Future plan of dilepton measurement
レプトン対測定の将来計画
Satoshi Yano
Hiroshima University
Heavy Ion Pub @ Kyoto
03/08/2022

Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production2

Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production

3

Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production

4

Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production

5Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production

6

Dilepton measurement in HIC•– Carry the information w/o final-state interactions

IMR

LMR
π0, η, ρ•ω, φDilepton: dielectron (e+e-) and dimuon (μ+μ-)

Dilepton is interesting because of its invariant mass info.
– Low mass region (LMR): Mll < 1.0 GeV/c2– Vector meson mass modification induced by medium effects– Thermal radiation at a late stage

HG– Intermediate mass region (IMR): 1.0 < Mll < 2.5 GeV/c2– Yield enhancement induced by chiral mixing– Thermal radiation at an early stage– High mass region (HMR): Mll > 2.5 GeV/c2– Quakonia + beauty quark pair production

7

Experimental techniqueelectron identification•

All techniques use mass information for identification–•

e.g. dE/dx, time-of-flight, and so on

Unfortunately, muon mass is almost the same as the pion mass
– μ=105MeV/c2, π=139MeV/c28Experimental techniqueelectron identification•

All techniques use mass information for identification–•

e.g. dE/dx, time-of-flight, and so on

Unfortunately, muon mass is almost the same as the pion mass
– μ=105MeV/c2, π=139MeV/c2

9Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electron•

Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

10Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electron

Material Detector•

Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

11

Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electronμ•Material Detector

Penetrate (achieving a detector)

Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

12Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electronμMaterial Detectorh•Penetrate (achieving a detector)
Stopped by the hadron shower

Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

13

Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electronμMaterial Detector

h
e/γ

•

Penetrate (achieving a detector)
Stopped by the hadron shower
Stopped by the EM shower

Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

14

Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electronμMaterial Detectorhe/γ
Low-p μ•Penetrate (achieving a detector)
Stopped by the hadron shower
Stopped by the EM shower
Stopped by multiple scattering (elastic scattering)Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT

15

Experimental technique
Muon identification•

Muon penetrates thick material easily– Stable lepton with much higher mass than electron

Material DetectorμhStopped by the hadron showere/γ

Stopped by the EM shower

Low-p μ•Penetrate (achieving a detector)

Stopped by multiple scattering (elastic scattering)Low-pT muon is measured in forward rapidity (Lab-frame)– Satisfy large total momentum and low-pT
p
m
u
t
n
e
m
o
tal m

PV

To

Beam axis

Transverse
momentum pTe.g. p~5GeV/c → pT~0.5GeV/c @ η=3.0

16

1990s - 2010s17

Results from SPS: CERES
dielectron measurement•

CERES collaboration observed the enhancement in LMR in A-A collisions, not in pp via dielectron– Low mass vector meson mass modification due to Chiral symmetry restoration (CSR)?
– Dropping? or Broadening?

•

Resolution and statistics accuracy was insufficient to determine the source0
Combinatorial
background electrons
PH YS–ICALREVIEW LETTERS
14 AUGUsTfrom
1995 π Dalitz decay and γ conversion were hugeermined by the number
5 is then extracted byn from the e e sam-

—

v

~ 10

4

p-Be 450 GeVp&) 50 MeV/c

0 ) 35 rnradz.

) e+e,

0.2 GeV/c

consistse
resulting in a
a S/B ratio of 1/4. 3,(p-Au) sample a signal
s is obtained at a S/B

the expected sources
ays. For pair massesz decay dominates thesses the decays
e+e should be theated the invariant-mass
ng all known hadronicu, and P. The particle
rces are assumed to be
em and to scale with

~

~10
c 10

Excess!

Described by known source

-6

~ 10
10

10

-9

0

FIG. 2. Inclusive

0.2

0.4

e+ e

0.6

0.8

1

1.2
1.4
m (GeV/c )mass spectra in 450 GeV p-Be
collisions showing the data (full circles) and the various
contributions from hadron decays. The shaded region indicates

18

428

CERES Collaboration / Physics Letters B 666 (2008) 425–429

Results from SPS: CERES
dielectron measurement•

CERES collaboration observed the enhancement in LMR in A-A collisions, not in pp via dielectron– Low mass vector meson mass modification due to Chiral symmetry restoration (CSR)?
– Dropping? or Broadening?

•

Resolution and statistics accuracy was insufficient to determine the source0
Combinatorial
background electrons
PH YS–ICALREVIEW LETTERS
14 AUGUsTfrom
1995 π Dalitz decay and γ conversion were huge

Fig. 2. (a) Invariant e + e − mass spectrum compared to the expectation from hadronic decays. (b) The same data compa(dashed) and a broadened ρ -spectral function (long-dashed). Systematic errors are indicated by horizontal ticks.

ermined by the number
5 is then extracted byn from the e e sam-

—

v

~ 10

4

p-Be 450 GeVp&) 50 MeV/c

0 ) 35 rnradz.

) e+e,

0.2 GeV/c

consistse
resulting in a
a S/B ratio of 1/4. 3,(p-Au) sample a signal
s is obtained at a S/B

the expected sources
ays. For pair massesz decay dominates thesses the decays
e+e should be theated the invariant-mass
ng all known hadronicu, and P. The particle
rces are assumed to be
em and to scale with

~

~10
c 10

Excess!

Described by known source

-6

~ 10
10

10

-9

0

FIG. 2. Inclusive

0.2

0.4

e+ e

0.6

0.8

1

1.2
1.4
m (GeV/c )mass spectra in 450 GeV p-Be
collisions showing the data (full circles) and the various
contributions from hadron decays. The shaded region indicates

19

Fig. 3. e + e − pair yield after subtraction of the hadronic cocktail. In addition to the statistical error bars, systematic errors
uncertainty of the subtracted cocktail (shaded boxes) are indicated. The broadening scenario (long-dashed line) is compare
dropping ρ mass (dotted line in (a)) and to a broadening scenario excluding baryon effects (dotted line in (b)).

