search for η′ mesic nuclei in gsi/fair -...

1

Search for η′ mesic nuclei in GSI/FAIR

Y. Ayyad, J. Benlliure, K.-T. Brinkmann, S. Friedrich, H. Fujioka**, H. Geissel, J. Gellanki, C. Guo, E. Gutz, E. Haettner, M. N. Harakeh, R. S. Hayano, Y. Higashi, S. Hirenzaki, C. Hornung, Y. Igarashi, N. Ikeno, K. Itahashi*, M. Iwasaki, D. Jido, N. Kalantar-Nayestanaki, R. Kanungo, R. Knoebel, N. Kurz, V. Metag, I. Mukha, T. Nagae, H. Nagahiro, M. Nanova, T. Nishi,H. J. Ong, S. Pietri, A. Prochazka, C. Rappold, M. P. Reiter, J. L. R. Sánchez, C. Scheidenberger, H. Simon, B. Sitar, P. Strmen, B. Sun, K. Suzuki, I. Szarka, M. Takechi, Y. K. Tanaka, I. Tanihata, S. Terashima, Y. N. Watanabe, H. Weick, E. Widmann, J. Winfield, X. Xu, H. Yamakami, J. Zhao

*spokesperson, ** co-spokesperson !

!for Super-FRS collaboration

!Osaka University, Universidade de Santiago de Compostela, Universitaet Giessen, Kyoto University, GSI, University of Groningen, Beihang University, The University of Tokyo, Nara Women's University, KEK, RIKEN, Tokyo Metropolitan University, Saint Mary’s University, Technische Universitaet Darmstadt, Comenius University Bratislava, Stefan Meyer Institut, Niigata University

Nagahiro, Jido, Fujioka, KI, Hirenzaki, PRC87(13)045201. KI, Fujioka et al., PTP 128 (12) 601.

Kenta Itahashi Advanced Meson Science Laboratory, RIKEN

for η-PRiME collaboration

RIKEN Nishina Center, Kenta Itahashi 2

M=548 MeV/c2

M=498 MeV/c2

M=140 MeV/c2

0

250

500

750

1000

[MeV/c2]

η′

η′ and other PS mesons

ηK

π

M=958 MeV/c2


M=140 MeV/c2

0

250

500

750

1000

[MeV/c2]η′ and other PS mesons

π

M=958 MeV/c2

mη′ < √3mπ (Weinberg, 1975)

√3mπ

η problem

η′


Kobayashi, Maskawa, PTP44(70)1422 ‘t Hooft, PRD14(76)3432.

T. Kunihiro, Phys. Lett. B219(89)363. Klimt, Lutz, Vogl, Weise, NPA516(90)429.

Large η′ mass can be explained

�q̄q�

q

q̄

q̄

q

timeKobayashi-Maskawa-’t Hooft-type interaction

UA(1) quantum anomaly × χ-symmetry breaking

6-point vertex

5

η′ Meson

Hirenzaki

6

0

250

500

750

1000

[MeV/c2]

η′

η

K

π

In-medium PS mesonsPartial restoration of dynamical breaking of χ symmetry

Nagahiro et al., PRC 87 (2013) 045201 Jido et al., NPA 914 (2013) 354

Nagahiro et al, PRC 74, 045203 (2006)

ρ/ρ0

NJL model

7

0

250

500

750

1000

[MeV/c2]

η′

η′ mesic nuclei search

11CQ. Mass shift of

~ 150 MeV/c2 can be observed in experiment?

Naive estimation shows 30% reduction

of |mη′−mη|

30 %

Jido, Nagahiro, Hirenzaki, PRC85(2012)032201(R)

η

η′

8

η′ Mesic Nuclei in (p,d) Reaction

η′ × 11C mesic nuclei

12C η′ 11C

η′ transfer reaction + missing mass measurement

Tp = 2.50 GeV → q ~ 400 MeV/c

KI, Fujioka et al., PTP 128 (12) 601.

9

Theoretical Prediction

Nagahiro et al., PRC87(13)045201.

η′-nucleus potential:

12C(p,d) at Tp = 2.50 GeV

ρ: nucleon density V0: Real potential depth

W0: Imaginary potential depth

10

p dη′Signal

Spectrum in Inclusive Measurement at GSI

12C(p,d)11C ⊗ η′

Nagahiro et al., PRC87(13)045201.

11

p dη′

p d

ππ

π

12C(p,d)11C ⊗ η′

Background

Signal

Spectrum in Inclusive Measurement at GSI

)=<(150, 5) MeV0

, W0

(V

Excitation Energy [MeV]-40 -20 0 2

cou

nts/

2MeV

260000

265000

270000

275000

280000

285000

0

multi-π

BK

Simulation

KI, Fujioka et al., PTP 128 (12) 601.

