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.,  N-  N,  -  N) → Dynamical systems can be made – Effective mass, magnetic moment,...? What happens to nuclei? Impurity effect? – Collective motion? High density matter?

Relation with neutron star

Nuclear & Hadron Physics in J-PARC

Proton Beam Kaonic nucleus Kaonic atom Ｘ ray Ｋ−Ｋ− Implantation of Kaon 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 K1.8BR K1.1 K 0 →  0 L COMET Beam line T-Viola tion Free quarks Bound quarks Why are bound quarks heavier ？ Quark Mass without Mass Puzzle Origin of Mass d u u d s Pentaquark  +  He 6 Confinement e-e-  -e conversion   N Z ,  Hypernuclei ,  Hypernuclei Strange ness 0 Hypernuclei -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) B K > 100 MeV?? DISTO (PRL 94, ) FINUDA PRL104,  (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( ,K + ) reaction – missing mass spectroscopy Decay counter to detect pp  from Kpp   p  pp 

Y* peak; data = ± 0.5(stat.) ± 0.6(syst.) MeV/c 2 sim = (syst.) MeV/c 2 ``shift” = － 32.4 ± 0.5(stat.) (syst.) MeV/c d(π +, K + ) at 1.69 GeV/c (Inclusive spectrum) 10 Gaussian fit Mass shift of  * (1405) and/or  * (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→Σ 0 p→pπ - γp; K - pp→Ypπ→pπp+(etc.) Proton is also produced from the QF processes. – π + ``n’’→K + Λπ 0, Λ→pπ - However, these proton’s kinematics is different. 11 p p K+K+ π+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/c 2 has been observed in the Σ 0 p spectrum. Mass: (BE : ) Width: dσ/dΩ ``K ‐ pp’’→Σ 0 p = [Theoretical value: ~1.2] 12 T. Sekihara, D. Jido and Y. Kanada-En’yo, PRC 79, (R) (2009). π + d→K + X, X→Σ 0 p 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 , 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 N  resonance?? PTEP 2015, 061D01

E13  -ray spectroscopy of hypernuclei 4  He: Charge symmetry breaking in  N interaction? compare the mirror nuclei: 4  He and 4  H 19  F: First  -ray measurement on sd-shell hypernuclei – How effective interaction changes compared to p-shell hypernuclei? Hyperball-J – 28 germanium detectors + PWO Compton suppressor dedicated for hypernuclei

E13 result (1) – 4  H E  =1406±2±2 keV Corresponding energy in 4  H: 1090±20 keV  Indication of large charge symmetry breaking  N-  N coupling effect with  mass difference? arXiv: He 1/  He

E13 result (2) – 19  F selected unbound Doppler shift not corrected Selected Unbound Analysis in progress

Part II. Coming experiments E03 & E07

E03 experiment World first measurement of X rays from  -atom – Gives direct information on the  A optical potential Produce  - by the Fe(K -,K + ) reaction, make it stop in the target, and measure X rays. Aiming at establishing the experimental method K-K- K+K+  X ray Fe target  (dss) Fe X ray

l (orbital angular momentum) Energy (arbitrary scale)... l=n-1 (circular state) l=n-2 l=n-3 nuclear absorption  atom level scheme Z  Z  X ray energy shift – real part Width, yield – imaginary part Successfully used for  , K ,  p, and  

K-K- K+K+ -- Detectors are ready for installation Hyperball-J CH TOF DC3 DC2 DC1 FAC BH2 BAC FBH PVAC KURAMA

E07  Hypernuclei Goal: stopped   on emulsion 100 or more double-  HN events 10 nuclides Chart of double-  hypernuclei Hybrid emulsion method

 p   stay in the nucleus （ ~10 ％） Production of  -nuclei by fragmentation

Systematics of  binding energy  binding energy may be different for each nucleus –For example by hyperon mixing effect p n  6  He pn  5  He pn  Suppressed Enhanced pn 

E03/07 run plan in 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 – We will have more than 1x10 11 K  on target (10% of proposal) – Observation of  -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   (1405) and/or   (1385)? – Hint of deeply bound “Kpp”-like structure observed in d(  ,K + ) reaction, but not observed in (K ,n) reaction – Kaonic nuclei?,  N?, OR, something else? E13:  -ray spectroscopy of hypernuclei –  -ray from 4  He observed  large charge symmetry breaking – Several  rays are seen from 19  F (analysis in progress) Coming experiments – on doubly strange systems – E03: X-ray spectroscopy of  atom – E07: Systematic study of double-  hypernuclei in emulsion – Expect to run in 2016 & 2017

BACK UPS

Calibration: p(π +, K + )Σ + at 1.69 GeV/c 32 Σ+Σ+ Σ(1385) + Zoom M = ± 3.6 MeV/c 2 Γ = 42 ± 13 MeV PDG: M = ± 0.35 MeV/c 2, Γ = 36.1 ± 0.7 MeV Data:

θ πK dependence ( ＋ data, ―sim) 33 ＋ 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/c 2, Γ = 50 MeV S-wave Breit Wigner function The peak position of Λ(1405) is shifted to low-mass side.

E19 Experiment Search for pentaquark,   There are two kinds of usual hadrons (= feel strong force) – Baryon (Fermion): Meson (Boson): – Color neutrality required from QCD But they are not the only cases  Exotic hadrons – Pentaquark = 5 quarks

Pentaquark   First reported in 2003 by LEPS collaboration Both positive and negative results – Still controversial Mysteries – Why so narrow?  < 1 MeV – Spin-parity? – What’s that eventually? T. Nakano et al.,PRC79 (2009)

High resolution search by p(  ,K  )  A good resolution: ~2 MeV (FWHM) – thanks to SKS Why high resolution? – Good S/N ratio – Width measurement Almost certainly  < 1 MeV Typical resolution in the past ~ 10 MeV – No high resolution search – There is a good chance

Moritsu et al., PRC90 (2014) 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 MeV for ½ - For most conservative cases, taking theoretical uncertainties into account Comparable to DIANA result

E10 41 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) hyperfragments by emulsions exp.  -hypernuclei Neutron rich hypernuclei via (  -,K + ) reaction

ΛN-ΣN Mixing in Λ Hypernuclei if core isospin=0  A( I =0) if core isospin  0  A( I  0) OK! Smaller mass difference ~300 MeV in  N vs ~80 MeV Suppressed in I=0 core – Stronger mixing expected for neutron rich hypernuclei

Result No peak observed d  /d  < 1.2 nb/sr – 10 times smaller than 10  Li – Does it really bind? PLB 729 (2014) 39