HYPERNUCLEAR PHYSICS

HYPERNUCLEAR PHYSICS Hypernuclei are bound states of nucleons with a strange baryon (L hyperon).

Extension of physics on N-N interaction to system with S≠0

Internal nuclear shells 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 aspectL-N force vs N-N force will provide clues to the QCD description of the N-N Force (one-p and one-r exchange suppressed)

Perspectives of Hypernuclear Physics at Jlab in the 12 GeV eraF. Garibaldi on behalf of Jlab hypernuclear collaboration

L N interaction

V

✔ most of information is carried by the spin dependent part

✔ doublet splitting is determined by D, sL, T

(r)

Hypernuclear Spectroscopy

new aspects of hyernuclear structure

production of mirror hypernuclei Charge Symmetry Breaking ?

Hall A Kaon collaborationF.Garibaldi (INFN), S. Frullani (INFN). M.Iodice (INFN), J.LeRose (Jlab), P. Markowitz (FIU),G. Chang (Maryland)

E94-107 - E-98-108 - E 07-01296 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+)L/S 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.

✓ 7Li(e,e’k) 7LHe A clear peak of the 7He ground state for the first time.

CSB term puzzle, (CSB term is essential for A=4 hypernuclei). our understanding of the CSB effect in the N L interaction potential is still imperfect.

✓ 9Be(e,e’K+)9LLi: Disagreement between the standard model of p-

shell hypernculei and the measurements, both for the position of the peaks and for the cross section.

✓ 12C(e,e’K+) 12LB: 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. ✓.16O(e,e’K+)16

LN: The fourth peak ( in p state) position disagrees with theory. This might be an indication of a large spin-orbit term SL. Binding Energy BL=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 1 20 50 200 1057

Elementary ProcessStrangeness electro-production

Fine structure Baryon-baryon interaction in SU(3) LS coupling in large isospin hypernuclei Cluster structure

Hyperonization

Softening of

EOS ?

Superfluidity

E05-1156,7Li 10,11B 12C 51V 52Cr 89Y

Single-particle potentialDistinguishability of a L hyperon

U0(r), mL*(r), VLNN, ...

Medium - Heavy hypernuclei

E-94-107

208Pb

Bare LN Int.Few body calc. Mean Field TheoryCluster calc.

Shell model

Decay Pion Spectroscopy to Study L-Hypernuclei

12C

-

Weak mesonic two body decay( - 0.1)

1- 0.02- ~150 keV

Ground state doublet of 12ΛB

Precise BΛ Jp and

Direct Production

p

e’

e12C K

+

Example:

LHypernuclear States:Λs (or Λp) coupled to low lying core nucleus

12ΛBg.s.

E.M.

γ*

12ΛB

- 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 Hypernuclear Spectroscopy by e.m. probe successfully

established at Jlab confirming its excellence for studying hypernuclei

The experiments required important, challenging modifications to the Hall A and Hall C detector setup

Crucial contributions from Italian and Japanese collaborations

The new equipment performed excellently.

Best characteristics of Hall A and Hall C detectors setup understood

Merging collaborations and getting the best out of the two detectors

in order to best continue into the 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 interactionConstructed from limited hyperon scattering data(Meson exchange model: Nijmegen, Julich)

YN, YY effective interaction in finite nuclei(YN G potential)

Hypernuclear properties, spectroscopic informationfrom structure calculation (shell model, cluster model…)

Energy levels, Energy splitting, cross sectionsPolarizations, weak decay widthshigh quality (high resolution & high statistics)

spectroscopy plays a significant role

G-matrix calculation

H.-J. Schulze, T. Rijken PHYSICAL REVIEW C 84, 035801 (2011)

Understanding the N-N ForceIn terms of mesons and nucleons:

Or in terms of quarks and gluons:

V =

Hypernuclei Provide Essential Clues

For the N-N System:

For the L-N System:

Hypernuclei Provide Essential Clues

For the N-N System:

For the L-N System: Long Range Terms Suppressed (by Isospin)

L single particle energiesE05-115 (HKS-HES)

E94-107(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 1.128 + 0.439A-2/3

The First reliable observation of 7LHe

An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)

A Test of Charge Symmetry Breaking

• Begin with a theoretical description of these nuclei without CSB

The First reliable observation of 7LHe

An example of what we learn from HypernucleiA Highlight of JLab E01-011 (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

LH –4LHe

and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.

The First reliable observation of 7LHe

An example of what we learn from HypernucleiA Highlight of JLab E01-011 (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

LH –4LHe

and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.

Old result on 7LHe

(M.Juric et al. NP B52 (1973) 1)Inadequate for a serious comparison

-BL (MeV)

-6.730.02 0.2 MeV from a L n n

The First reliable observation of 7LHe

An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)

A Test of Charge Symmetry Breaking Compare with new measurements of 7

LHe 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

LH –4LHe

and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.

-BL (MeV)

-6.730.02 0.2 MeV from a L n n

The First reliable observation of 7LHe

An example of what we learn from HypernucleiA Highlight of JLab E01-011 (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

LH –4LHe

and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.

Present Status of L Hypernuclear Spectroscopy

Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.

(2011)

52LV

Tremendous Progress, but More Nuclei and Higher P

recision are Needed

To Fully Understand the L-N/N-N Force Diffe

rences 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/parity3. 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 states6. 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

PR12-10-001 - Study of Light - Hypernuclei by Spectroscopy of Two Body Weak Decay Pions

Fragmentation of Hypernuclei And Mesonic Decay inside Nucleus

Free: L p + p -

2-B: ALZ A(Z + 1) + p -

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 BL 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: