet search, particle production) NA57NA57 ( (silicon pixel telescope spectrometersilicon pixel telescope spectrometer: production of strange and : production of strange and
multiply strange particles)multiply strange particles) NA60NA60 ( (dimuon spectrometer + pixelsdimuon spectrometer + pixels: dileptons and charm): dileptons and charm)
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A Pb-Pb collision at the SPSA Pb-Pb collision at the SPS ““Busy” events! Busy” events!
(thousands of (thousands of produced particles)produced particles)
High granularity High granularity detectors are detectors are employed (TPC, Si employed (TPC, Si Pixels,...)Pixels,...)
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Particle productionParticle production
Rapidity distribution for Rapidity distribution for negative hadrons negative hadrons (mostly pions) for (mostly pions) for central Pb-Pb collisions central Pb-Pb collisions (from NA49)(from NA49)
~ 2500 hadrons per ~ 2500 hadrons per collisioncollision
corresponding to an corresponding to an initial energy density of initial energy density of 2 – 3 GeV/fm3 2 – 3 GeV/fm3
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Strangeness enhancement at the Strangeness enhancement at the SPSSPS
Enhancement relative to p-BeEnhancement relative to p-BeEnhancement is larger for particles of higher strangeness content (QGP prediction!) up to a factor ~ 20 for
So far, no hadronic model has reproduced these observations (try harder!)
Actually, the most reliable hadronic models predicted an opposite behaviour of enhancement vs strangeness
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J/J/ suppression at the SPS suppression at the SPS measured/expected measured/expected
J/J/suppression vs estimated suppression vs estimated energy densityenergy density anomalous suppression sets anomalous suppression sets
in at in at ~ 2.3 GeV/fm ~ 2.3 GeV/fm33 ( (bb ~ 8 ~ 8 fm)fm)
effect seems to accelerate at effect seems to accelerate at ~ 3 GeV/fm ~ 3 GeV/fm33 ( (bb ~ 3.6 fm) ~ 3.6 fm)
this pattern has been this pattern has been interpreted as successive interpreted as successive melting of the melting of the c c and of the and of the J/J/
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What have we learned at the SPS?What have we learned at the SPS? We create a strongly interacting fireball in a state of very large energy We create a strongly interacting fireball in a state of very large energy
density, at which the very concept of individual, separated hadrons is not too density, at which the very concept of individual, separated hadrons is not too meaningfulmeaningful
At freeze-out (when the reinteractions between the produced particles cease) At freeze-out (when the reinteractions between the produced particles cease) the system is expanding at ~ ½ cthe system is expanding at ~ ½ c
The properties of this state are not explained in terms of those of a The properties of this state are not explained in terms of those of a conventional system of strongly interacting hadrons: we have found a new conventional system of strongly interacting hadrons: we have found a new “regime” for strongly interacting system, which has to be investigated further“regime” for strongly interacting system, which has to be investigated further
This state exhibits many features of the QGP, in particular the expected This state exhibits many features of the QGP, in particular the expected effects of deconfinement (J/effects of deconfinement (J/ suppression) and chiral simmetry restoration suppression) and chiral simmetry restoration (strangeness enhancement) are there. It looks like the partonic degrees of (strangeness enhancement) are there. It looks like the partonic degrees of freedom are activefreedom are active
in order to better understand the properties of this state we need to go to in order to better understand the properties of this state we need to go to higher energy higher energy RHIC, LHC RHIC, LHC conditions closer to ideal, harder probesconditions closer to ideal, harder probes
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The next step: RHICThe next step: RHIC Relativistic Heavy Ion Collider (RHIC) Relativistic Heavy Ion Collider (RHIC)
at Brookhaven National Lab (USA - NY)at Brookhaven National Lab (USA - NY)
Au-Au collision in STARAu-Au collision in STAR
ssNNNN = 200 GeV, = 200 GeV, 10 from SPS: 10 from SPS: higher energy densities, temperatures, expected QGP lifetimes, higher energy densities, temperatures, expected QGP lifetimes,
volumesvolumes QCD calculations more reliable QCD calculations more reliable improve our understanding! improve our understanding! 10 units rapidity span: better separation of central and 10 units rapidity span: better separation of central and
fragmentation regionsfragmentation regions
4 dedicated, complementary experiments: 4 dedicated, complementary experiments: 2 larger (2 larger (STARSTAR: hadronic signals, : hadronic signals, PHENIXPHENIX: leptonic, e.m. signals),: leptonic, e.m. signals), 2 smaller (2 smaller (PHOBOSPHOBOS, , BRAHMSBRAHMS) )
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RHIC HeadlinesRHIC Headlines Rather low multiplicityRather low multiplicity
Gluon saturation? (“Colour Glass”)Gluon saturation? (“Colour Glass”)
Large Elliptic Flow Large Elliptic Flow v2v2
High pHigh pTT Suppression Suppression RRcpcp, R, RAAAA
Suppression of Away-Side JetsSuppression of Away-Side Jets Plus an New Structure in Away-Side?Plus an New Structure in Away-Side?
