Strangeness nuclear physics at J-PARC

Transcription

1 KEK-HN Strangeness nuclear physics at J-PARC Tohoku University H. Tamura

2 Contents 1. Introduction 2. S = -1 systems --- Charge symmetry breaking in LN interaction 3. S = -2 systems --- X-nuclear bound states 4. K bar -nucleus system 5. Future prospects 6. Summary

3 1. Introduction

4 Role of Strangeness in Hadron/Nuclear Physics Quarks/gluons Hadron structure Constituent quarks, other quasi particles How are hadrons formed from quarks and gluons? Hadrons s, c, b quarks play important roles New DOF in nuclear matter SU(3) f sym. in hadron level (constituent quark level) s quarks play unique roles Short-range force by quark picture Baryon-baryon interactions Meson exchange picture Test lattice QCD calculations How are nuclei formed from hadrons? Nuclei

5 Baryon fraction BB interactions and high density matter Attractive LN interaction (U L = -30 MeV) => at least L should appear at 2-2.5r 0 Strange hadronic matter? S - N repul. (U S = +30 MeV) L n p X We need YN, YY int. both in free space and in nuclear matter X - N attr. (U X = -15 MeV) LN: Same in pure neutron matter? LN-SN mixing? SN: How repulsive? XN: Attractive or repulsive? LL: How weakly attractive? Unbound H dibaryon exists? K bar N: How strongly attractive in nuclear matter? YNN, YYN repulsive? Can solve the hyperon puzzle? S - N repul. (U S = +30 MeV) X - N attr. (U X = -15 MeV) C. Ishizuka et al., J.Phys. G35 (2008) ρ

6 (Partly) took data running Under preparation n-rich L hypernuclei 6 L H not observed, 9 L He g spectroscopy of L hypernuclei 4 L He g-ray for CSB 4 L H g-ray, 7 LLi B(M1), YN scattering S ± p scattering exp Weak decay of L hypernuclei L hypernuclear spectroscopy via (e,e K + ) 7 L He, 10 LBe, 12 LB high res. spectra 40 L Ca, 48 LCa Decay pion spectroscopy of L hypernuclei 4 L H mass from 4 LH -> 4 He + p - Lifetime of light L hypernuclei via HI beams Short 3 LH lifetime Present status of strangeness experiments S=-1 systems: more accuracy E13 E40 E10 E63 Jlab E22 MAMI GSI-HypHI, STAR, ALICE E18 S=-2 systems: more events Emulsion experiments X - 14 N bound state More LL hypenuclei X hypernuclear spectroscopy 12 X Be observed E05 X atom X rays H dibaryon search K bar -nuclear systems E03 K - pp search K-pp spec. via 3 He(K -,n) K-pp like bump via d(p +,K + ) Not obderved at E07 KEK E373 E07 E42 E15 L(1405) study via d(k -,n) K-d, K-He atom X rays E57 E62 LEPS, GSI E27 E31

7 2. Single Strangeness Charge Symmetry Breaking in L hypernuclei

8 Charge Symmetry Breaking (CSB) in A=4 hypernuclei CSB in NN force (pp nn) => B( 3 H) - B( 3 He) EM effect ~70 kev CSB in LN force (Lp Ln) B L ( 4 LH) - B L ( 4 LHe) = -350 kev YN interactions models B L ( 4 LH) - B L ( 4 LHe) = 0-70 kev 3 H + L 0 3 He + L Bedjidian et al. PLB 62 (1976) 467 PLB 83 (1979) 252 Old NaI data (K -,p - ) Measure with Ge 1.09±0.02? 1.15±0.04 Measure using weak decay pion Old emulsion data no systematic error L 4 p L H n M. Juric et al. NPB 52 (1973) 1 4 L He Experimental confirmation awaited

9 Decay-pion spectrum at MAMI Emulsion data in binding energy scale 4 L H -> 4 He + p - decays of quasi-free produced hyperon A. Esser et al., PRL 114 (2015) accidental background

10 Old NaI data Hypernuclear g-ray data (2014) 1,.09 3/ M1 PTEP (2015) 081D01

11 J-PARC E13 H. Tamura et al. g spectroscopy setup A Z ( K, - p - ) Tag production of hypernuclei A L Z * p A L Z g - Pion spectrometer SksMinus (2.5 T) Detect g-rays from hypernuclei Ge array Hyperball-J Various PID counters K - K1.8 Beamline Spectrormeter

12 J-PARC E13 H. Tamura et al. g spectroscopy setup A Z ( K, - p - ) Tag production of hypernuclei A L Z * p A L Z g - Pion spectrometer SksMinus (2.5 T) Detect g-rays from hypernuclei Ge array Hyperball-J Various PID counters K - K1.8 Beamline Spectrormeter

13 Hyperball-J Ge cooled down to ~70K (c.f. 92K w/ln2) to reduce radiation damage T. Koike et al., Nucl. Instr. Meth. A 770 (2015) 1 Pulse-tube refrigerator + fast PWO counters Eff. = MeV with 28 Ge(re=60%)

14 4 L He g-ray spectrum Missing mass of 4 He(K -,p - ) p K = 1.5 GeV/c 4 L He 95±13 counts Fit with simulated Doppler-corrected peak shape A peak observed at 1406±2±2 kev

15 Results DB L (1 + ) : 0.03±0.05 MeV A. Esser et al., PRL 114 (2015) T.O. Yamamoto et al., PRL 115 (2015) DB L (0 + ) : 0.35±0.05 MeV (0.26±0.09 MeV) Existence of a large CSB effect confirmed only by g-ray data B L [ 4 LH(0 + ) ] confirmed, suggesting the emulsion 4 LHe(0 + ) data also reliable Large spin dependence in CSB found by combining all the data 4 L H g-ray will be precisely measured in E63

16 What is the origin of the large CSB effect? u/d quark mass difference + EM effects => CSB in hadrons and h-h int. *Exact calc. including S S - mass difference as well as CSB in BB force (Nijmegen SC97e) gives only DB L (0 + ) ~70 kev. SC: tensor dominated LS coupling *p-shell hypernuclear levels are very well reproduced by L-S coupling from D2 interaction. Millener (2005) D2: central only LS coupling Nogga et al., PRL 88 (2002) D2: Akaishi et al., PRL 84 (2000) 3539 *Shell model calc. using D2 gives DB L (0 + ) ~200 kev. A. Gal, PLB 744 (2015) 352 *Ab initio calc. using Bonn-Juelich EFT force (LO) reproduces D(B L (0 + )- DB L (1 + )) ~0.3 MeV. = central dominated LS coupling D. Gazda and A. Gal, PRL 116 (2016) The observed CSB effect is sensitive to the LN-SN coupling force. N N p L L LS coupling S 0 CSB

17 2. Double strangeness ( X-nuclear systems)

18 KEK E373 K. Nakazawa et al. Kiso event found by overall scanning method K. Nakazawa et al.ptep 2015, 033D02 e - a 8 Li p 8 Be a p d = : - - The first evidence for a deeply bound X state -> X - -nucleus is attractive

19 J-PARC E07 K. Nakazawa et al. More S=-2 events with emulsion 10 times more samples of LL hypernuclei and X-nuclear bound states Confirm LL interaction strength, LL XN interaction X-nuclear potential -> X-N interaction Measure X - -atomic X-rays with Ge detectors Shift and width of X-rays -> X-nuclear potential at the nuclear surface X production Measure tracks by counters X absorption Fragmentation Running in 2015 and 2016 Weak decays p p - L Np, LN NN

20 Counts/2 kev X-atomic X-rays via Hyperball-X (Ge array) Select X absorption events with emulsion -> almost no background in X-ray spectrum Emulsion plate Hyperball-X Expected shifts: kev 316 kev 370 kev 511 kev (from π 0 ) simulation e photo = 350 kev sys. error < 0.1 kev (rms) stat. error ~ 0.1 kev (rms) Energy (kev)

21 Spectroscopic Study of Ξ-Hypernucleus, 12 ΞBe, via the 12 C(K -,K + ) Reaction J-PARC E05 Nagae et al. Discovery of Ξ-hypernuclei as a peak(s) Measurement of Ξ-nucleus potential depth and width Coupling between Ξ-nucleus and ΛΛ-nucleus Q1, 37t, 8.7 T/m D1, 86t, 1.5 T S-2S Spectrometer E=1.5 MeV(FWHM) Q2, 12t, 5 T/m Magnets are ready

