Nuclei with strangeness at J-PARC

Kiyoshi Tanida (Japan Atomic Energy Agency)07/Oct./2015

NUFRA2015@Kemer, Turkey

Strangeness Nuclear Physics• Nuclei: many body systems of nucleons

– Can be extended by adding other flavors: strangeness, charm, ...

S=0 “surface”

Unexplored “space”

Physics interests• New interaction

– Extended nuclear force to flavor SU(3) world– Unified understanding of Baryon-Baryon force –

What is its origin?– Is traditional meson exchange model enough?

Need quark/gluon picture?

• Property of hyperons in nuclei?– Hyperons can mix easily (e.g., LN-SN, LL-XN)

→ Dynamical systems can be made– Effective mass, magnetic moment, ...?

• What happens to nuclei? Impurity effect?– Collective motion? High density matter?

Relation with neutron star• Naively, hyperons are expected to appear in NS

– E.g., Fermi gas model w/o interactionFermi energy of n: MeV at

– , L S-, X- may be important

• Of course, details depend on nuclear interaction– Most of present calculations

expect hyperons at – Can be studied by SNP at J-PARC– Especially, X potential in nuclei

is a key

• Mass, size, ...?

Nuclear & Hadron Physics in J-PARC

Proton Beam

　 Kaonic nucleusKaonic atom

Ｘ ray

Ｋ−

Implantation ofKaon and the nuclear shrinkage

K-meson

High Density Nuclear Matter,Nucelar Force

Nuclear & Hadron Physics at J-PARC

K1.8

KL

K1.1BR

High-p

SKS

K1.8BRK1.1

K0 → p0 nnL

COMETBeam line

T-Violation

Free quarks Bound quarks

Why are bound quarks heavier ？

Quark

Mass without Mass Puzzle

Origin of Mass

d

uu

d

s

Pentaquark +

He6

Confinement

e-

m-e conversion

,L X N

ZL, S Hypernuclei

LL, X Hypernuclei

Str

an

ge

ne

ss

0

Hypernuclei

-1

-2

High Density Nuclear Matter, Nucelar Force

Experiments at a glance (not all)

Part I.(selected) Results from

recent experiments

E27, E15, & E13

Deeply bound Kaonic nuclei

Akaishi & Yamazaki, PRC 65 (2002) 044005

BK > 100 MeV??

DISTO (PRL 94, 212303)

FINUDAPRL104, 132502

L(1405) = K-p bound state deeply bound nuclei?Kaon condensation in neutron stars?

No observation in HADES, LEPS, …

E27• Search for K-pp by d(p,K+) reaction

– missing mass spectroscopy

Decay counter to detect ppp from Kpp Lp ppp

Y* peak; data = 2400.6 ± 0.5(stat.) ± 0.6(syst.) MeV/c2

sim = 2433.0 (syst.) MeV/c2

``shift” = － 32.4 ± 0.5(stat.) (syst.) MeV/c2

+2.8-1.6

+2.9-1.7

d(π+, K+) at 1.69 GeV/c (Inclusive spectrum)

10

Gaussian fit

Mass shift of L*(1405) and/or S*(1385)?due to final state interaction?

PTEP 101D03 (2014)

Range counter array(RCA) for the coincidence measurement

• RCA is installed to measure the proton from the K-pp.– K-pp→Λp→pπ-p; K-pp→Σ0p→pπ-γp; K-pp→Ypπ→pπp+(etc.)

• Proton is also produced from the QF processes.– π+``n’’→K+Λπ0, Λ→pπ-

• However, these proton’s kinematics is different.

11

p p

K+

π+

We suppress the QF background by tagging a proton. ☆ Seg2 and 5 are free from QF background.More strongly suppress by tagging two protons.

