H.M. QNP Bejing1 1 Hunting  -mesic nuclei Hartmut Machner (FZ Jülich & University Duisburg-Essen) GEM collaboration Outline Why are  -mesic nuclei interesting? Search via production experiments Search via Final State Interaction (FSI) p+d  + 3 He tensor pol. d+d 

H.M. QNP Bejing2 Model for  and  ’ meson in 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) G. ’t Hooft, Phys.Rev.D14,3432 (76) V  (r) V  ’ (r) V  (r) 2 V  ’ (r) V  (r) g D : constant g D = 0 (w/o KMT term) g D = g D (  =0) e -(  /  0) 2 11 B

H.M. QNP Bejing3 Heuristic 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+A  3 He+[(A-1)  ]: Break up protons have same magnetic rigidity as 3 He’s.  Large cross section. –p+A  3 He+[(A-2)  ]: Magnetic rigidity of beam particles differ by a factor of two from 3 He’s. Small cross section. 

H.M. QNP Bejing4 Order of magnitude HHG d, 3 He L.-C. Liu

H.M. QNP Bejing5 Missing mass spectroscopy emitted particle Incident particle target meson deuteron-hole Momentum transfers for  -mesic nuclei formation

H.M. QNP Bejing6 Previous searches Pfeiffer et al. PRL:  + 3 He  0 +p+X, 3.5  Sokol et al.:  + 12 C  + +n+X; Both ejectiles are anti-correlated; =300 MeV, =100 MeV Lieb et al. (  +,p) Chrien et al. PRL q=200 MeV/c inclusive

H.M. QNP Bejing7 Reactions 3 He in BIG KARL, all beam momentum  -p back to back in ENSTAR 3-fold coincidence + 3 more constraints!

H.M. QNP Bejing8 ENSTAR Detector TOF

H.M. QNP Bejing9 ENSTAR Detector NIM A 596 (08) 31

H.M. QNP Bejing10 Mounting phase

H.M. QNP Bejing11 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 coincidence  Pion leaves the detector: outer layer fires  Proton stopped in the middle layer

H.M. QNP Bejing12 Two spectrometer settings

H.M. QNP Bejing13 Time- and 3 He spectra

H.M. QNP Bejing14 η-nucleus formation cross section estimation L ≈ 5*10 35 cm -2 ≈75 hours of the beam for each setting ≈ 5 * 10 8 particles per second on the target 1 mm Aluminium target efficiency: 0.70±0.07 loss due to geometry and cuts: Bump = 50 pb ε branch = 1/3 N*  N(2T z +1) N 0* -- p2 00 n1 N +* ++ n2 00 p1

H.M. QNP Bejing15 Summed data PRC 70 (2009) (R)

H.M. QNP Bejing16 classical description in „a“ and „r 0 “ alternative description  final state interaction Tacid assumption: s-wave, and then d  /d  =  /4  Sign convention: Goldberger

H.M. QNP Bejing17 Binding conditions Quasi-bound requires: Im(a  A ) > 0 from unitarity |Im(a  A )| < |Re(a  A )| to have a pole in the negative energy half plane Re(a  A ) < 0 to have a bound state, but |FSI| 2  Re(a  A ) 2 |Q 0 (  3 He)|<|Q 0 (  4 He)| Otherwise: virtual (unphysical) state

H.M. QNP Bejing18 Total cross sections

H.M. QNP Bejing19 3 He-  production amplitude T. Mersmann et al., PRL 98 (07) COSY11 + old data <50 MeV/c no need for effective range PLB 649 (07)258

H.M. QNP Bejing20 dd  Eur. Phys. J. A 26 (2005) 421

H.M. QNP Bejing21 GEM dd  In order to extract s-wave production, tensor polarised deuteron beam Target area:

H.M. QNP Bejing22 Raw data (  +1)/2 (  -1)/2 -(  +1)/2 -(  -1)/2

H.M. QNP Bejing23 Unpolarised cross sections Exp.a0a0 a2a2 a4a4 ANKE 1.30 ± ±0.19 GEM 1.27 ± ± ±0.07 s, p and d-waves!

H.M. QNP Bejing24 Excitation Function Same momentum range as in p+d, but less data points. Cross section less than 5%! How to extract s-wave?

H.M. QNP Bejing25 Polarised beam dp elastic scattering

H.M. QNP Bejing26

H.M. QNP Bejing27 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 Bejing28 H. M., Mumbai, Febr Final result NP A 821 (2009) 193 PWA spin ampl.

H.M. QNP Bejing29 Final result scatt. length effective range

H.M. QNP Bejing30 Summary  Search for -mesic nuclei employing recoil free kinematics.  We see an enhancement in the spectra after detecting 3 final particles: 3 He at zero degree and  - +p back to back.  25 Mg  bound state: BE13 MeV, FWHM10 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.

H.M. QNP Bejing31 The GEM Collaboration M. Abdel-Bary a, S. Abdel-Samad a, A. Budzanowski d, A. Chatterjee i, J. Ernst g, P. Hawranek a,c, R. Jahn e, V. Jha i, S. Kailas i, K. Kilian a, Da. Kirilov a,h, Di. Kirilov h, S. Kliczewski d, D. Kolev f, M. Kravcikova m, T. Kutsarova e, M. Lesiak a,c, J. Lieb j, H. Machner a, A. Magiera c, G. Martinska l, H. Nann k, N. Piskinov h, L. Pentchev e, D. Protic a, J. Ritman a, P. von Rossen a, B. J. Roy i, P. Shukla i, R. Siudak d, I. Sitnik h, M. Ulicny a,l, R. Tsenov f, J. Urban l, G. Vankova a,f, C. Wilkin n, G. Wüstner b 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.

H.M. QNP Bejing32 Thank you for your attention

H.M. QNP Bejing33 FSI

H.M. QNP Bejing34 Excitation function:dp → 3 He  2 /n free =0.82