Results from SPS: NA60
dimuon measurement•

Clear excess was observed with high-quality data
– Ruled out the dropping mass
• Underestimate 0.6 - 0.8 GeV/c2, overestimate 0.2 - 0.6 GeV/c2– Excess data in LMR could be described by the hadronic matter effect• Not include the CSR effect•

Excess data at IMR was explained by thermal radiation– qqbar→μμ20

Results from SPS: NA60
dimuon measurement•

Clear excess was observed with high-quality data
– Ruled out the dropping mass
• Underestimate 0.6 - 0.8 GeV/c2, overestimate 0.2 - 0.6 GeV/c2– Excess data in LMR could be described by the hadronic matter effect• Not include the CSR effect

Excess data at IMR was explained by thermal radiation– qqbar→μμ
semicentral In-In
all qT
Tc=Tch=175 MeV

NA60
in-med ρ
QGP+DD
prim ρ
FO + in-med ρ
4π mix
DY
sum

1500

1000

1/qT dNµµ/(dqT dy) (counts)

2000

dNµµ/dM (counts)

•

500

10

8

10

7

10

6

10

5

10

4

10

3

10
0
1000

0.2

0.4

semicentral In-In

0.6

0.8
M (GeV)

1

1.2
NA60

2

semicentral In-In
0.4 GeV<M<0.6 GeV

NA60
total
in-med ρ
QGP
DY
FO+prim ρ
0.5

1.4

10

Tc=Tch=175 MeV
1qT (GeV)

1.5

8

semicentral In-In

2

21

Results from SPS: NA60
dimuon measurement•

Teff = T0 + m < β >2

Clear excess was observed with high-quality data
– Ruled out the dropping mass
• Underestimate 0.6 - 0.8 GeV/c2, overestimate 0.2 - 0.6 GeV/c2– Excess data in LMR could be described by the hadronic matter effect• Not include the CSR effect

Excess data at IMR was explained by thermal radiation– qqbar→μμ
semicentral In-In
all qT
Tc=Tch=175 MeV• Excess below 1 GeV/c

NA60
in-med ρ
QGP+DD
prim ρ
FO + in-med ρ
4π mix
DY
sum

1500

1000

1/qT dNµµ/(dqT dy) (counts)

2000

dNµµ/dM (counts)

•

10

8

10

7

semicentral In-In
2
0.4 GeV<M<0.6 GeV– 6 Consistent with other hadrons
10–105 Late-stage emission after the occurrence of radial flow

NA60 above 1 GeV/c2
10• Excess
total
500

4

1000

0.2

0.4

semicentral In-In

0.6

0.8
M (GeV)

1

1.2
NA60

1.4

3
2

– Early-stage
emission
beforethe2 occurrence of radial flow
0.5
1
1.5
10

0

in-med ρ
QGP
DY
FO+prim ρ– No mass dependence
Tc=Tch=175 MeV
10qT (GeV)
108semicentral In-In

22

RHIC results
dielectron measurement•

Multiple verifications suggest QGP is generated at RHIC energies•

The same trend as SPS was seen in the collision energy of the RHIC BES program– Same temperature in LMR = the same temperature at late stage– Higher temperature in IMR = higher temperature at early stage•

Enhancement has been measured at top energy sNN = 200 GeV (MB: 2.4M Evts)– Large uncertainties due to the huge combinatorics @ LMR and HF contributions @ IMR

23

RHIC results
dielectron measurement•

Multiple verifications suggest QGP is generated at RHIC energies•

The same trend as SPS was seen in the collision energy of the RHIC BES program– Same temperature in LMR = the same temperature at late stage– Higher temperature in IMR = higher temperature at early stage•

Enhancement has been measured at top energy sNN = 200 GeV (MB: 2.4M Evts)– Large uncertainties due to the huge combinatorics @ LMR and HF contributions @ IMR

Beam Enegy Scan between SPS and top RHIC

24

RHIC results
dielectron measurement•

Multiple verifications suggest QGP is generated at RHIC energies•

The same trend as SPS was seen in the collision energy of the RHIC BES program– Same temperature in LMR = the same temperature at late stage– Higher temperature in IMR = higher temperature at early stage•

Enhancement has been measured at top energy sNN = 200 GeV (MB: 2.4M Evts)– Large uncertainties due to the huge combinatorics @ LMR and HF contributions @ IMR

Beam Enegy Scan between SPS and top RHIC

25

RHIC results
dielectron measurement•

Multiple verifications suggest QGP is generated at RHIC energies•

The same trend as SPS was seen in the collision energy of the RHIC BES program– Same temperature in LMR = the same temperature at late stage– Higher temperature in IMR = higher temperature at early stage•

Enhancement has been measured at top energy sNN = 200 GeV (MB: 2.4M Evts)– Large uncertainties due to the huge combinatorics @ LMR and HF contributions @ IMR

Beam Enegy Scan between SPS and top RHIC

Top RHIC energy √sNN = 200 GeV (MB)26

Dielectron spectrum seems to have enhancement at LMR (0-10%:
65M Evts)– No conclusion due to insufficient accuracy•

ALICE Preliminary
0−10% Pb−Pb at sNN = 5.02 TeV
0.2 < p < 10 GeV/c , |ηe| < 0.8T,e< 8.0 GeV/c
0.0 < p

102

10

T,ee

Data
Cocktail sum (POWHEG × <N coll>)
c/b → eCocktail sum (POWHEG × <N coll> × R AA )Light flavor → e+e−, e+e− X
J/ ψ → e+e−, e+e− γ
cc → e+e− (POWHEG × <N coll>)
bb → e+e− (POWHEG × <N coll>)
c/b → ecc → e+e− (POWHEG × <N coll> × R AA )c/b → ebb → e+e− (POWHEG × <N coll> × R AA )10−1

It is difficult to extract thermal dielectron at IMR– More contribution from HF w.r.t. the previous experiments

Dielectron spectrum
1

10−2

10−3

ratio to cocktail ratio to cocktail•

1 dN (GeV/ c 2)−1
N ev dm ee

LHC results
Dielectron and dimuon measurement

3
2.5
2
1.5
1
0.5

cocktail + QGP + in-medium ρ (R.Rapp, Adv. HEP. 2013 (2013) 148253)
cocktail + QGP + in-medium ρ (PHSD, PRC 97 (2018) 064907)

3
2.5
2
1.5
1
0.5
0

ALI−PREL−507155

0.5

1

1.5

2

2.5

3
3.5
m ee (GeV/ c 2)

