May 19, 2001May 19, 2001. Pablo Yepes, Rice U 1 HI CMS Heavy Ion Physics Pablo Yepes Rice University Hadronic Collisions Quarkonia Production Jet Collisions Coherent Interactions
CMS Heavy Ion Physics
Mar 19, 2016
CMS Heavy Ion Physics. Pablo Yepes Rice University. Hadronic Collisions Quarkonia Production Jet Collisions Coherent Interactions. Why HI at LHC Jurgen Shukraft, Quark Matter 2001. Before. Pb. Pb. Pb+Pb, central collisions (b=0). After. J/ Y Melting. p -. J / Y. c c. Hadron - PowerPoint PPT Presentation
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May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 1
HI
CMS Heavy Ion PhysicsPablo Yepes
Rice University
Hadronic CollisionsQuarkonia ProductionJet Collisions
Coherent Interactions
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 2
HIWhy HI at LHCJurgen Shukraft, Quark Matter 2001
SPS RHIC LHC
dNch/dy 500 800 3000Vf(Kfm3) 1 7 20 Bigger(GeV/fm3) 2.5 5 20 HotterQGP(fm/c) 1 3 7 Longer0(fm/c) 1 0.5 0.2
Pb+Pb, central collisions (b=0)
Pb Pb
Before
After
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 3
HIJ/Melting
L(fm): Average distance travel by the J/ inside tNuclear Matter.
J/
Yie
ld
u,d u,d
c c Hadrongas
J/K+
-
u,d u,d
c cQGP
ud
d
NA50 Collaboration, CERN
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 4
HIQuarkonia Acceptance in CMS Chambers
10%
20%
Acc
epta
nce
J/at CMS
Upsilon at CMSPt(GeV)
Full Detector
Full Detector
Barrel
Barrel
•CMS: J/ mainly pT>5 GeV with barrel, due to cutoff. •ALICE: >2.5 with •ATLAS (if they do HI) lower acceptance due to higher pT cutoff.
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 5
HI Quarkonia Reconstruction Essential sub-detectors:
Tracking devices Muon system
Pessimistic assumptions for background estimates:dNch/dy=8000
(most generators < 5500)<pt>GeV/c (HIJING
0.39 GeV/c)<pt>k=0.67 GeV/c
Special Heavy Ion Tracking AlgorithmSignificant Muon background from and K decays
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 6
HIJ/ Signal 1 month running at top Luminosity: J/’s detected and reconstructed in the Barrel:
Ca-Ca Pb-Pb
# J/ 2.2 105 104
S/B 9.7 1.010 3
10 4
2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5
Min bias collisions - 1 month run - barrel onlymuons with P > 3.5 GeV/c
Pb-Pb
/cont.= 1.0
# ev
ents
/25
MeV
/c2
10 4
10 5
2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5
Ca-Ca
/cont.= 9.7
Opposite-sign di-muon invariant mass (GeV/c2)
L= 2.5 1029 cm2 s-1
# ev
ents
/25
MeV
/c2
L= 1027 cm2 s-1
ALICE: ~2K events with s
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 7
HI
1 month: 22000 and 7500 ’ detected in the barrel
Upsilon in Pb-Pb
Opposite-sign di-muon Invariant Mass (GeV/c2)Background contributions
1022
1033
104
8.5 8.75 9 9.25 9.5 9.75 10 10.25 10.5 10.75 11
L= 1027 cm-2 s-1
Total
Decay-Decay Decay-b
Decay-c
b-b
c-c
Upsilon/cont.= 1.6
# E
vent
s/25
MeV
/c2
0
1000
2000
3000
4000
5000
6000
7000
8.5 8.75 9 9.25 9.5 9.75 10 10.25 10.5 10.75 11
Di-muon Invariant Mass (GeV/c2)
# E
vent
s/25
MeV
/c2
Combinatorial background subtracted after reconstruction
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 8
HIUpsilon in Ca-Ca
103
104
105
8.5 8.75 9 9.25 9.5 9.75 10 10.25 10.5 10.75 11
Opposite-sign di-muon invariant mass (GeV/c2)
L= 2.5 1029 cm-2s-1
Total
Decay-Decay
Decay-b
Decay-c
b-b
Upsilon/cont.= 9.4
# E
vent
s/25
MeV
/c2
• 1 month: • 340000 • 115000 ’
• Only barrel used.
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 9
HI
Upsilon’/Upsilon ratio as a
Thermometer(Ramona Vogt)
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 10
HIQuarkonia Reference At SPS, J/ is compared to
Drell-Yan. At LHC Drell-Yan
contribution is negligible. Z0 proposed as reference to
production.MZ>M
Different production mechanisms: Z0: antiquark-quark, quark-gluon and
antiquark-gluon. : gluon-gluon.
