HYPERNUCLEAR PHYSICS Hypernuclei are bound states of nucleons with a strange baryon (  hyperon). Extension of physics on N-N interaction to system with S#0 Internal nuclear shell are not Pauli-blocked for hyperons Spectroscopy many body problems   - N interaction Few-body aspects and YN, YY interaction Mean field aspects of nuclear matter Astrophysical aspect  force vs N-N force will provide clues to the QCD description of the N-N Force (one-  and one-  exchange suppressed) Perspectives of Hypernuclear Physics at Jlab in the 12 GeV era F. Garibaldi on behalf of Jlab hypernuclear collaboration

 interaction V ✔ most of information is carried out by the spin dependent part ✔ doublet splitting determined by , s , T (r) Hypernuclear Spectroscopy

new aspects of hyernuclear structure production of mirror hypernuclei  Charge Symmetry Breaking ?

Hall A Kaon collaboration F.Garibaldi (INFN), S. Frullani (INFN). M.Iodice (INFN), J.LeRose (Jlab), P. Markowitz (FIU),G. Chang (Maryland) E E E collaborators - 30 Institutions,

Hall C hardware contribution

hadron arm septum magnets RICH Detector electron arm aerogel first generation aerogel second generation To be added to do the experiment Hall A deector setup

✓ p(e,e′K+)  The data suggest that not only do the present models fail to describe the data over the full angular range, but that the cross section rises at the forward angles. The failure of existing models to describe the data suggests the reaction mechanisms may be incomplete. ✓ 7 Li(e,e’k) 7  He A clear peak of the 7 He ground state for the first time. CSB term puzzle, (CSB term is essential for A=4 hypernuclei).  understanding of the CSB effect in the  interaction potential is still imperfect. ✓ 9 Be(e,e’K+) 9  Li: Disagreement between the standard model of p-shell hypernculei and the measurements, both for the position of the peaks and for the cross section. ✓ 12 C(e,e’K+) 12  B: for the first time a measurable strength with sub-MeV energy resolution has been observed in the core-excited part of the spectrum. The s part of the spectrum is well reproduced by the theory, the p shell part isn’t. ✓. 16 O(e,e’K+) 16  N: The fourth peak ( in p state) position disagrees with theory. This might be an indication of a large spin-orbit term S . Binding Energy B  =13.76±0.16 MeV measured for the first time with this level of accuracy

Hypernuclei in a wide mass range Neutron/Hyperon star Strangeness matter Light Hypernuclei (s,p shell) A Elementary Process Strangeness electro-production Fine structure Baryon-baryon interaction in SU(3)  coupling in large isospin hypernuclei Cluster structure Hyperonization Softening of EOS ? Superfluidity E ,7 Li 10,11 B 12 C 51 V 52 Cr 89 Y Single-particle potential Distinguishability of a  hyperon U 0 (r), m  *(r), V  NN,... Medium - Heavy hypernuclei E Pb Bare  N Int. Few body calc. Mean Field Theory Cluster calc. Shell model

Decay Pion Spectroscopy to Study  -Hypernuclei 12 C  - Weak mesonic two body decay (   -  0.1) ~150 keV Ground state doublet of 12  B Precise B  J p and  Direct Production p e’ e 12 C K +K + Example:  Hypernuclear States:  s (or  p ) coupled to low lying core nucleus  12  B g.s. E.M.  ** 12  B - Weak 2 body mesonic decay at rest uniquely connects the decay pion momentum to the well known structure of the decay nucleus, B  and spin-parity of the ground state of hyperfragment

Summary and outlook  HypernuclearSpectroscopy by e.m. probe successfully established at Jlab confirming to be excellent tool to study hypernuclei  Hypernuclear Spectroscopy by e.m. probe successfully established at Jlab confirming to be excellent tool to study hypernuclei important, challenging modifications  The experiments required important, challenging modifications on the Hall A and Hall C detector setup  Crucial contributions from Italian and Japanese collaborations  The new equipments showed excellent performance.  Best characteristics of Hall A and Hall C detectors setup understood Merging collaborations and getting the best out of the two detectors to be able to do next step in 12 GeV era  Jlab beam and detectors make it unique in the international panorama for this physics  HypernuclearSpectroscopy by e.m. probe successfully established at Jlab confirming to be excellent tool to study hypernuclei  Hypernuclear Spectroscopy by e.m. probe successfully established at Jlab confirming to be excellent tool to study hypernuclei important, challenging modifications  The experiments required important, challenging modifications on the Hall A and Hall C detector setup  Crucial contributions from Italian and Japanese collaborations  The new equipments showed excellent performance.  Best characteristics of Hall A and Hall C detectors setup understood Merging collaborations and getting the best out of the two detectors to be able to do next step in 12 GeV era  Jlab beam and detectors make it unique in the international panorama for this physics