ρ0

ρ(r) Vη’ = (V0+iW0)

V0, W0 : real, imaginary part of optical potential

)=−(150, 5) MeV0, W0(V

)=−(150, 10) MeV0, W0(V

)=−(150, 20) MeV0, W0(V


)=−(100, 5) MeV0, W0(V

)=−(100, 10) MeV0, W0(V

)=−(100, 20) MeV0, W0(V


coun

ts/2M

eV

260

265

270

275

280

285 )=−(200, 5) MeV0, W0(V×103

coun

ts/2M

eV

260

265

270

275

280

285 )=−(200, 10) MeV0, W0(V


coun

ts/2M

eV

255

260

265

270

275

280

285 )=−(200, 20) MeV0, W0(V

　　　　　　

background (e.g.,p+N→d+πʼ’s)

285000

280000

275000

270000

265000

260000

285000

280000

260000

coun

ts/2

MeV

　　　　　　

275000

270000

265000

285000

280000

coun

ts/2

MeV

255000

　　　　　　

260000

275000

270000

265000

　　　　　　　　　　　　　-40 0-20 20 　　　　　　　　　　　　　-40 0-20 20 　　　　　　　　　　　　　-40 0-20 20Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV]

Simulation

ηʼ’ production

coun

ts/2

MeV

Simulated spectra of inclusive measurement assuming 4.5 day DAQ

!S/N ratio ~ O(1/100) at most

K. Itahashi et al., PTP 128,601(2012)

(V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2)

Simulation of inclusive measurement

13


)=<(100, 20) MeV0

, W0

(V

cou

nts/

2MeV

255000

260000

265000

270000

275000

280000

285000

60 80 100 120 140 160 180 200

6

8

10

12

14

16

18

20

0

10

20

30

40

50

60

70

80

90

100

|VԾ| [MeV]

|WԾ|

[MeV

]

Structure-finding Probability

for 95 % C.L.

in 4.5 days DAQ

)=<(150, 5) MeV0

, W0

(V


cou

nts/

2MeV

260000

265000

270000

275000

280000

285000

0

14

-50-100-150

-10

-20

V0 [MeV]

W0 [MeV](=-Γ/2)

NJL linear σ QMC

COSY-11

0

chiralunitary

theory

exp. (η′A int.)exp. (η′N int.)

COSY-11

CBELSA/TAPS

COSY-11

Structure-finding Probability for First Step (GSI)

H. Fujioka

15

6080100120140160180200

6

8

10

12

14

16

18

20

-50-100-150

-10

-20

V0 [MeV]

W0 [MeV](=-Γ/2)

NJL linear σ QMC

COSY-11

0

chiralunitary

theory

exp. (η′A int.)exp. (η′N int.)

COSY-11

CBELSA/TAPS

COSY-11

Structure-finding Probability for First Step (GSI)

H. Fujioka

NUSTAR 2015

16

Measurement Objectives S/N

GSI step 1

(p,d) inclusive

extremely good statistics for overall structure + BK study poor

GSI/FAIR step 2

(p,dp) exclusive*

extended sensitivity for excited + ground states good

FAIR step≧2

(p,dx) exclusive*

exclusive + decay mode studies good

Step-by-step approach

17

p

p

d

d

d

η

p

π

p

N

Background

Principles of Exclusive Measurement at GSI/FAIR

Signals

p d

ππ

π

pη′→pη

Nη′→pπ

η′NN→pN

p dη′Signal

NUSTAR 2015

18


GSI step 1

(p,d) inclusive


GSI/FAIR step 2

(p,dp) exclusive*


FAIR step≧2

(p,dx) exclusive*



19

First step Inclusive measurement GSI SIS-S437 in 2014/Aug

C target12 (4 g/cm )2

MWDC×2

SC

Aerogel Cherenkov (AC)

20

d ~ 4 k/spill at S4 (signal)

Scintillator (SC)

ACS4

S2

p beam (Tp = 2.5 GeV)

p′~ 800 k/spill at S4 (background)

Fragment Separator (FRS)

18m

Achromatic

Dispersive (3.6cm/%)

Production setup at FRS

C target12 (4 g/cm )2

MWDC×2

SC

Aerogel Cherenkov (AC)

21

d ~ 4 k/spill at S4 (signal)

Scintillator (SC)

ACS4

S2

p beam (Tp = 2.5 GeV)

p′~ 800 k/spill at S4 (background)


18m

Achromatic

Dispersive (3.6cm/%)

Production setup at FRS

perfect PID

MWDC Analysis

time[day]2 3 4 5 6 7 8

drift

lengt

h [m

m]

0.5

0.55

0.6

0.65

0.7

0.75

0.8

- MWDC(XX’XX’UU’VV’)×2 were used. !- Tracking : drift time (measured) → drift length → χ2 fitting for 2 MWDCs !- Iterative analysis for calibration : temporary drift length → tracking → evaluate and update drift length !- Time dependence of relation between drift time and drift length !!