22 Results of the pilot run (2015) K - p K + Ξ Ξ - /day at J-PARC!! Slide by Nagae/Kanatsuki Using the existing SKS spectrometer (110 msr) p(k -,K + )X - 12 C(K -, K + ) (CH2) QFΞ ΔE~5.4 MeV fwhm

23 Slide by Kanatsuki => Suggesting a rather deep X-nuclear potential

24 4. K bar nuclear systems (K-pp search at J-PARC) => Dote s talk

25 J-PARC E27 T. Nagae et al. K - pp search via d (p +,K + ) L*p reaction 1.69 GeV/c Y. Ichikawa et al., PTEP (2014) 101D03 ΣN-ΛN GeV K-pp? Mass shift ~30 MeV

26 S 0 p mode Proton coincidence spectrum Y. Ichikawa et al., PTEP (2015) 021D01 BE(K-pp) = G = The bump in the ratio spectrum is well explained The ratio of Two energetic protons in Seg2 or 5 One proton coincidence Inclusive

27 J-PARC E15 M. Iwasaki et al. K bar NN search via 3He(K-,n) 27

28 M[K+p+p] The latest result: 3 He(K -,Lp)n Slide by Yamaga E15 2nd performed in with x30 more data E15 1st performed in 2013 Y. Sada, et al, Prog. Theor. Exp. Phys. (2016) 051D01 28

29 4. Future Plans

30 muon for m-e conversion S=-1 systems < 1.1 GeV/c S=-2 systems < 2.0 GeV/c 30 GeV p <31 GeV/c unseparated beam J-PARC Hadron Hall Extension Plan 2 nd production target Abundant S=-1 systems Hyperon Factory < 1.1 GeV/c Precise S=-1 systems Hypernuclear Microscope Dp/p ~ < 2.0 GeV/c Charm/ S=-3 systems <10 GeV/c Separated beam 3rd production target 5 deg extraction ~5.2 GeV/c K 0

31 muon for m-e conversion S=-1 systems < 1.1 GeV/c S=-2 systems < 2.0 GeV/c 30 GeV p <31 GeV/c unseparated beam J-PARC Hadron Hall Extension Plan 2 nd production target Abundant S=-1 systems Hyperon Factory < 1.1 GeV/c Precise S=-1 systems Hypernuclear Microscope Dp/p ~ < 2.0 GeV/c Charm/ S=-3 systems <10 GeV/c Separated beam 3rd production target 5 deg extraction ~5.2 GeV/c K 0

32 Density dependence of LN interaction in matter We have almost no information on BB forces in high density (r > r 0 ) matter Ab-initio calc. of nuclear binding energies => NNN repulsion necessary Similar YNN (YYN, YYY) repulsive forces? Experimentally approach: Precise B L data for wide A of L hypernuclei 0.1 MeV accuracy is necessary Yamamoto, Furumoto, Rijken et al. PRC88 (2013) 2, PRC90 (2014) B/4B repulsion in NNN only g L f L d L MPa s L p L + 3B/4B repulsion in NNN +YNN etc. (Mpa) -B L [MeV] ECS08 only ESC08 only (no 3B force)

33 High-Intensity High-Resolution line (HIHR) Exp. Target Achromatic Focus Mass Slit High Res. Spectrometer Prod. T Electrostatic Separator Intensity: ~ 1.8x10 8 pion/pulse (1.2 GeV/c, 50 m, 1.4msr*%, 100kW, 6s spill, Pt 60mm) Dp/p ~ 1/10000 (Dm~200 kev) Designed by Noumi BE accuracy < 0.1 MeV => Density dependence of LN interaction

34 Recent Highlights in Strangeness NP experiments at J-PARC More accuracy in S=-1 Large CSB effect in A=4 found. 4 LHe g-ray measurement Summary More events in S=-2 X-nucleus bound systems observed. X- 14 N bound system observed in emulsion (Kiso event). A pilot run spectrum for 12 C(K-,K+) 12 XBe shows bound state events. K-pp systems New positive data appeared. A broad peak in (p-,k) reaction may be interpreted as a deep K-pp state. High statistic data in (K-,n) imply a shallower bound state. New experiments at J-PARC + Hadron Hall extension plan => YN interaction in nuclear matter => hyperon puzzle