Valence Quark Counting RulesValence Quark Counting Rules Recombination?Recombination?
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Particle multiplicityParticle multiplicity
Multiplicity per nucleon-nucleon collision increases Bjorken estimate of energy density: 5.5 GeV/fm3 Extrapolation to LHC: dNch/dy ~ 2500
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Colour Glass?Colour Glass? At small x, large A, saturation of gluon pdf’s?At small x, large A, saturation of gluon pdf’s?
would explain relatively would explain relatively low multiplicitylow multiplicity
1919
Elliptic FlowElliptic Flow Non-central collisions are azimuthally asymmetricNon-central collisions are azimuthally asymmetric
The transfer of this asymmetry to momentum space provides a The transfer of this asymmetry to momentum space provides a measure of the strength of collective phenomena measure of the strength of collective phenomena
Large mean free path Large mean free path particles stream out isotropically, no memory of the asymmetry particles stream out isotropically, no memory of the asymmetry extreme: ideal gas (infinite mean free path) extreme: ideal gas (infinite mean free path)
Small mean free pathSmall mean free path larger density gradient -> larger pressure gradient -> larger larger density gradient -> larger pressure gradient -> larger
momentum momentum extreme: ideal liquid (zero mean free path, hydrodynamic limit)extreme: ideal liquid (zero mean free path, hydrodynamic limit)
Reactionplane
In-planeOut
-of-p
lane
Y
XFlow
Flow
Reactionplane
In-planeOut
-of-p
lane
Y
XFlow
Flow
Reactionplane
In-planeOut
-of-p
lane
Y
XFlow
Flow
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Azimuthal AsymmetryAzimuthal Asymmetry
at low pat low pTT: azimuthal : azimuthal asymmetry as large as asymmetry as large as expected at hydro limitexpected at hydro limit
very far from “ideal very far from “ideal gas” picture of plasmagas” picture of plasma
...)2cos(2)cos(2121
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vvdydpp
dNdyddpp
dN
TTTT
flow" directed" cos1 v flow" elliptic" 2cos2 v
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RRcpcp, R, RAAAA, R, RdAudAu
AApp
AAAA
1YieldYield
NbinR
dAupp
dAudAu
1YieldYield
NbinR
central AA,
periphAA,
periph AA,
central AA,cp Yield
YieldNbin
NbinR
Yield/collision in central collisionsYield/collision in central collisionsYield/collision in peripheral collisionsYield/collision in peripheral collisions
Yield/collision in nucleus-nucleusYield/collision in nucleus-nucleus Yield/collision in proton-protonYield/collision in proton-proton
Yield/collision in deuteron-nucleusYield/collision in deuteron-nucleus Yield/collision in proton-protonYield/collision in proton-proton
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High pHigh pTT suppression suppression
High pHigh pTT particle particle production expected to production expected to scale with number of scale with number of binary NN collisions if no binary NN collisions if no medium effectsmedium effects
Clearly does not work for Clearly does not work for more central collisionsmore central collisions
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AA vs ppAA vs pp Differences can arise due to both initial-state and final-state Differences can arise due to both initial-state and final-state
effectseffects
[David d’Enterria]
2424
Centrality DependenceCentrality Dependence
Opposite behaviour with centralityOpposite behaviour with centrality Looks like suppression in AA is due to mediumLooks like suppression in AA is due to medium Parton energy-loss in the medium? (“Jet Quenching”)Parton energy-loss in the medium? (“Jet Quenching”)
Preliminary DataFinal Data
Au-AuAu-Au(“cold” matter and medium effects)(“cold” matter and medium effects)
dAudAu(only “cold” matter effects expected)(only “cold” matter effects expected)
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Azimuthal Correlations (pp)Azimuthal Correlations (pp) In high energy collisions In high energy collisions
particles are correlated in particles are correlated in azimuth due to jetsazimuth due to jets
e.g.: at RHIC in proton-e.g.: at RHIC in proton-proton collisions from STARproton collisions from STAR ““trigger” particle: trigger” particle:
4 < p 4 < pTT< 6 GeV/c< 6 GeV/c associated particles: associated particles:
ppTT > 2 GeV/c > 2 GeV/c
trigger
Adler et al., PRL90:082302 (2003), STAR
near-side
away-side
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Azimuthal CorrelationsAzimuthal Correlations away-side jet still present in dAuaway-side jet still present in dAu
but disappears in central AuAubut disappears in central AuAu
away-side jet quenched?away-side jet quenched?
trigger bias on jets produced trigger bias on jets produced close to surface?close to surface?