``K-pp’’-like structure(coincidence) • Broad enhancement ~2.28 GeV/c2 has been observed in

the Σ0p spectrum.• Mass: (BE: )• Width:

• dσ/dΩ``K‐pp’’→Σ0p =

• [Theoretical value: ~1.2]

12

T. Sekihara, D. Jido and Y. Kanada-En’yo, PRC 79, 062201(R) (2009).

<1 proton coincidence probability>π+d→K+X, X→Σ0p <2proton coincidence analysis>

PTEP 021D01 (2015)

Discussion on the ``K-pp’’-like structure • Obtained mass (BE ~ 100 MeV) and broad width are

not inconsistent with the FINUDA and DISTO values. – Theoretical calculation for the K-pp is difficult to

reproduce such a deep binding energy about 100 MeV.– Other possibilities?

• A dibaryon as πΛN – πΣN bound states? (It should not decay to the Λp mode because of I = 3/2.) • Λ*N bound state? • A lower πΣN pole of the K-pp? (The K-pp might have the double pole structure like Λ(1405).)• Partial restoration of chiral symmetry on the KN interaction?

13

H. Garcilazo and A. Gal, NPA 897, 167 (2013).

T. Uchino et al., NPA 868, 53 (2011).

A. Dote, T. Inoue and T. Myo, PTEP 2015 4, 043D02 (2015).

S. Maeda, Y. Akaishi and T. Yamazaki, Proc. Jpn. B 89, 418 (2013).

―

E15

E15 result

• No peak below Kpp threshold

E27 result

• Not a kaonic bound state, but NSp resonance??

PTEP 2015, 061D01

E13 g-ray spectroscopy of hypernuclei• 4

LHe: Charge symmetry breaking in LN interaction?compare the mirror nuclei: 4LHe and 4

LH

• 19LF: First g-ray measurement

on sd-shell hypernuclei– How effective interaction

changes compared to p-shell hypernuclei?

• Hyperball-J– 28 germanium detectors

+ PWO Compton suppressordedicated for hypernuclei

E13 result (1) – 4LH

• Eg=1406±2±2 keV

• Corresponding energy in 4LH: 1090±20 keV

Indication of large charge symmetry breaking

• LN-SN coupling effectwith S mass difference?

arXiv:1508.00376

3He1/2+

1+

0+

4LHe

E13 result (2) – 19LF

𝐅𝚲𝟏𝟗

𝐅𝚲𝟏𝟗

𝐅𝚲𝟏𝟗

𝐅❑𝟏𝟗

annhilation

selectedunbound

𝐁❑𝟏𝟎

Doppler shift not corrected

PreliminarySelected

g.s.Unbound

Analysis in progress

Part II.Coming experiments

E03 & E07

E03 experiment• World first measurement of X rays from X-atom

– Gives direct information on the XA optical potential

• Produce X- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays.

• Aiming at establishing the experimental method

K- K+

X-

X ray

Fe targetX- (dss)

Fe

X ray

l (orbital angular momentum)

Ene

rgy

(arb

itrar

y sc

ale)

...

...

...

...

l=n-1 (circular state)l=n-2l=n-3

nuclear absorption

X atom level scheme

Z

X

Z

X

X ray energy shift – real partWidth, yield – imaginary part

Successfully used for p-, K-,`p, and S-

K-

K+

X-

Detectors are ready for installationHyperball-J CH

TOF

DC3

DC2DC1FAC

BH2

BAC

FBHPVAC

KURAMA

E07 LL Hypernuclei

Goal: • 10000 stopped X- on emulsion• 100 or more double-L HN events• 10 nuclides

Chart of double-L hypernuclei

Hybrid emulsion method

Xp LL stay in thenucleus （ ~10 ％）

Production of LL-nuclei by fragmentation

Systematics of LL binding energy• LL binding energy may be different for each nucleus

– For example by hyperon mixing effect

p n L

6LLHe

p n L

5LLHe

p n X

Suppressed Enhanced

p n X

E03/07 run plan in 2015-2017• Test beam for 3 days in October 2015

– Confirm detector performance– Measurement of beam profile

• Installation of KURAMA spectrometer from January– Commissioning beam time in Spring.