Drift length calibration

Aug

. 2

0:0

0

Aug

. 4

for drift time=1555 (TDC channel)

14001420 1440 14601480 1500 15201540 1560 15801600-3

-2

-1

0

1

2

3

Drift Time [channel]

Drift

Leng

th [m

m]

Measured drift time [TDC channel]

Eval

uate

d dr

ift le

ngth

[m

m]

Dri

ft le

ngth

[m

m]

Time dependence of drift time to drift length relation

Aug

. 3

Aug

. 5

Aug

. 6

Aug

. 7

Aug

. 8

~1day

22

-100 -50 0 50 100Eex - E0 [MeV]

0%

FRS scaling -2%

+2%

23

Production run (~ 5 days) - 7 settings of FRS Bρ from -2% to 2% → -90 MeV < Eex-E0 < +40 MeV covered - spectrometer calibration every 6 hours

Region in excitation energy

Spectrometer settings for wide mass region

CD2 target(1 g/cm )2

24

d (Pd = 2.82 GeV/c) ~mono-energetic at 0 degree

S4

S2

p (Tp = 1.6 GeV )

Calibration Run

D(p,d)p elastic scattering for ~mono-energetic d


dispersive (3.6cm/%)

18m

a

X at Focal Plane [mm]-100 -50 0 50 100

Cou

nt

0

1000

2000

3000

4000

5000

6000

as4cor_xFocal plane position (online, ion-optics roughly corrected)

! - energy loss and straggling calculation - spectrometer momentum resolution - beam momentum spread

σX = 2.7 mm (CD2 calibration run)

preliminary

Expected mass resolution : σ ~ 2 MeV/c2 (production run) 25

FRS scaling by -2%

0%

2%

1%

-1%

Calibration Run

26

MM-M(11C)-M(etaprime) [MeV/c2]-150 -100 -50 0 50 100 1500

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Sample spectrum of a very small part of accumulated data

~ 1 % of statistics for a FRS setting.

Acceptance uncorrected

12C(p,d) Td = 2.5 GeV

run864

)=<(150, 5) MeV0

, W0

(V


cou

nts/

2MeV

260000

265000

270000

275000

280000

285000

0

cf. simulation

coun

ts /

2 [M

eV/c

2 ]preliminary

NUSTAR 2015

27


GSI step 1

(p,d) inclusive


GSI/FAIR step 2

(p,dp) exclusive*


FAIR step≧2

(p,dx) exclusive*



28Proton Kinetic Energy [MeV]

0 100 200 300 400 500 600 700 8000

10

20

30

40

50

60

70

80

90

100310×

Y.K. Tanaka and Y. Higashi

η′p→ηpη′p→πp

η′p→ππp η′pN→pN

p

p

d

d

d

η

p

π

p

N

Signals

Tagging high-momentum protons (300-600 MeV)

pη′→pη

Nη′→pπ

η′NN→pN

Principles of Exclusive Measurement at GSI/FAIR

29

MWDCD1 D4

D3D2

Target 12C 20 g

Scintillators

10cm

1cm-thick PS

high-refractive-index (n~1.2) aerogelbrass

5cm-thick PS

10cm

1cm-thick PS

high-refractive-index (n~1.2) aerogel

brass

5cm-thick PS

Beam Tp = 2.5 GeV Ip > 108/spill

10cm

1cm-thick PS


brass

5cm-thick PS

beam dump trigger~400/spill

bk 80k/spill

p d

ππ

π

Background suppression by signal tagging

For next step

Pilot run for exclusive measurement at GSI

p

p

d

d

d

η

p

π

p

N

30

Roadmap for η′

2015 2020 2025

S437 analysis

Construction of proton detector

Better stat./Pilot exclusive measurement

Detector test

Production exclusive measurement

4pi detector development

4pi installation

Systematic study Decay mode study

10cm

1cm-thick PS


brass

5cm-thick PS

FAIR GSI

unofficial roadmap (or wishes)

31

Summary

• Search for η′ meson bound states in 11C by missing mass

spectroscopy at GSI/FAIR • η′ is interesting in relation to UA(1) anomaly × χ-symmetry • Just finished first physics run for inclusive (p,d) • PID perfect • Successfully accumulated targeted statistics with good

resolution ~ 2 MeV/c2 • Preparation for semi-exclusive measurement

search for η′ mesic nuclei in gsi/fair -...

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