Cross check di-muon reconstruction algorithm
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 11
HIJet Quenching• Large pT quarks affected by hot hadronic media• Jets at RHIC buried in low pT background• Look at particle pt spectrum
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 12
HIJets at LHC are Easy for High Multiplicity PbPb
monojet/dijet enhancement jet-Z0or jet-
dNch/dy=8000
Tota
l Cal
orim
eter
Ene
rgy
Jet Finding100 GeV ET
-~100%- (ET)/ET=11.6%.
Jet quenching
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 13
HIBalancing Photons and Jets Et
jet,
120GeV in the barrel
1 month:900 events
for Pb-Pb104 events
for Ca-Ca
# E
vent
s/4
GeV
ET//0-ET
Jet (GeV)
<E>=8 GeV<E>=4 GeV<E>=0 GeV
Background
2 weeks at L=1027 cm-2s-
1
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 14
HIUltra Peripheral Collisions(Coherent Interactions)
Low pT pT < 1/R 50 MeV Low Energy ECM
Max < /R CERN SPS ECM
Max =0.5 GeV RHIC ECM
Max =6 GeV Detected CERN LHC ECM
Max =160 GeV
A
A orP
orP
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 15
HISTAR Ultra-Peripheral Event
(DNP 2000)
End view
AuAuP (Au)
Trigger: Low multiplicity and zero energy at Zero Degree Calorimeter (ZDC)
Side view
ZDC ZDC
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 16
HI Physics
New Physics:Standard Model H production marginal for HIAny exotic particle coupling to . Supersymmetric Higgs for some areas of parameters space.
Mainly studied at e+e- colliders.Typically 0<mc. tot up to 70 GeV by LEP.
Non perturbative QED, coupling Z2.
Ethr(GeV)
(Pb+Pb)(barn)
(Ca+Ca)(barn)
0.5 1,500 5.51.0 500 1.85.0 30 0.1
e+e- Cross Sections
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 17
HI
even
ts/s
ec/G
eV
10-14
10-12
10-10
10-8
10-6
10-4
10-2
100
10-1 100 10 102 10-12
10-10
10-8
10-6
10-4
10-2
10
102
AA
(bar
n)
even
ts/s
ec
M (GeV)
f2
a2f2'
cccc0cc2
b
0bb
HSM
H'
10-5
10-3
10-1
10
103
105
107
even
ts/y
ear
1 10 102
M (GeV)1014
1012
1010
108
106
104
102
1
10-12
10-10
10-8
10-6
10-4
10-2
1
102
AA(M
) (ba
rn/G
eV)
hadrons
e+e-
cc
bb
10-5
10-3
10-1
10
103
105
107
even
ts/y
ear/
GeV
Ultra-Peripheral Collisions Cross Sections
Meson orlepton/quark pair
A
AA
A
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 18
HI Physics, Hadron Spectroscopy
Heavy quark spectroscopy. Very large numbers expected
Light quark: Difficult at CMS because of low pT, challenge for triggering, unless a multiplicity trigger is used.
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 19
HIPhoton Nucleus (A)
p studied in HERA: Wp<200 GeV A at LHC: Wp<900 GeV Vector meson production: p(A) Vp(A),
V=,J/Very large rates, for example >104 Hz in Ca-CaInterface QCD and hadronic physicsLHC will be a meson factory. Competitive with other meson
factories like factory at Frascatti (CP, QM tests, etc).Can CMS trigger on these events. Clean events with only a
few tracks.
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 20
HIConclusions
CMS is provides unique tools to study Heavy Ion Collisions at LHC.
Some physics topics:Quarkonium production: and J/ families.Jet quenching. Ultra-Peripheral collisions.
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 21
HIAddendum: Tracking
Developed for dNch/dy=8000 and dN0/dy=4000.
Track only particles with tracks in detector.
Use -chambers tracks as seeds.
Use only tracking detector providing 3D space points.
Occ
upan
cy (%
)
0
10
20
30
40
50
60
60 70 80 90 100 110 120
Detector Pitch m MSGC 200 MSGC 240 Silicon 147
Radius of MSGC layer (cm)
May 19, 2001May 19, 2001.
Pablo Yepes, Rice U 22
HIInterference
Nuclei can emit or scatter pairtwo indistinguishable possibilities
Amplitudes addVector meson has negative parity
~ |A1 - A2eip·b|2
Destructive interference when pT << 1/b
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