• E07 beam time in 2016 with full statistics• E03 beam time is expected after E07.

– Likely in early 2017.– We will have more than 1x1011 K- on target

(10% of proposal)– Observation of X-atomic X ray should be possible,

though finite shift/width may not be observable.

Extended Hadron Hall

Details under discussion

Even further...

Summary• Search for deeply bound Kaonic nuclei (E27, E15)

– Mass shift of L*(1405) and/or S*(1385)?– Hint of deeply bound “Kpp”-like structure observed in d(p+,K+)

reaction, but not observed in (K-,n) reaction– Kaonic nuclei?, SpN?, OR, something else?

• E13: g-ray spectroscopy of hypernuclei– g-ray from 4

LHe observed large charge symmetry breaking

– Several g rays are seen from 19LF (analysis in progress)

• Coming experiments – on doubly strange systems– E03: X-ray spectroscopy of X atom– E07: Systematic study of double-L hypernuclei in emulsion – Expect to run in 2016 & 2017

BACK UPS

Calibration: p(π+, K+)Σ+ at 1.69 GeV/c

32

Σ+

Σ(1385)+

Zoom

M = 1381.1 ± 3.6 MeV/c2

Γ = 42 ± 13 MeVPDG: M = 1382.8 ± 0.35 MeV/c2, Γ = 36.1 ± 0.7 MeV

Data:

θπK dependence( ＋ data, ―sim)

33

< Peak position >＋ data＋ simulation

Y* peak positions are shifted to the low mass side for all scattering angles.

HADES experiment for Λ(1405)

34

M = 1385 MeV/c2,Γ = 50 MeVS-wave Breit Wigner function

The peak position of Λ(1405)is shifted to low-mass side.

E19 ExperimentSearch for pentaquark, Q+

• There are two kinds of usual hadrons (= feel strong force)– Baryon (Fermion): Meson (Boson):

– Color neutrality required from QCDBut they are not the only cases Exotic hadrons

– Pentaquark = 5 quarks

Pentaquark Q+

• First reported in 2003 by LEPS collaboration

• Both positive and negative results– Still controversial

• Mysteries– Why so narrow?

G < 1 MeV– Spin-parity?– What’s that

eventually?

T. Nakano et al.,PRC79 (2009) 025210

High resolution search by p(p-,K-)Q

• A good resolution:~2 MeV (FWHM)– thanks to SKS

• Why high resolution?– Good S/N ratio– Width measurement

Almost certainly G < 1 MeV

• Typical resolution in the past ~ 10 MeV– No high resolution search– There is a good chance

Moritsu et al., PRC90 (2014) 035205

• Spectra well represented by known backgrounds

at both energies

Upper limit on decay width• Based on an effective

Lagrangian approach:Hyodo et al., PTP128 (2012) 523

• Upper limit:

0.36 MeV for ½+

1.9 MeV for ½-

For most conservative cases, taking theoretical uncertainties into account

• Comparable to DIANA result

E10

41

),(),( KK Double Charge-Exchange (DCX)

N~Z (I=0 or 1/2)

N>>Z (I=3/2 or 2)

ordinary nuclei

J-PARC E10

Non Charge-Exchange (NCX)

hyperfragmentsby emulsions exp.

L-hypernuclei

),(),( KK

Neutron rich hypernuclei via (p-,K+) reaction

ΛN-ΣN Mixing in Λ Hypernuclei

if core isospin=0

L SA(I=0) A(I=0)

if core isospin0

L SA(I0) A(I0)

OK!

• Smaller mass difference~300 MeV in DN vs ~80 MeV

• Suppressed in I=0 core– Stronger mixing expected

for neutron rich hypernuclei

Result

• No peak observed

• ds/dW< 1.2 nb/sr– 10 times

smaller than10

LLi– Does it really

bind?

PLB 729 (2014) 39