27

0.8

Centrality: 0 % - 90 %

0.6
0.4
0.2
0

4

6

ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 4

0.8

1ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 4

0.8

Centrality: 0 % - 10 %

0.6

0.6

0.4

0.4

0.2

0.2

0

8
10
p (GeV/ c )

2

4

6

Centrality: 0 % - 20 %0810p (GeV/ c )

2

4

6

65M Evts)
ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 4

0.8

Centrality: 20 % - 40 %

0.6

T

1

ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 40.81A*ε (ϕ)1

T

ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 4

0.8

Centrality: 40 % - 60 %0.6

Centrality: 60 % - 90 %0.6

– No conclusion due to insufficient accuracy
0.4

4

6

0

8
10
p (GeV/ c )

0.2

2

4

6

0

8
10
p (GeV/ c )

2

4

6

T

φ→µµ

ω →µµ

Pb-Pb sNN = 5.02 TeVCentrality range: 0-90%
2.5 < y < 4
2 < p < 7 GeV/ c

w/o trigger threshold

η→ µµ
γ
cc

ω→µ

µπ 0 ρ→ µµ
η’→µµγ

0.5

5000

1.5

2

0

Fig. 23: Dimuon invariant mass spectrum in Pb–Pb collisions at

0.5

bb

1.5

2

2.5

3
3.5
m ee (GeV/ c 2)

1

1.5

2

– down to pT~0.5 GeV/c w/o trigger threshold– Inaccessible estimation of HF contribution

M µµ (GeV/c 2)√

1– Inaccessible low pT region due to trigger operation

ω→ µµ 0 ρ→ µµπ
η’→µµγM µµ (GeV/c 2)

0.5– Insufficient mass resolution due to multiple scattering
cc

bb

1

3
2.5
2
1.5
1
0.5

• Dimuon spectrum cannot access LMR and IMRγ

5000

cocktail + QGP + in-medium ρ (R.Rapp, Adv. HEP. 2013 (2013) 148253)
cocktail + QGP + in-medium ρ (PHSD, PRC 97 (2018) 064907)

ALI−PREL−507155

10000

10000

3
2.5
2
1.5
1
0.5

0

T

15000

15000

0

dN/dM µµ (dimuons per 50 MeV/c 2)

φ→µµ

ω →µµ

T

20000

µ
η→µ

dN/dM µµ (dimuons per 50 MeV/c 2)

Pb-Pb sNN = 5.02 TeVCentrality range: 0-90%
2.5 < y < 4
2 < p < 7 GeV/ c

10−3

T

T

Dimuon spectrum

10−2

8
10
p (GeV/ c )– More contribution from HF w.r.t. the previous experiments
Fig. 22: A × ε as a function of p for several centralities.
T

20000

T,ee

Data
Cocktail sum (POWHEG × <N coll>)
c/b → eCocktail sum (POWHEG × <N coll> × R AA )Light flavor → e+e−, e+e− X
J/ ψ → e+e−, e+e− γ
cc → e+e− (POWHEG × <N coll>)
bb → e+e− (POWHEG × <N coll>)
c/b → ecc → e+e− (POWHEG × <N coll> × R AA )c/b → ebb → e+e− (POWHEG × <N coll> × R AA )10−1

It is difficult to extract thermal dielectron at IMR
2

10

0.4

0.2

0

ALICE Preliminary
0−10% Pb−Pb at sNN = 5.02 TeV
0.2 < p < 10 GeV/c , |ηe| < 0.8T,e< 8.0 GeV/c
0.0 < p102

1

ratio to cocktail ratio to cocktail

•

0.4

0.2

Dielectron spectrum

810p (GeV/ c )Dielectron spectrum seems to have enhancement at LMR (0-10%:T

A*ε (ϕ)A*ε (ϕ)•2

1

1 dN (GeV/ c 2)−1
N ev dm ee

ALICE Pb-Pb s = 5.02 TeV
2.5 < y < 4A*ε (ϕ)A*ε (ϕ)A*ε (ϕ)LHC results
Dielectron and dimuon measurement1

s = 5.02 TeV after combinatorial background28

bb → e e− (POWHEG × <N coll> × R AA

)

10−1

Focus on LMR results at RHIC and LHC
10−2

10−3

Top LHC energy √sNN = 5.02 TeV (0-10%)
ratio to cocktail ratio to cocktail

Top RHIC energy √sNN = 200 GeV (MB)
3
2.5
2
1.5
1
0.5

cocktail + QGP + in-medium ρ (R.Rapp, Adv. HEP. 2013 (2013) 148253)
cocktail + QGP + in-medium ρ (PHSD, PRC 97 (2018) 064907)

3
2.5
2
1.5
1
0.5
0

0.5

1

ALI−PREL−507155

•

1.5

2

2.5

3
3.5
m ee (GeV/ c 2)

Collisional broadening seems to overestimate both data in a mass range of 0.6 - 0.8 GeV/c2– Need more precise measurement•

Thermal dilepton cannot be accessed due to huge HF contributions•

Much more statistics, reduction of combinatorics, and HF lepton rejection are necesary29

bb → e e− (POWHEG × <N coll> × R AA

)

10−1

Focus on LMR results at RHIC and LHC
10−2

10−3

Top LHC energy √sNN = 5.02 TeV (0-10%)
ratio to cocktail ratio to cocktail

Top RHIC energy √sNN = 200 GeV (MB)
3
2.5
2
1.5
1
0.5

cocktail + QGP + in-medium ρ (R.Rapp, Adv. HEP. 2013 (2013) 148253)
cocktail + QGP + in-medium ρ (PHSD, PRC 97 (2018) 064907)

3
2.5
2
1.5
1
0.5
0

0.5

1

ALI−PREL−507155

•

1.5

2

2.5

3
3.5
m ee (GeV/ c 2)

Collisional broadening seems to overestimate both data in a mass range of 0.6 - 0.8 GeV/c2– Need more precise measurement•

Thermal dilepton cannot be accessed due to huge HF contributions•

Much more statistics, reduction of combinatorics, and HF lepton rejection are necesary

30

bb → e e− (POWHEG × <N coll> × R AA

)

10−1

Focus on LMR results at RHIC and LHC
10−2

10−3

Top LHC energy √sNN = 5.02 TeV (0-10%)
ratio to cocktail ratio to cocktail

Top RHIC energy √sNN = 200 GeV (MB)
3
2.5
2
1.5
1
0.5

cocktail + QGP + in-medium ρ (R.Rapp, Adv. HEP. 2013 (2013) 148253)
cocktail + QGP + in-medium ρ (PHSD, PRC 97 (2018) 064907)