Adams et al., Phys. Rev. Let. 91 (2003)
hadronsleadingparticle
is this what happens?
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Two peaks?Two peaks? Disappearance of away jet in Disappearance of away jet in
central collisions at RHICcentral collisions at RHIC 4 < p4 < pTT(trig) < 6 GeV/c(trig) < 6 GeV/c ppTT(assoc) > 2 GeV/c(assoc) > 2 GeV/c
if pif pTT(assoc) is lowered, peak turns (assoc) is lowered, peak turns up again, but up again, but with strange shapewith strange shape:: 0.15 < p0.15 < pTT(assoc) < 4 GeV/c(assoc) < 4 GeV/c
(1/N
trig)
dN/d
()
STAR Preliminary
p+p Au+Au 5%trig4 6 GeV/c
0.15 4 GeV/cT
T
pp
Fit to near side: const. + gaussian + Borghini-cos(fixed)
stat. mom. conserv.Borghini et al.
free fit
stat. mom. conserv.Borghini et al.
[F. Wang: QM 2004][F. Wang: QM 2004]
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Similar results from PHENIX, tooSimilar results from PHENIX, too
(1/N
trig)
dN
/d()
STAR Preliminary
p+p Au+Au 5%trig4 6 GeV/c
0.15 4 GeV/cT
T
pp
Fit to near side: const. + gaussian + Borghini-cos(fixed)
stat. mom. conserv.Borghini et al.
free fit
stat. mom. conserv.Borghini et al.
(1/N
trig)
dN
/d()
STAR Preliminary
p+p Au+Au 5%trig4 6 GeV/c
0.15 4 GeV/cT
T
pp
(1/N
trig)
dN
/d()
STAR Preliminary
p+p Au+Au 5%trig4 6 GeV/c
0.15 4 GeV/cT
T
pp
Fit to near side: const. + gaussian + Borghini-cos(fixed)
stat. mom. conserv.Borghini et al.
free fit
stat. mom. conserv.Borghini et al.
Fit to near side: const. + gaussian + Borghini-cos(fixed)
stat. mom. conserv.Borghini et al.
free fit
stat. mom. conserv.Borghini et al.
Low pLow pTT associated associated particles seem to peak particles seem to peak ~ 1 radian (~ 60~ 1 radian (~ 60OO))away from away from
PHENIXPHENIX STARSTAR
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Shock wave?Shock wave? Idea:Idea:[Casalderrey-Solana, Shuryak, Teaney: [Casalderrey-Solana, Shuryak, Teaney:
hep-ph/0411315]hep-ph/0411315](see also [Stocker: Nucl.Phys. A750 (2005) 121])(see also [Stocker: Nucl.Phys. A750 (2005) 121])
medium is densemedium is dense ““away jet” parton travels through away jet” parton travels through
medium with speed ~ cmedium with speed ~ c faster than speed of sound in faster than speed of sound in
medium: cmedium: css shock wave (“sonic boom”) is shock wave (“sonic boom”) is
emitted at angle:emitted at angle:
with cwith css22 ~ 0.2 : ~ 0.2 :
ccsarccos
)60( 1
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Baryon puzzle @ RHICBaryon puzzle @ RHIC Central Au-Au: as many Central Au-Au: as many --
(K(K--) as p () as p () at p) at pTT ~ 1.5 ~ 1.5 2.5 2.5 GeV GeV
ee++ee-- jet (SLD) jet (SLD) very few baryons very few baryons
from from fragmentation!fragmentation!
K
p
H.Huang @ SQM 2004
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if loss is partonic, shouldn’t it if loss is partonic, shouldn’t it affect p and affect p and in the same way? in the same way?
RcpRcp
central AA,
periphAA,
periph AA,
central AA,cp Yield
YieldNcoll
NcollR
strange particles come to strange particles come to rescue!rescue!
