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Hunting Hunting -mesic nuclei-mesic nuclei

Hartmut MachnerHartmut Machner(FZ Jülich & University Duisburg-Essen)(FZ Jülich & University Duisburg-Essen)

GEM collaborationGEM collaboration

Outline

• Why are -mesic nuclei interesting?

• Search via production experiments

• Search via Final State Interaction (FSI)

• p+d+3He

• tensor pol. d+d

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Model for Model for and and ’’ meson in meson in medium (Hirenzaki et al.)medium (Hirenzaki et al.)

Nambu-Jona-Lasinio model with the KMT interaction: explicit breaking of Ua(1) symmetry

Kobayashi, Maskawa Prog.Theor.Phys.44, 1422 (70)Kobayashi, Maskawa Prog.Theor.Phys.44, 1422 (70)G. ’t Hooft, Phys.Rev.D14,3432 (76)G. ’t Hooft, Phys.Rev.D14,3432 (76)

VV(r)(r)

VV’’(r)(r)

VV’’(r)(r)VV(r)(r)

2

VV’’(r)(r)

VV(r)(r)

ggDD : constant : constant ggDD = 0 (w/o KMT term) = 0 (w/o KMT term) ggDD = g = gDD((=0) e=0) e-(-(//0)0) 22

11B

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Heuristic approachHeuristic approach

• A rather large s-wave -nucleon scattering length lead to the idea of bound -nucleus systems.

• This would be a strong bound system, contrary to pionic atoms (Coulomb bound).

• How to observe?• Recoil free transfer reactions like in hyper-nuclei and in pionic atoms

cases.• Nuclear projectiles:

– d+A3He+[(A-1)]:• Break up protons have same magnetic rigidity as 3He’s. • Large cross section.

– p+A3He+[(A-2)]:• Magnetic rigidity of beam particles differ by a factor of two from 3He’s. • Small cross section.

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Order of magnitudeOrder of magnitude

HHG

d,3He

L.-C. Liu

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Missing mass spectroscopyMissing mass spectroscopy

emitted particleemitted particle

Incident particleIncident particle

targettargetmesonmeson

deuteron-holedeuteron-hole

Momentum transfers for Momentum transfers for -mesic nuclei-mesic nuclei formation formation

A A-3

p

3He

p

p-

N *

N *

N *

N *

0

20

40

60

80

100

120

140

160

180

200

q-

mes

ic (

Me V

/ c)

1600 1700 1800 1900p

beam (MeV/c)

B=0 MeV

B=-10 MeV

B=-20 MeV

p+27Al3He+(25Mg)

B=-30 MeV

B=-70 MeV

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Previous searchesPrevious searches

Pfeiffer et al. PRL: +3Hep0+p+X, 3.5

Sokol et al.: +12Cp++n+X; Both ejectiles are anti-correlated;

<Ep>=300 MeV, <En>=100 MeV

Lieb et al. (p+,p)

Chrien et al. PRL• q=200 MeV/c• inclusive

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27 3 25

0*

( can not decay, becau

(1535

se its bound!)

)

p Al He Mg

n N n

p

p

-

ReactionsReactions

3He in BIG KARL, all beam momentum

p-p back to back in ENSTAR

3-fold coincidence + 3 more constraints!

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ENSTAR

3

2 2

dp H

Ae

A

- -

0*

0(1535)

p

nN N

p

n

pp

pp

-

Detector

TOF

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ENSTAR DetectorENSTAR Detector

NIM A 596 (08) 31

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Mounting phaseMounting phase

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Proton + Aluminium target

Particle identification with BK focal plane detectors

(high threshold cuts light particles)

Event of interest:Two correlated particles: 5+2/3=7/8 fold coincidencePion leaves the detector: outer layer firesProton stopped in the middle layer

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Two spectrometer settings

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Time- andTime- and 3 3He spectraHe spectra

100

101

102

103

104

105

cou n

ts /

4 M

eV

-30 -20 -10 0BE (MeV)

23.79 23.80 23.81 23.82MM (GeV)

3He in BK+ENSTAR+bb

3He in BK+ENSTAR

only 3He in BK

0

10

20

30

0

200

400

600

800

cou

nts

0

10000

20000

30000

40000

50000

0 200 400 600 800 1000time (arb. units)

FP ENSTAR

FP (3He) ENSTAR

FP (3He) ENSTARall gates

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η-nucleus formation cross section estimation

L ≈ 5*1035 cm-2 ≈75 hours of the beam for each setting

≈ 5 * 108 particles per second on the target1 mm Aluminium target

efficiency: 0.70±0.07 loss due to geometry and cuts: Bump = 50 pb

εbranch = 1/3

L

N

exp. 152 54(stat.) 21(syst.) pb N* p N (2Tz+1)

N0* p- p 2

N0* p0 n 1

N+* p+ n 2

N+* p0 p 1

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Summed dataSummed data

PRC 70 (2009) 012201(R)

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2 2 2 2iB B

f

p df f FSI f FSI

p d

20

11

12f f

FSIi a p a r p

-

classical description in „a“ and „r0“

alternative description

- final state interaction

Tacid assumption:

s-wave, and then d/d=/4p

Sign convention: Goldberger

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Binding conditionsBinding conditions

Quasi-bound requires:

• Im(aA) > 0 from unitarity

• |Im(aA)| < |Re(aA)| to have a pole in the negative energy half plane

•Re(aA) < 0 to have a bound state, but

|FSI|2 Re(aA)2

|Q0(3He)|<|Q0(4He)|

Otherwise: virtual (unphysical) state

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Total cross sections

100

200

300

400

500

600

700

800

(n

b)

0

100

200

300

400

500

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 = p/m

-2 0 2 4 6 8 10 12 (MeV)

BilgerAdamRausmannMersmannSmyrskiMeyerBanaigsLoireleuxKirchnerGEM *0.73

FSI (Sibirtsev)

pd3He

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3He- production amplitude

T. Mersmann et al., PRL 98 (07) 242301

3

0.1 1.00.5 0.910.7 0.8 1.5 2.6 fm

Hea i

- -

0.20 0.01.9 0.1 2.1 0.2 fmr i

-

COSY11 + old data <50 MeV/c

no need for effective range

PLB 649 (07)258

3 2.9 2.7 3.2 1.8 fmHe

a i 0| | 0.30 MeVQ

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dd

Eur. Phys. J. A 26 (2005) 421

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GEM ddGEM dd

beam direction

point

target

Luminosity Right Scintillators

Luminosity Left Scintillators

M detector

In order to extract s-wave production, tensor polarised deuteron beam

Target area:

M detector

beam directiontarget

point

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Raw dataRaw data

(p+1)/2

(p-1)/2

-(p+1)/2

-(p-1)/2

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Unpolarised cross sectionsUnpolarised cross sections

Exp. a0 a2 a4

ANKE1.30

±0.18

-0.79

±0.19

GEM1.27

±0.03

-0.29

±0.06

1.65

±0.07

s, p and d-waves!

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Excitation FunctionExcitation Function

Same momentum range as in p+d, but less data points. Cross section less than 5%!

How to extract s-wave?

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Polarised beamPolarised beam

dp elastic scattering

(radians)0 1 2 3 4 5 6

un

po

l/N

po

lN

0.97

0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

= +1)zz

] (p+0.019cos21.00[1+0.0011+0.0354cos= -1)

zz] (p-0.016cos21.02[1-0.0007+0.0352cos

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Better fit than partial wave amplitudes (s, p, 2d waves), because less parameters (4 instead of 7)

Angular dependence due to s-d interference

H.M. QNP Bejing 28H. M., Mumbai, Febr. 09 28

FinalFinalresultresult

NP A 821 (2009) 193

PWA

spin ampl.

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Final resultFinal result

scatt. length

effective range

30 0| | 4MeV > | ( He) |Q Q

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Summary Search for -mesic nuclei employing recoil free kinematics. We see an enhancement in the spectra after detecting 3 final

particles: 3He at zero degree and p-+p back to back.

25Mgbound state: BE13 MeV, FWHM10 MeV 5 effect We have measured angular distributions of cross sections and

tensor analysing power for the reaction dd at 16.6 MeV above threshold

s-wave strength could be extracted s-wave strength of other experiments (Willis et al., Wronska et

al.) extracted FSI shows Im a (-) = 0.0(5) fm. This indicates a small

absorption because the nucleons are strongly bound The -nucleus levels in heavy nuclei thus might be fairly

narrow.

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The GEM CollaborationThe GEM CollaborationM. Abdel-Barya, S. Abdel-Samad a, A. Budzanowski d, A. Chatterjee i, J. Ernst g, P. Hawranek a,c, R.

Jahne, V. Jhai, S. Kailasi, K. Kilian a, Da. Kirilova,h, Di. Kirilovh, S. Kliczewski d, D. Kolev f,M. Kravcikova m, T. Kutsarova e, M. Lesiaka,c, J. Lieb j, H. Machner a, A. Magiera c, G. Martinska l,

H. Nann k, N. Piskinovh, L. Pentchev e, D. Protic a, J. Ritman a, P. von Rossen a, B. J. Roy i, P. Shuklai,R. Siudak d, I. Sitnikh, M. Ulicny a,l, R. Tsenov f, J. Urban l, G. Vankovaa,f, C. Wilkinn, G. Wüstnerb

a. Institut für Kernphysik, Forschungszentrum Jülich, Jülich, Germany b. Zentrallabor für Elektronik, Forschungszentrum Jülich, Jülich, Germany

c. Institute of Physics, Jagellonian University, Krakow, Poland d. Institute of Nuclear Physics, Pan, Krakow, Poland

e. Institute of Nuclear Physics and Nuclear Energy, Sofia, Bulgaria f. Physics Faculty, University of Sofia, Sofia, Bulgaria

g. Institut für Strahlen- und Kernphysik der Universität Bonn, Bonn, Germany h. LHE, JINR, Dubna, Russia

i. Nuclear Physics Division, BARC, Bombay, India j. Physics Department, George Mason University, Fairfax, Virginia, USA

k. IUCF, Indiana University, Bloomington, Indiana, USA l. P. J. Safarik University, Kosice, Slovakia

m. Technical University, Kosice, Kosice, Slovakia n. Department of Physics & Astronomy, UCL, London, U.K.

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Thank you for your attention

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FSIFSI

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Excitation function:dp→3He

2/nfree=0.82