3
2.5
2
1.5
1
0.5
0

0.5

1

ALI−PREL−507155

•

1.5

2

2.5

3
3.5
m ee (GeV/ c 2)

Collisional broadening seems to overestimate both data in a mass range of 0.6 - 0.8 GeV/c2– Need more precise measurement•

Thermal dilepton cannot be accessed due to huge HF contributions•

Much more statistics, reduction of combinatorics, and HF lepton rejection are necesary31What learned?
•

At SPS and RHIC BES energy ( sNN ~ 17 - 55 GeV), the LMR excess (broadening) could be explained byhadronic matter effects– Mass modification at LMR was discovered, but it did not indicate CSR necessarily• Ruled out mass dropping scenario at these energies– Thermal dilepton was measured and they are above Tc ~ 170 MeV– Chiral mixing signal did not been measured•

At RHIC and LHC energy ( sNN ~ 200 GeV - 5 TeV), larger signals has been expected, but the huge
combinatorial background and HF contributions disturbed the measurements– Excess at LMR with insufficient precision has been measured– Hadronic matter effects overestimate in a mass range of 0.6 - 0.8 GeV/c2 (?)•

Improvement of detection technology/method is essential– Improvement of vertex detector to determine leptons from HF DCA at low pT– Reconfirmation of dimuon measurement at LHC energy

32What learned?
•

At SPS and RHIC BES energy ( sNN ~ 17 - 55 GeV), the LMR excess (broadening) could be explained byhadronic matter effects– Mass modification at LMR was discovered, but it did not indicate CSR necessarily• Ruled out mass dropping scenario at these energies– Thermal dilepton was measured and they are above Tc ~ 170 MeV– Chiral mixing signal did not been measured•

At RHIC and LHC energy ( sNN ~ 200 GeV - 5 TeV), larger signals has been expected, but the huge
combinatorial background and HF contributions disturbed the measurements– Excess at LMR with insufficient precision has been measured– Hadronic matter effects overestimate in a mass range of 0.6 - 0.8 GeV/c2 (?)•

Improvement of detection technology/method is essential– Improvement of vertex detector to determine leptons from HF DCA at low pT– Reconfirmation of dimuon measurement at LHC energy

33

What learned?
•

At SPS and RHIC BES energy ( sNN ~ 17 - 55 GeV), the LMR excess (broadening) could be explained byhadronic matter effects– Mass modification at LMR was discovered, but it did not indicate CSR necessarily• Ruled out mass dropping scenario at these energies– Thermal dilepton was measured and they are above Tc ~ 170 MeV– Chiral mixing signal did not been measured•

At RHIC and LHC energy ( sNN ~ 200 GeV - 5 TeV), larger signals has been expected, but the huge
combinatorial background and HF contributions disturbed the measurements– Excess at LMR with insufficient precision has been measured– Hadronic matter effects overestimate in a mass range of 0.6 - 0.8 GeV/c2 (?)•

Improvement of detection technology/method is essential– Improvement of vertex detector to determine leptons from HF DCA at low pT– Improve statistics and/or dimuon measurement to reduce combinatorial background effects

34

2020s35

HI program at LHC (ALICE 2)2022 ~•ALICE has been reborn with new read-out andreconstruction system, and Si sensor vertex detector– Just started data taking since 5th July•

Better DCA resolution will be achieved by the new Si
detector covering a wide rapidity range– Mid-rapidity (|η|<1.2) : DCAxy@1GeV/c 60 μm → 30 μm– Fwd-rapidity (2.5η<3.6) : DCAxy@1GeV/c N/A → 80 μm• Better opening angle resolution•

It will record all HI collisions with a 50 kHz interaction rate
– 100 times larger statistics for MB and 10 times larger statistics
0-10% centrality36

HI program at LHC (ALICE 2)2022 ~
Mid-rapidity•

ALICE has been reborn with new read-out andreconstruction system, and Si sensor vertex detector– Just started data taking since 5th July•

Better DCA resolution will be achieved by the new Si
detector covering a wide rapidity range– Mid-rapidity (|η|<1.2) : DCAxy@1GeV/c 60 μm → 25 μm– Fwd-rapidity (2.5η<3.6) : DCAxy@1GeV/c N/A → 80 μm

Forward rapidity• Better opening angle resolution•

It will record all HI collisions with a 50 kHz interaction rate
– 100 times larger statistics for MB and 10 times larger statistics
0-10% centrality37

HI program at LHC (ALICE 2)2022 ~
Mid-rapidity•

ALICE has been reborn with new read-out andreconstruction system, and Si sensor vertex detector– Just started data taking since 5th July•

Better DCA resolution will be achieved by the new Si
detector covering a wide rapidity range– Mid-rapidity (|η|<1.2) : DCAxy@1GeV/c 60 μm → 25 μm– Fwd-rapidity (2.5η<3.6) : DCAxy@1GeV/c N/A → 80 μm

Forward rapidity• Better opening angle resolution•

It will record all HI collisions with a 50 kHz interaction rate
– 100 times larger statistics for MB and 10 times larger statistics
0-10% centrality

38Expected performance of ALICE 2
dN/dMeedy (GeV-1)

Dielectron spectrum
PbPb @ sNN = 5.5 TeV-1

0 - 10%, 2.5E9 events10-2|ye| < 0.84
peT > 0.2 GeV/c
0.0 < p < 3.0
t,ee

10

Sum
Rapp in-medium SF
Rapp QGP
cocktail w/o ρ (± 10%)cc → ee (± 20%)
2.5E9 'measured'
Syst. err. bkg. (± 0.25%)

10-3
10-4
10-5
10-6
0
ALI-PUB-90644

0.5

1

1.5

2

2.5
Mee (GeV/c2)• In dielectron measurement, the rejection power of HF contributes will be improved– 20% more rejection power with keeping signal efficiency• In dimuon measurement, the mass resolution will be improved significantly– Improve mass resolution σω : ~ 50 MeV/c2 → 20 MeV/c2– Down to pT ~ 1 GeV/c thanks to new read-out system• Mass modification at LMR will be measured, but thermal radiation and chiral mixing will be still tough due
to HF

39

Expected performance of ALICE 2
Addendum to the ALICE Upgrade LoI

65

Dimuon spectrum

Dielectron spectrum
10-1

0 - 10%, 2.5E9 events-2|ye| < 0.84
peT > 0.2 GeV/c
0.0 < p < 3.0
t,ee

10

10-3
10-4

×10
300

µµ

MUON only : 1.0 < p

TExpected Stat. for L< 10.0 GeV/c

-1

int
Sum
Cocktail
withoutρRapp in-medium SF
cc → µ µ
Rapp QGP
Rapp QGP
cocktail w/o ρ (± 10%)Rapp in-medium SF
cc → ee (± 20%)
2.5E9 'measured'
Syst. err. bkg. (± 0.25%)

3

dN/dM [dimuons per 10 MeV/c2]

PbPb @ sNN = 5.5 TeV

dN/dM [dimuons per 10 MeV/c2]

dN/dMeedy (GeV-1)

3= 10 nb

200

100

×10

µµ

MUON + MFT : 1.0 < pT < 10.0 GeV/c
Expected Stat. for L

int= 10 nb-1

Cocktail without ρ
cc → µ µ80

Rapp QGP
Rapp in-medium SF

60

40

20

10-5
10-6
0

0

0
0

0.5

1

0.4
2
2.5
Mee (GeV/c2)

1.5

ALI-PUB-90644

0.2

0.6

0.8

1

1.2

1.4

0

0.2

0.4

0.6

0.8

Mass [GeV/c2]

1

1.2

1.4

Mass [GeV/c2]

Figure 2.36: Expected low mass dimuon spectrum in 0-10 % central Pb–Pb collisions at

p

sNN =
5.5 TeV after subtraction of the combinatorial background, normalised to an integrated luminosityof 10 nb 1 without (left panel) and with (right panel) the addition of the MFT to the ALICE Muon
Spectrometer.
20% more rejection power with keeping
signal efficiency• In dielectron measurement, the rejection power of HF contributes will be improved–• In dimuon measurement, the mass resolution will be improved significantly– Improve mass resolution σω : ~ 50 MeV/c2 → 20 MeV/c2
MUON onlysystem: 1.0 < p < 10.0 GeV/c– Down to pT ~ 1 GeV/c thanks to new read-outTµµ[dimuons per 10 MeV/c2][dimuons per 10 MeV/c2]µµ

MUON + MFT : 1.0 < pT < 10.0 GeV/c• Mass modification at LMR will be measured,butthermalradiationandchiralmixing
will
be
still
tough
due
10
to HF

Rapp sum (Syst. Err. c + cocktail)Rapp sum (Syst. Err. Bkg.)

5

Rapp QGP

Rapp in-medium SF

104

5

10

Rapp sum (Syst. Err. c + cocktail)Rapp sum (Syst. Err. Bkg.)
Rapp QGP

Rapp in-medium SF

104

40

Expected performance of ALICE 2
Addendum to the ALICE Upgrade LoI

65

Dimuon spectrum

Dielectron spectrum
10-1

0 - 10%, 2.5E9 events-2|ye| < 0.84
peT > 0.2 GeV/c
0.0 < p < 3.0
t,ee

10

10-3
10-4

×10
300

µµ

MUON only : 1.0 < p

TExpected Stat. for L< 10.0 GeV/c

-1

int
Sum
Cocktail
withoutρRapp in-medium SF
cc → µ µ
Rapp QGP
Rapp QGP
cocktail w/o ρ (± 10%)Rapp in-medium SF
cc → ee (± 20%)
2.5E9 'measured'
Syst. err. bkg. (± 0.25%)

3

dN/dM [dimuons per 10 MeV/c2]

PbPb @ sNN = 5.5 TeV

dN/dM [dimuons per 10 MeV/c2]

dN/dMeedy (GeV-1)

3= 10 nb

200

100

×10

µµ

MUON + MFT : 1.0 < pT < 10.0 GeV/c
Expected Stat. for L

int= 10 nb-1

Cocktail without ρ
cc → µ µ80

Rapp QGP
Rapp in-medium SF

60

40

20

10-5
10-6
0

0

0
0

0.5

1

0.4
2
2.5
Mee (GeV/c2)

1.5

ALI-PUB-90644

0.2

0.6

0.8

1

1.2

1.4

0

0.2

0.4

0.6

0.8

Mass [GeV/c2]

1

1.2

1.4

Mass [GeV/c2]

Figure 2.36: Expected low mass dimuon spectrum in 0-10 % central Pb–Pb collisions at

p

sNN =
5.5 TeV after subtraction of the combinatorial background, normalised to an integrated luminosityof 10 nb 1 without (left panel) and with (right panel) the addition of the MFT to the ALICE Muon
Spectrometer.
20% more rejection power with keeping
signal efficiency• In dielectron measurement, the rejection power of HF contributes will be improved–• In dimuon measurement, the mass resolution will be improved significantly– Improve mass resolution σω : ~ 50 MeV/c2 → 20 MeV/c2
MUON onlysystem: 1.0 < p < 10.0 GeV/c– Down to pT ~ 1 GeV/c thanks to new read-outTµµ[dimuons per 10 MeV/c2][dimuons per 10 MeV/c2]µµ

MUON + MFT : 1.0 < pT < 10.0 GeV/c• Mass modification at LMR will be measured,butthermalradiationandchiralmixing
will
be
still
tough
due
10
to HF

Rapp sum (Syst. Err. c + cocktail)Rapp sum (Syst. Err. Bkg.)

5

Rapp QGP

Rapp in-medium SF

104

5

10

Rapp sum (Syst. Err. c + cocktail)Rapp sum (Syst. Err. Bkg.)
Rapp QGP

Rapp in-medium SF

104

41

Fixed target program at SPS (NA60+)
2027 ~•

NA60+ is the new planning experiment dedicated to muon measurement at SPS– NA60 concept with new Si and fast readout technology– Fixed target experiment with several collision energies sNN = 6 - 17 GeV– Movable detector (change absorber length) to cover large dimuon mass range•

Muon reconstruction performance and statistics will be improved– x10 - 100 statistics

42

Fixed target program at SPS (NA60+)
2027 ~•

NA60+ is the new planning experiment dedicated to muon measurement at SPS– NA60 concept with new Si and fast readout technology

NA60+– Fixed target experiment with several collision energies sNN = 6 - 17 GeV– Movable detector (change absorber length) to cover large dimuon mass range•

Muon reconstruction performance and statistics will be improved– x10 - 100 statistics

43

Fixed target program at SPS (NA60+)
2027 ~•

NA60+ is the new planning experiment dedicated to muon measurement at SPS– NA60 concept with new Si and fast readout technology

NA60+– Fixed target experiment with several collision energies sNN = 6 - 17 GeV– Movable detector (change absorber length) to cover large dimuon mass range•

Muon reconstruction performance and statistics will be improved– x 10 - 100 statistics of NA60

Low energy setup√sNN = 6 - 9 GeV
Absorber = 1.3 m

High energy setup√sNN = 17 GeV
Absorber = 4.6 m

44

Fixed target program at SPS (NA60+)
2027 ~•

NA60+ is the new planning experiment dedicated to muon measurement at SPS– NA60 concept with new Si and fast readout technology

NA60+– Fixed target experiment with several collision energies sNN = 6 - 17 GeV– Movable detector (change absorber length) to cover large dimuon mass range•

Muon reconstruction performance and statistics will be improved– x 10 - 100 statistics of NA60

Low energy setup√sNN = 6 - 9 GeV
Absorber = 1.3 m

High energy setup√sNN = 17 GeV
Absorber = 4.6 m

45

Expected performance of NA60+•

Higher precision measurement at IMR and HMR will be done at several collision energies( sNN=6-17GeV)– Evidence of the chiral mixing ρ-a1 (20 - 30% yield enhancement @ 1 < M < 1.5 GeV/c2)– Early stage temperature measurement via thermal radiation above 2 GeV/c2 within few MeV– Charmonia (J/ψ, ψ(2S), χc) measurement

Chiral mixing

46Expected performance of NA60+•

Higher precision measurement at IMR and HMR will be done at several collision energies( sNN=6-17GeV)– Evidence of the chiral mixing ρ-a1 (20 - 30% yield enhancement @ 1 < M < 1.5 GeV/c2)– Early stage temperature measurement via thermal radiation above 2 GeV/c2 within few MeV– Charmonia (J/ψ, ψ(2S), χc) measurement

Chiral mixing

Thermal radiation

47

Expected performance of NA60+•

Higher precision measurement at IMR and HMR will be done at several collision energies( sNN=6-17GeV)– Evidence of the chiral mixing ρ-a1 (20 - 30% yield enhancement @ 1 < M < 1.5 GeV/c2)– Early stage temperature measurement via thermal radiation above 2 GeV/c2 within few MeV– Charmonia (J/ψ, ψ(2S)) measurement

Chiral mixing

Thermal radiation

Charmonia measurement

48

Fixed target program at LHC (AFTER)
2027 ~•

Fixed target mode with TeV beams•

Several methods of placing target– LHCb has started the program with a gas-jet target•

Energy range on a fixed target– 7 TeV proton beam•s = 2mNEp = 115 GeV• yc.m.s. = 0 → ylab = 4.8 (γ ~ 60)– 2.76 TeV Pb beam•sNN = 2mNEPb = 72 GeV• yc.m.s. = 0 → ylab = 4.3 (γ ~ 40)49

Fixed target program at LHC (AFTER)
2027 ~•

Fixed target mode with TeV beams•

Several methods of placing target– LHCb has started the program with a gas-jet target•

Energy range on a fixed target– 7 TeV proton beam•s = 2mNEp = 115 GeV• yc.m.s. = 0 → ylab = 4.8 (γ ~ 60)– 2.76 TeV Pb beam•sNN = 2mNEPb = 72 GeV• yc.m.s. = 0 → ylab = 4.3 (γ ~ 40)

50

Fixed target program at LHC (AFTER)
2027 ~•

Fixed target mode with TeV beams•

Several methods of placing target– LHCb has started the program with a gas-jet target•

Energy range on a fixed target– 7 TeV proton beam
•

7 TeV

s = 2mNEp = 115 GeV• yc.m.s. = 0 → ylab = 4.8 (γ ~ 60)– 2.76 TeV Pb beam•

2.76 TeV

Boosting: γ~60sNN = 2mNEPb = 72 GeV• yc.m.s. = 0 → ylab = 4.3 (γ ~ 40)

Boosting: γ~40

51

Interesting points of fixed target experimentwith TeV beam•

What is the difference between NA60+?

– QGP is created at the energy sNN = 72 GeV•

Forward detector, but mid-rapidity physics•

Low-pT HF contributions can be identified
thanks to boosting52

Interesting points of fixed target experimentwith TeV beam•

What is the difference between NA60+?

– QGP is created at the energy sNN = 72 GeV•

Forward detector, but mid-rapidity physics•

Low-pT HF contributions can be identified
thanks to boosting53

Interesting points of fixed target experimentwith TeV beam•

What is the difference between NA60+?

– QGP is created at the energy sNN = 72 GeV•

Forward detector, but mid-rapidity physics•

Low-pT HF contributions can be identified

Fwd detectors

thanks to boosting54

Interesting points of fixed target experimentwith TeV beam•

What is the difference between NA60+?

– QGP is created at the energy sNN = 72 GeV•

Forward detector, but mid-rapidity physics•

Low-pT HF contributions can be identified

Fwd detectors

thanks to boosting

Event display of LHCb

• LMR and IMR dimuon performance evaluation has not been started– Very interesting results can be expected55

Interesting points of fixed target experimentwith TeV beam•

What is the difference between NA60+?