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Quark RecombinationQuark Recombination if hadrons are formed by recombination, if hadrons are formed by recombination, features of the parton features of the parton
spectrum are shifted to higher pspectrum are shifted to higher pTT in the hadron spectrum, in the hadron spectrum, in a different way for mesons and baryons in a different way for mesons and baryons constituent quark countingconstituent quark counting
s
u
s
d
u d
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S.Bass @ SQM`04
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Where should recombination Where should recombination work?work?
Proponents say @ pProponents say @ pTT between 1 and 4 GeV (6 GeV) for mesons between 1 and 4 GeV (6 GeV) for mesons (baryons)(baryons) hydro below, fragmentation above (at RHIC energy)hydro below, fragmentation above (at RHIC energy)
recombining partons:p1+p2=ph
fragmenting parton:ph = z p, z<1
R.Fries @ QM`04
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elliptic flow velliptic flow v22
Recombination also offers an explanation for the vRecombination also offers an explanation for the v22 baryon baryon puzzle...puzzle...
STAR Preliminary
scaled with n(quarks)
...)2cos(2)cos(2121
21
vvdydpp
dNdyddpp
dN
TTTT
flow"direct " cos1 v flow" elliptic" 2cos2 v
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A few hiccups...A few hiccups...
Strict recombination has a few theoretical problems...Strict recombination has a few theoretical problems... it violates 2it violates 2ndnd law of thermodynamics law of thermodynamics
reduction of the number of particles reduction of the number of particles lower disorder lower disorder entropy decreased entropy decreased
it actually also violates the 1it actually also violates the 1stst...... impossible to conserve energy and momentum simultaneouslyimpossible to conserve energy and momentum simultaneously
what happens to gluons?what happens to gluons?
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Picture emerging from RHICPicture emerging from RHIC System formed in AuAu collisionsSystem formed in AuAu collisions
presumably partonicpresumably partonic Strongly collective (~ liquid behaviour)Strongly collective (~ liquid behaviour) Very opaque medium (strong energy loss)Very opaque medium (strong energy loss) Indications for hadronization by recombinationIndications for hadronization by recombination
How can we test this scenario?How can we test this scenario? Need to confirm this picture with a different probeNeed to confirm this picture with a different probe Heavy quarksHeavy quarks
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Charm & beauty: ideal probesCharm & beauty: ideal probes calculable in pQCD; calibration measurement from ppcalculable in pQCD; calibration measurement from pp
rather solid groundrather solid ground caveat: modification of initial state effects from pp to AAcaveat: modification of initial state effects from pp to AA
shadowing ~ 30 %shadowing ~ 30 % saturation?saturation?
pA reference fundamentalpA reference fundamental!!
produced essentially in initial impactproduced essentially in initial impact probes of high density phaseprobes of high density phase
no extra production at hadronizationno extra production at hadronization probes of fragmentation probes of fragmentation
e.g.: independent string fragmentation vs recombinatione.g.: independent string fragmentation vs recombination
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Probing the mediumProbing the medium quenching vs colour chargequenching vs colour charge
heavy flavour from quark (Cheavy flavour from quark (CRR = 4/3) jets = 4/3) jets light flavour from (plight flavour from (pTT-dep) mix of quark and gluon (C-dep) mix of quark and gluon (CRR = 3) jets = 3) jets
quenching vs massquenching vs mass heavy flavour predicted to suffer less energy lossheavy flavour predicted to suffer less energy loss
gluonstrahlung: dead-cone effectgluonstrahlung: dead-cone effect beauty vs charmbeauty vs charm
heavy flavour should provide a fundamental cross-heavy flavour should provide a fundamental cross-check of quenching picture emerging from RHICcheck of quenching picture emerging from RHIC
at LHC: high stats and fully developed jetsat LHC: high stats and fully developed jets
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Heavy flavour production in AAHeavy flavour production in AA binary scaling: binary scaling:
can be broken by:can be broken by: initial state effects (modified PDFs)initial state effects (modified PDFs)
shadowingshadowing kkTT broadening broadening gluon saturation (colour glass)gluon saturation (colour glass)
(concentrated at lower p(concentrated at lower pTT))
final state effectsfinal state effects (modified fragmentation) (modified fragmentation) parton energy lossparton energy loss violations of independent fragmentation (e.g. quark recombination) violations of independent fragmentation (e.g. quark recombination)
(at higher p(at higher pTT))
ppAA dcollNd
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Heavy flavour energy loss?Heavy flavour energy loss?
Energy loss for heavy flavours is expected to be reduced:Energy loss for heavy flavours is expected to be reduced:i)i) Casimir factorCasimir factor
light hadrons originate predominantly from gluon jets, light hadrons originate predominantly from gluon jets, heavy flavoured hadrons originate from heavy quark jets heavy flavoured hadrons originate from heavy quark jets
CCRR is 4/3 for quarks, 3 for gluons is 4/3 for quarks, 3 for gluons ii)ii) dead-cone effectdead-cone effect
gluon radiation expected to be suppressed for gluon radiation expected to be suppressed for < M < MQQ/E/EQQ[Dokshitzer & Karzeev,[Dokshitzer & Karzeev, Phys. Lett. Phys. Lett. B519B519 (2001) 199] (2001) 199][Armesto et al., Phys. Rev. D69 (2004) 114003][Armesto et al., Phys. Rev. D69 (2004) 114003]
2 ˆ LqCE Rs
Casimir coupling factortransport coefficient of the medium
average energy loss distance travelled in the medium
R.Baier et al., Nucl. Phys. B483 (1997) 291 (“BDMPS”)
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Large suppression at RHIC!Large suppression at RHIC! yet, region above 3-4 GeV yet, region above 3-4 GeV
expected to be dominated expected to be dominated by beauty...by beauty...
[Xin Dong@QM05]
n.p. electrons ~ as suppressed as n.p. electrons ~ as suppressed as expected for c only (no b)expected for c only (no b)
scaled to
M. Cacciari et al., hep-ph/0502203
[J.Bielcik @QM05] disentangling c/b is a mustdisentangling c/b is a must!! e.g. full reconstruction of D verticese.g. full reconstruction of D vertices
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||<0.9:B = 0.4 TTOFTPCITS with: - Si pixels- Si drifts- Si strips
PIXEL CELL
z: 425 m
r: 50 m
Two layers:r = 4 cmr = 7 cm
9.8 M
ALICEALICE
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Track Impact ParameterTrack Impact Parameter
expected dexpected d00 resolution resolution (() )
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LHC is a Heavy Flavour Machine!LHC is a Heavy Flavour Machine! cccc and and bbbb rates rates
ALICE PPR (NTLO + shadowing)ALICE PPR (NTLO + shadowing)
115 115 // 4.64.60.65 0.65 // 0.850.856.6 6.6 // 0.20.2Pb-Pb 5.5 TeV (5% cent)Pb-Pb 5.5 TeV (5% cent)0.160.16 // 0.0070.00711 // 1111.211.2 // 0.50.5 pp 14 TeVpp 14 TeV
shadowingshadowingsystemsystem NN x-sect (mb)NN x-sect (mb) total multiplicitytotal multiplicity
PbPbpp
PbPbpp
cc bbPbPb/pp PbPb/pp
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some prediction ...some prediction ...T
BDpp
TBD
AA
collT
BDAA dpdN
dpdNN
pR//1)( ,
,,
[Armesto et al.: Phys.Rev. D71 (2005) 054027]
charm beauty
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DD00 K K--++
expected ALICE expected ALICE performance performance S/B ≈ 10 %S/B ≈ 10 % S/S/(S+B) ≈ 40 (S+B) ≈ 40
(1 month Pb-Pb running)(1 month Pb-Pb running)
statistical.
systematic.
ppTT - differential - differential similar performance in ppsimilar performance in pp
(wider primary vertex spread)(wider primary vertex spread)
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RRAAAA(D) in ALICE(D) in ALICE
Low pT (< 6–7 GeV/c)Nuclear shadowing ‘High’ pT (6–15 GeV/c)
expected performance (1 month Pb-Pb, 9 months expected performance (1 month Pb-Pb, 9 months p-p)p-p)
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B B e e±± + X + X Expected ALICE performance (1 month Pb-Pb)Expected ALICE performance (1 month Pb-Pb)
ee±± identification from TRD and dE/dx in TPC identification from TRD and dE/dx in TPC impact parameter from ITSimpact parameter from ITS
pt > 2 GeV/c , 200 < |d0| < 600 m 80% purity8 104 e from B
pt > 2 GeV/c , 200 < |d0| < 600 m 80% purity8 104 e from B
S/(S+B)S/(S+B) S per 10S per 1077 central Pb-Pb events central Pb-Pb events
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At LHC: At LHC: realreal jets! jets! 2 GeV 20 GeV 100 GeV 200 GeV
Mini-Jets 100/event 1/event 100k/month Well visible event-by-event! e.g. 100 GeV jet + underlying event:Well visible event-by-event! e.g. 100 GeV jet + underlying event:
e.g.: study quenching with b-tagged jets!e.g.: study quenching with b-tagged jets!
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b taggingb tagging e.g.: ATLAS u rejection (Re.g.: ATLAS u rejection (Ruu) performance in Pb-Pb) performance in Pb-Pb
H H bb, uu with M bb, uu with MHH = 400 GeV = 400 GeV
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Away side?Away side? Collective behaviour opposite to Collective behaviour opposite to
jetjet eg: Mach cone eg: Mach cone
[Casalderrey-Solana, et al.: hep-ph/0411315][Casalderrey-Solana, et al.: hep-ph/0411315][Stocker: Nucl.Phys. A750 (2005) 121])[Stocker: Nucl.Phys. A750 (2005) 121])
What happens with big-fat-heavy-quark jets?What happens with big-fat-heavy-quark jets? e.g.: modification of Mach cone? e.g.: modification of Mach cone? [FA, E Shuryak: J.Phys. G31 (2005) 19][FA, E Shuryak: J.Phys. G31 (2005) 19]
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Machine commissioning scenarioMachine commissioning scenario (as envisaged today)(as envisaged today)
T0T0 (= 1st of July 2007 as of today) (= 1st of July 2007 as of today) One monthOne month to get the machine ready for beams ( to get the machine ready for beams (T0 + 1 monthT0 + 1 month)) Three monthsThree months to commission the machine with beams ( to commission the machine with beams (T0 + 4 T0 + 4
monthsmonths)) One monthOne month of rather stable operations, interleaved with machine of rather stable operations, interleaved with machine
development with 43 and 156 bunches, with the possibility of development with 43 and 156 bunches, with the possibility of collisions for physics during nights (~ 20 shifts of 10 hours each L ~ collisions for physics during nights (~ 20 shifts of 10 hours each L ~ 1to 3.5x101to 3.5x103030cmcm–2–2ss–1–1) () (T0 + 5 monthsT0 + 5 months))
Shutdown (Shutdown (T0 + 8 to 9 monthsT0 + 8 to 9 months): today machine people talk about 3 ): today machine people talk about 3 to 4 months. It will depend on requirements by experiments. to 4 months. It will depend on requirements by experiments. If T0 = 1st of July, start of shutdown will coincide with the Christmas If T0 = 1st of July, start of shutdown will coincide with the Christmas holidays!holidays!
July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar
Shutdown 3 to 4 months?Stable beamsPreparation
“first minutes” of data
…First collisions…….
T0 first large data sample
first Pb-Pb collisions in 2008
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Example: B in ppExample: B in pp B B e + X e + X
electron id in TRD and TPC, electron impact parameter from ITSelectron id in TRD and TPC, electron impact parameter from ITS
Expected stats from “first large pp sample” in ALICE ~ a few 10Expected stats from “first large pp sample” in ALICE ~ a few 1077 evts evtsCarlo Bombonati
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ConclusioniConclusioni StatoStato: il campo è più vivo che mai: il campo è più vivo che mai
SPS: osservazione delle “signatures” storicheSPS: osservazione delle “signatures” storiche RHIC: comportamento idrodinamico? forte attenuazione dei RHIC: comportamento idrodinamico? forte attenuazione dei
jet?jet?
ProspettiveProspettive: l’LHC è una macchina ideale per AA: l’LHC è una macchina ideale per AA altissima energia -> “deep deconfinement”altissima energia -> “deep deconfinement” alte rate di hard probesalte rate di hard probes un esperimento dedicato (ALICE), buone performance in altri un esperimento dedicato (ALICE), buone performance in altri
due (ATLAS, CMS)due (ATLAS, CMS)
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Lattice QCDLattice QCD
zero baryon density, 3 zero baryon density, 3 flavoursflavours
changes rapidly around changes rapidly around TTcc
TTcc = 170 MeV: = 170 MeV: cc = 0.6 GeV/fm = 0.6 GeV/fm33
at at TT~1.2 ~1.2 TTcc settles at settles at about 80% of the Stefan-about 80% of the Stefan-Boltzmann value for an Boltzmann value for an ideal gas of q,q g (ideal gas of q,q g (SBSB))
3 flavours; (q-q)=0
In lattice QCD, non-perturbative problems are treated by discretization on a space-time lattice