A search for h’N bound state in the LEPS2-solenoid experiment

（LEPS2ソレノイド実験におけるh’N束縛状態の探索）

A. O. Tokiyasu (ELPH)

ELPH Workshop C024

2019/10/16

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Contents

1.Physics motivation of h’N bound state

2. Search Result of LEPS experiment

3. Search in LEPS2-solenoid experiment

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Introduction

h’

h’

-80 MeV by lsM-150 MeV by NJL

958 MeV: heavy!UA(1) anomaly + CSB

Vacuum nuclei ☆Experimental search:#GSI : C(p,d)X

Ref) Phys. Rev. Lett. 117(2016)202501

#BGOegg : C(g,p) X (h-tag)Coming soon!

☆Linear s model

Inside the nucleus: s meson exchange btw h’ and qqbar condensateh’-N interaction:Similarly the s meson exchange can cause an attractive force h’ N bound state (B.E. several MeV)

Ref) S. Sakai and D. Jido, Phys. Rev. C 88, 064906 (2013))

M-B state : analogy to L(1405) M-BB state : analogy to K-pp

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Hints from the Experiments

☆ p- + p elastic scattering data(-0.64 < cosθ* < 0.86)

☆Beam asymmetry ofg + p h’+ p @GRAAL

W= 1898.8 MeV = 5 MeV3σ dev

W= 1876 MeV = 4 MeV5σ dev

Exotic mechanism may contribute in h’ production near threshold.

Ref) Nuovo Cunebti A75m 163(1983) Ref) Eur. Phys. J. A (2015)51:77

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Search in photo-production☆Property of photo-production

Merit: -free from ISI-polarization observable-complementally to pNDemerit:-Low cross section

☆Reaction1. g + p X

s-channel, PWA2. g + d X + p/n

comparison with QF h’ productionisospin partner search

High Eg

Fwd Proton

gg

h’ N

Np

M

B

M

B

N

MC

MC

g + p h’ + p

cosq of proton

Eg [GeV]5 /16

Mo

m o

f h

’ [G

eV

/c]

Mo

m o

f h

’ [G

eV/c

]

200MeV/c

Theoretical predictionRef) T. Sekihara, S. Sakai, D. Jido

Phys. Rev. C94, 025203 (2016)

- h ’N amplitude: linear s model- h’N bound state signal in hN channel- Comparable with QF h’ production- Distractive interference btw h and h’- Similar behavior to (K-, N) reaction

h'NhN

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MMd(g,p) GeV

h’

h’n signal(17.5101.3 events)

A fit with the signal @ M(h’n)=1.887 GeV/c2

TOF

Dipole Magnet0.7 Tesla

LD2 Target

Start Counter DC2DC3

DC1SVTX

AC(n=1.03)

A few GeVPhotons

Search result in LEPS Ref)N. Muramatsu,HAWAII 2014

-Search for h’n boud state in the reaction d(g,p)X at LEPS. inclusive measurement

-Eg = 1.5 – 2.4 GeV-Data sample : 1/10 of LD2 2006-2007

- Kinematical condition: q<5 deg, Eg= 2.1 GeV

- U.L (95%) of h’n boud state: 8.7 % of QF h’

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For future search- To reduce the BG, exclusive search is necessary.

- Decay mode: (p0N, hN, N, rN, KL, KS, K*L, K*S…)

BGOegg

Ref) Oset. et al., Phys.Lett. B704 (2011) 334

Elastic and inelastic h ’ cross sectionat low energy.

free from p0 P.S.

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Exclusive search

Co

un

ts/1

0 M

eV

By tagging decay particle, BG level will be reduced by factor 5.L tag is efficient to reduce p0 P.S.

LEPS2 experiment

LEPS+NTPC data Date: 2008BPOT : ~1.6x1012

Tgt : LD2

NTPC9 /16

LEPS2 experiment @ SPring-8

Energy : 1.3 < Eγ <2.4/2.9 GeV Beam Intensity >2 × 106 cps Polarization :Linear, CircularTgt : LH2, LD2, C, CH2…1

Backward Compton Scattering method

☆ Acceptance5 ‒ 120 deg (Charged particles)40 ‒ 110 deg (g-rays)

LEPS2 spectrometer (B~1T)

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LEPS2-solenoid detector (1/3)

Ref) R. Kobayakawa, JPS MT

☆Momentum measurement (Dp/p ~ 1% )-TPC (Time Projection Chamber) 50 – 120 deg- DC (Drift Chamber) 5 – 50 deg

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LEPS2-solenoid detector (2/3)

Ref) K. Watanabe, JPS MT

Time resolution ~ 80ps

☆Time-Of-Flight measurement - RPC (Resistive Plate Chamber)- Fwd, Side (Wide, Narrow)

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LEPS2 detector (3/3)

Ref) C. Yoshida, JPS MT

☆K/p identification- AC (Aerogel Cherenkov Counter) 30 – 50 deg

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AC

LEPS2 status- R & D of main detectors are almost done.

- Taking the detector commissioning data with C/CH2 target

- Mass Production of counters and installation is planed by the end of this FY.

- Physics data taking will start from next FY?

☆Physics program:-Penta quark Q+ search-L(1405) property-K-pp bound state property…- h’N bound state search g(d,p)X, (L-tag)

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Yield estimation

InvM2(LP) [GeV2]

InvM

2(L

K)

[G

eV2]

MC

Dalitz plot of (gd->KLp) Eg=2.1 GeV

h’N bound state signal

Y(h’N bound state)= photon number * target number* cross section* BR(YP)* Acceptance* Analysis eff

1.0*1013

5x106 x 200 day

8*1023

Tgt : 160mmr=0.169 g/cm3

10 nb10% ofQ.F. h’

0.1 30% 80%

~1000 ev/year

P.S. production

p:fwdL:side

MC

Mom (p) GeV/c

Mo

m (

L)

GeV

/ccosq (K0)

cosq

(L)

MC

TPC Acceptance

Kinematics (qp < 5deg)

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cosq

(L)

Summary

1.Physics motivation of h’N bound state• Prediction from Linear s model

• Hints from experiments.

2. Search Result of LEPS experiment• Inclusive result @ LEPS

• Exclusive search with NTPC+LEPS data

• Discussion on decay mode

3. Search in LEPS2-solenoid experiment• Introduction of LEPS2-solenoid experiment

• h’N bound state search in g(d,p)X, (L-tag)

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