– QGP is created at the energy sNN = 72 GeV•

Forward detector, but mid-rapidity physics•

Low-pT HF contributions can be identified

Fwd detectors

thanks to boosting

Event display of LHCb

• LMR and IMR dimuon performance evaluation has not been started– Very interesting results can be expected562030s57

Next generation HI experiment at LHC (ALICE 3)2035 ~•ALICE 3 is the next generation experiment at LHC toinvestigate the property of strongly interacting matter– Based on Si sensor detectors covering |η| < 4– Planning to start from 2035•

ALICE 3 will be designed to meet the required
improvements in lepton measurement– Precise vertexing with low material budget• HF lepton rejection– Good particle identification• Remove combinatorial background– Large collision rate and high-speed readout• Get large statistics

58

Next generation HI experiment at LHC (ALICE 3)2035 ~•ALICE 3 is the next generation experiment at LHC toinvestigate the property of strongly interacting matter– Based on Si sensor detectors covering |η| < 4– Planning to start from 2035•

ALICE 3 will be designed to meet the required
improvements in lepton measurement– Precise vertexing with low material budget• HF lepton rejection– Good particle identification• Remove combinatorial background– Large collision rate and high-speed readout• Get large statistics

59

Next generation HI experiment at LHC (ALICE 3)2035 ~•ALICE 3 is the next generation experiment at LHC toinvestigate the property of strongly interacting matter– Based on Si sensor detectors covering |η| < 4– Planning to start from 2035•

ALICE 3 will be designed to meet the required
improvements in lepton measurement– Precise vertexing with low material budget• HF lepton rejection– Good particle identification• Remove combinatorial background– Large collision rate and high-speed readout• Get large statistics

60

Next generation HI experiment at LHC (ALICE 3)2035 ~•ALICE 3 is the next generation experiment at LHC toinvestigate the property of strongly interacting matter– Based on Si sensor detectors covering |η| < 4– Planning to start from 2035•

ALICE 3 will be designed to meet the required
improvements in lepton measurement– Precise vertexing with low material budget• HF lepton rejection– Good particle identification• Remove combinatorial background– Large collision rate and high-speed readout• Get large statistics

61

Next generation HI experiment at LHC (ALICE 3)2035 ~•ALICE 3 is the next generation experiment at LHC toinvestigate the property of strongly interacting matter– Based on Si sensor detectors covering |η| < 4– Planning to start from 2035•

ALICE 3 will be designed to meet the required
improvements in lepton measurement– Precise vertexing with low material budget• HF lepton rejection– Good particle identification• Remove combinatorial background– Large collision rate and high-speed readout• Get large statistics

62

Detector geometry•

The detector will cover a wide pT and rapidity range– Compact detector design: R < 3m
– Vertexing and tracking with full Si tracker at the barrel and the forward– Particle identification with TOF x 2, RICH, EMCal, and muon chamber– Ultra soft photon measurement with conversion tracker at the forward rapidity

63Detector geometry•

The detector will cover a wide pT and rapidity range– Compact detector design: R < 3m
– Vertexing and tracking with full Si tracker at the barrel and the forward– Particle identification with TOF x 2, RICH, EMCal, and muon chamber– Ultra soft photon measurement with conversion tracker at the forward rapidity

64Detector geometry•

The detector will cover a wide pT and rapidity range– Compact detector design: R < 3m
– Vertexing and tracking with full Si tracker at the barrel and the forward– Particle identification with TOF x 2, RICH, EMCal, and muon chamber– Ultra soft photon measurement with conversion tracker at the forward rapidity

65Detector geometry•

The detector will cover a wide pT and rapidity range– Compact detector design: R < 3m
– Vertexing and tracking with full Si tracker at the barrel and the forward– Particle identification with TOF x 2, RICH, EMCal, and muon chamber– Ultra soft photon measurement with conversion tracker at the forward rapidity

66

Detector geometry•

The detector will cover a wide pT and rapidity range– Compact detector design: R < 3m
– Vertexing and tracking with full Si tracker at the barrel and the forward– Particle identification with TOF x 2, RICH, EMCal, and muon chamber– Ultra soft photon measurement with conversion tracker at the forward rapidity67Precise vertex and track reconstruction•

The innermost 3 layers and 3 disks will be installed inside the beam pipe
– Retractable detector design: Rmin = 5 mm (beam injection) → 1.5 mm (physics run)– Pixel pitch: 5 μm (ALICE 2: ~30μm)– DCAxy & z resolution: ~ 4μm @ 1GeV/c (ALICE 2: 25μm)

68Precise vertex and track reconstruction•

The innermost 3 layers and 3 disks will be installed inside the beam pipe
– Retractable detector design: Rmin = 5 mm (beam injection) → 1.5 mm (physics run)– Pixel pitch: 5 μm (ALICE 2: ~30μm)– DCAxy & z resolution: ~ 4μm @ 1GeV/c (ALICE 2: 25μm)

69Precise vertex and track reconstruction•

The innermost 3 layers and 3 disks will be installed inside the beam pipe
– Retractable detector design: Rmin = 5 mm (beam injection) → 1.5 mm (physics run)– Pixel pitch: 5 μm (ALICE 2: ~30μm)– DCAxy & z resolution: ~ 4μm @ 1GeV/c (ALICE 2: 25μm)

70Particle identification• Electron will be identified with outer and inner TOF and RICH
– Up to 1.5 GeV/c with RICH and down to 0.06 GeV/c with inner TOF• Muon will be identified with RICH and Muon identifier– Up to ~1.5 GeV/c with RICH and over > 1.5 GeV/c with Muon identifier

Inner TOF (20 cm)

Outer TOF (85 cm)

RICH Cherenkov angle

71Particle identification• Electron will be identified with outer and inner TOF and RICH
– Up to 1.5 GeV/c with RICH and down to 0.06 GeV/c with inner TOF• Muon will be identified with RICH and Muon identifier– Up to ~1.5 GeV/c with RICH and over > 1.5 GeV/c with Muon identifier

Inner TOF (20 cm)

Outer TOF (85 cm)

RICH Cherenkov angle

72Collision system•

Data acquisition is based on the ALICE O2 system– Continues readout (trigger less)•

Collide lighter nucleus is proposed– QGP creation in Xe-Xe at LHC energies (confirmed at Run 2)– Achieve higher luminosity, e.g. LXeXe ~ 4 - 5 x LPbPb

73

Collision system•

Data acquisition is based on the ALICE O2 system– Continues readout (trigger less)•

Collide lighter nucleus is proposed– QGP creation in Xe-Xe at LHC energies (confirmed at Run 2)– Achieve higher luminosity, e.g. LXeXe ~ 4 - 5 x LPbPb

74

Collision system•

Data acquisition is based on the ALICE O2 system– Continues readout (trigger less)•

Collide lighter nucleus is proposed– QGP creation in Xe-Xe at LHC energies (confirmed at Run 2)– Achieve higher luminosity, e.g. LXeXe ~ 4 - 5 x LPbPb

75

Expected performance of ALICE 3•

Performance evaluation of dielectron is inprogress

Pair DCA– Rejection of 94% ccbar with keeping 73% ofprompt pairs (17% with ALICE 2)– Able to measure with > 10% uncertainty in themass region where 20% enhancement is expected
due to chiral mixing (ideal detector performance)•

No dimuon performance expectation yet– Rejection of huge combinatorics– Expect better DCA resolution than dielectron– No evaluation of dimuon measurement76

Expected performance of ALICE 3•

Performance evaluation of dielectron is inprogress

Pair DCA– Rejection of 94% ccbar with keeping 73% ofprompt pairs (17% with ALICE 2)– Able to measure with > 10% uncertainty in themass region where 20% enhancement is expected
due to chiral mixing (ideal detector performance)•

Chiral mixing prediction

Expected excess

No dimuon performance expectation yet– Rejection of huge combinatorics– Expect better DCA resolution than dielectron– No evaluation of dimuon measurement

77Expected performance of ALICE 3•

Performance evaluation of dielectron is inprogress

Pair DCA– Rejection of 94% ccbar with keeping 73% ofprompt pairs (17% with ALICE 2)– Able to measure with > 10% uncertainty in themass region where 20% enhancement is expected
due to chiral mixing (ideal detector performance)•

Chiral mixing prediction

Expected excess

No dimuon performance expectation yet– Rejection of huge combinatorics– Expect better DCA resolution than dielectron– No evaluation of dimuon measurement

78Summary•

LMRとIMRのレプトン対測定がSPS、RHIC、LHCで長年行われてきた– 多くの実験がLMRの質量分布の変化を捉えた– 低エネルギー実験では、IMRの分布を用いて衝突初期の温度を測定した– 高エネルギー実験では、HFからのバックグランドが大きく温度測定は実現していない– 初期温度測定、LMRの質量変化の原因解明、カイラルミキシングの信号を検出には、より多くの統計、コンビナトリアルバックグランドの削除、HFレプトンの削除が課題である•

2つのコンビナトリアルバックグランド問題を解決する方法– 統計量をあげる– ミューオン測定に注力する•

2つのHFレプトンの同定力を上げる方法– 高性能なVertex検出器を開発（しかし、これは限界に近づいている）– 衝突点前方で測定することでブーストさせる（LHCb方式）•

多くの次世代実験において、LMRとIMRのレプトン対測定のパフォーマンスを見積もった研究が乏しい– 電子を使った測定は限界がちかい。
– ミューオン測定はまだまだ成熟していない。改善の余地あり。LMR、IMRレプトン対測定において、衝突点前方ミューオンには無限の可能性が広がっている。

79Summary•

LMRとIMRのレプトン対測定がSPS、RHIC、LHCで長年行われてきた– 多くの実験がLMRの質量分布の変化を捉えた– 低エネルギー実験では、IMRの分布を用いて衝突初期の温度を測定した– 高エネルギー実験では、HFからのバックグランドが大きく温度測定は実現していない– 初期温度測定、LMRの質量変化の原因解明、カイラルミキシングの信号を検出には、より多くの統計、コンビナトリアルバックグランドの削除、HFレプトンの削除が課題である•

2つのコンビナトリアルバックグランド問題を解決する方法– 統計量をあげる– ミューオン測定に注力する•

2つのHFレプトンの同定力を上げる方法– 高性能なVertex検出器を開発（しかし、これは限界に近づいている）– 衝突点前方で測定することでブーストさせる（LHCb方式）•

多くの次世代実験において、LMRとIMRのレプトン対測定のパフォーマンスを見積もった研究が乏しい– 電子を使った測定は限界がちかい。
– ミューオン測定はまだまだ成熟していない。改善の余地あり。LMR、IMRレプトン対測定において、衝突点前方ミューオンには無限の可能性が広がっている。

80Summary•

LMRとIMRのレプトン対測定がSPS、RHIC、LHCで長年行われてきた– 多くの実験がLMRの質量分布の変化を捉えた– 低エネルギー実験では、IMRの分布を用いて衝突初期の温度を測定した– 高エネルギー実験では、HFからのバックグランドが大きく温度測定は実現していない– 初期温度測定、LMRの質量変化の原因解明、カイラルミキシングの信号を検出には、より多くの統計、コンビナトリアルバックグランドの削除、HFレプトンの削除が課題である•

2つのコンビナトリアルバックグランド問題を解決する方法– 統計量をあげる– ミューオン測定に注力する•

2つのHFレプトンの同定力を上げる方法– 高性能なVertex検出器を開発（しかし、これは限界に近づいている）– 衝突点前方で測定することでブーストさせる（LHCb方式）•

多くの次世代実験において、LMRとIMRのレプトン対測定のパフォーマンスを見積もった研究が乏しい– 電子を使った測定は限界がちかい。
– ミューオン測定はまだまだ成熟していない。改善の余地あり。LMR、IMRレプトン対測定において、衝突点前方ミューオンには無限の可能性が広がっている。

81Summary•

LMRとIMRのレプトン対測定がSPS、RHIC、LHCで長年行われてきた– 多くの実験がLMRの質量分布の変化を捉えた– 低エネルギー実験では、IMRの分布を用いて衝突初期の温度を測定した– 高エネルギー実験では、HFからのバックグランドが大きく温度測定は実現していない– 初期温度測定、LMRの質量変化の原因解明、カイラルミキシングの信号を検出には、より多くの統計、コンビナトリアルバックグランドの削除、HFレプトンの削除が課題である•

2つのコンビナトリアルバックグランド問題を解決する方法– 統計量をあげる– ミューオン測定に注力する•

2つのHFレプトンの同定力を上げる方法– 高性能なVertex検出器を開発（しかし、これは限界に近づいている）– 衝突点前方で測定することでブーストさせる（LHCb方式）•

多くの次世代実験において、LMRとIMRのレプトン対測定のパフォーマンスを見積もった研究が乏しい– 電子を使った測定は限界がちかい。
– ミューオン測定はまだまだ成熟していない。改善の余地あり。LMR、IMRレプトン対測定において、衝突点前方ミューオンには無限の可能性が広がっている。

82

Muon identifier
Dipole magnet
RICH
VacuumVertex detector

RICH

EMC

Tracker・・・83