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YN, YY Interactions and Hypernuclear Structure Free YN, YY interaction Constructed from limited hyperon scattering data (Meson exchange model: Nijmegen, Julich ) YN, YY effective interaction in finite nuclei (YN G potential) Hypernuclear properties, spectroscopic information from structure calculation (shell model, cluster model… ) Energy levels, Energy splitting, cross sections Polarizations, weak decay widths high quality (high resolution & high statistics) spectroscopy plays a significant role G-matrix calculation

H.-J. Schulze, T. Rijken PHYSICAL REVIEW C 84, (2011)

Light hypernuclei (A<~20) Fine structure Baryon-baryon interaction in SU(3) LS coupling in large isospin hypernuclei Cluster structure Heavy hypernuclei (A>~50) Single-particle potential Distinguishability of a L hyperon U 0 (r), m L *(r), V LNN,... Neutron star (A ~ ) Hyperonization  Softening of EOS ? Superfluidity Hypernuclei in the wide mass range -- toward strange matter -- Short range nature of the LN interaction : no pion exchange meson picture or quark picture ?

Understanding the N-N Force In terms of mesons and nucleons: Or in terms of quarks and gluons: V =

Hypernuclei Provide Essential Clues For the N-N System: For the  -N System:

Hypernuclei Provide Essential Clues For the N-N System: For the  -N System: Long Range Terms Suppressed (by Isospin)

 single particle energies E (HKS-HES) E (Hall A HY) E01-011(HKS) Calculation by John Millener, using a Woods-Saxon potential with a depth of 28 MeV and a radius parameter of A -2/3

JLab’s Hypernuclear Program To Date NucleusWhat Have We Learned? 12 C(e,e’K + ) 12  B A reference nucleus. Demonstrates improved resolution relative to  -production (0.6 vs 2 MeV). Complementary measurement of H(e,eK‘)  and H(e,e’K)  0 permits absolute energy calibration. S-shell portion of spectrum well-reproduced by theory, p-shell portion is not. H(e,e’K)  and H(e,e’K)  0 Measurement of the elementary interactions – H(e,eK‘)  and H(e,e’K)  0 – permits absolute energy calibration and normalization of production cross sections. 16 O(e,e’K + ) 16  N Within errors, binding energy and excited levels of mirror hypernuclei ( 16  O from pion production experiments and 16  N from (e,e’K) are in agreement 9 Be(e,e’K + ) 9  Li Theory doesn’t reproduce observed energies and strengths. Possible explanations include current calculations of the underlying core nucleus 8  Li structure and spectroscopic factors. 28 Si(e,e’K + ) 28  Al First sd shell hypernuclear spectroscopy w/ isotopically pure target. Preliminary determination of mass suggests that it disagrees by ~1 MeV with shell model prediction (potential major impact). 7 Li(e,e’K + ) 7  He First reliable observation of 7  He w/ good statistics – comparison between 7  He, and data on 7  Li* and 7  Be from gamma decay experiments provides data on CSB in hypernuclei. The experimental results are NOT reproduced by theory, bringing potential into question. 52 Cr(e,e’K + ) 52  V New data under analysis. Demonstrated the feasibility of measurements of heavy hypernuclei,, w/ deeply bound , which are not accessible using the gamma ray decay measurement technique. 10 Be(e,e’K + ) 10  Li New data under analysis. Will be compared with related data on as a cross check on modifications to CSB likely to be done to explain the 7  He / 7  Li* / 7  Be result.

The First reliable observation of 7  He An example of what we learn from Hypernuclei A Highlight of JLab E (HKS) A Test of Charge Symmetry Breaking Begin with a theoretical description of these nuclei without CSB

The First reliable observation of 7  He An example of what we learn from Hypernuclei A Highlight of JLab E (HKS) A Test of Charge Symmetry Breaking Begin with a theoretical description of these nuclei without CSB A Naïve calculation of the CSB effect, which explains 4  H – 4  He and available s, p-shell hypernuclear data, predicts opposite shifts for A=7,T=1 iso- triplet  Hypernuclei.

The First reliable observation of 7  He An example of what we learn from Hypernuclei A Highlight of JLab E (HKS) A Test of Charge Symmetry Breaking Begin with a theoretical description of these nuclei without CSB A Naïve calculation of the CSB effect, which explains 4  H – 4  He and available s, p-shell hypernuclear data, predicts opposite shifts for A=7,T=1 iso- triplet  Hypernuclei. Old result on 7  He (M.Juric et al. NP B52 (1973) 1) Inadequate for a serious comparison

-B  (MeV)  0.02  0.2 MeV from  n n The First reliable observation of 7  He An example of what we learn from Hypernuclei A Highlight of JLab E (HKS) A Test of Charge Symmetry Breaking Compare with new measurements of 7  He Measured shift has the opposite sign to the predicted shift! Begin with a theoretical description of these nuclei without CSB A Naïve calculation of the CSB effect, which explains 4  H – 4  He and available s, p-shell hypernuclear data, predicts opposite shifts for A=7,T=1 iso- triplet  Hypernuclei.

-B  (MeV)  0.02  0.2 MeV from  n n The First reliable observation of 7  He An example of what we learn from Hypernuclei A Highlight of JLab E (HKS) A Test of Charge Symmetry Breaking Naïve theory does not explain the experimental result. Begin with a theoretical description of these nuclei without CSB A Naïve calculation of the CSB effect, which explains 4  H – 4  He and available s, p-shell hypernuclear data, predicts opposite shifts for A=7,T=1 iso- triplet  Hypernuclei.

Present Status of  Hypernuclear Spectroscopy Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564. (2011) 52  V Tremendous Progress, but More Nuclei and Higher Precision are Needed To Fully Understand the  N/N-N Force Differences  JLab and JPARC Programs

Complementary Additional Measurements Proposed for the 12 GeV Upgrade The addition of measurements of p decay of hypernuclei will permit 1.Precise (~±20 keV) determination of  binding energies of a variety of ground state light hypernuclei 2.Determination and confirmation of ground state spin/parity 3.Direct measurement of  binding energy differences from multiple mirror pairs of light hypernuclei at ground state to investigate CSB and Coulomb effect 4.Searching for the neutron drip line limit of light hypernuclei – heavy hyper- hydrogen 5.Searching for evidence of the existence of isomeric hypernuclear states 6.Studying impurity nuclear physics – B(E2) measurement and medium effect of baryons – B(M1) measurement through lifetime

✓ Few-body aspects and YN, YY interaction ✓ Mean field aspects of nuclear matter ✓ Many body and astrophysical aspect

PR Study of Light - Hypernuclei by Spectroscopy of Two Body Weak Decay Pions Fragmentation of Hypernuclei And Mesonic Decay inside Nucleus Free:  p +  - Free:  p +  - 2-B: A  Z  A (Z + 1) +  - 2-B: A  Z  A (Z + 1) +  - High yield high precision 2 body decay pion spectroscopy physics may be extracted High yield and unique decay feature allow high precision measurement of 2 body decay pion spectroscopy from which variety of physics may be extracted Decay at rest the pion momentum is uniquely connected to the well known structure of the decay nucleus, allow determination of B  (~20keV) and spin-parity of the g.s. of hyperfragments, study Charge Symmetry Breaking (CSB)

PR Study of Light - Hypernuclei by Spectroscopy of Two Body Weak Decay Pions Fragmentation of Hypernuclei And Mesonic Decay inside Nucleus Free:  p +  - Free:  p +  - 2-B: A  Z  A (Z + 1) +  - 2-B: A  Z  A (Z + 1) +  - High yield high precision 2 body decay pion spectroscopyphysics may be extracted High yield and unique decay feature allow high precision measurement of 2 body decay pion spectroscopy from which variety of physics may be extracted - High yield of hypernuclei (bound or unbound in continuum) makes high yield of hyper fragments, i.e. light hypernuclei which stop primarily in thin target foil - Decay at rest the pion momentum is uniquely connected to the well known structure of the decay nucleus, allow determination of B  and spin-parity of the ground state of hyperfragments, study CSB High momentum transfer in the primary production sends most of the background particles forward, thus pion momentum spectrum is expected to be clean with minor 3-boby decay pions: