(958)-nucleus bound states and their formations by missing mass spectroscopies

Transcription

1 YITP workshop on Hadron in Nucleus 31 Oct. 2 Nov. 213, Maskawa Hall, Kyoto University (958)-nucleus bound states and their formations by missing mass spectroscopies Hideko NAGAHIRO (Nara Women s University) H. Nagahiro, D.Jido, H. Fujioka, K.Itahashi, S. Hirenzaki, PRC87(13)4521 [(p,d) theo.] Itahashi, Fujioka, Geissel, Hayano, Hirenzaki, Itoh, Jido, Metag, Nagahiro, Nanova, Nishi, Okochi, Outa, Suzuki, Tanaka, Weick, PTP128(12)61, [(p,d) H. Nagahiro, S. Hirenzaki, E. Oset, A. Ramos, PLB79(12)87, [chiral unitary, (,N)] D. Jido, H. Nagahiro, S. Hirenzaki, PRC85(12)3221(R) [sym vs., (,N)] H.Nagahiro, M.Takizawa, S. Hirenzaki, PRC74(6)4523 [NJL, (,p)] H. Nagahiro, S. Hirenzaki, PRL94(5)23253 [(,p)]

2 Heavy mass of the (958) meson schematic view of the mass of,, & Jido et al., PRC85(12)3221(R) Nagahiro et al., PRC (213) cf.) NJL model with KMT,,, U A (1) anomaly effect,, massless,, Meson mass [MeV] U A (1) breaking (KMT term [1,2] ) [1] Kobayashi-Maskawa PTP44(7)1422 [2] G. t Hooft, PRD14(76)3432 ChS manifest dynamically broken dyn. & explicitly broken Costa et al.,plb56(3)171, Nagahiro-Takizawa-Hirenzaki, PRC74(6)4523 2

3 property in medium Phenomenologically poorly understood small scattering length? Re.8fm, COSY, Moskal et al., PLB474()416]? nucleus.1fm, [, Moskal et al., PLB482()356] [estimated from FSI on observed at COSY] M.Nanova et al., PLB71(12)6 smaller absorption width in medium? Γ ; 1GeV/ MeV@, CBELSA/TAPS [M.Nanova et al., PLB71(12)6] [estimated transparency ratio ] mass reduction in finite T/? Δ 15 [NJL model w/ KMT interaction] Δ 2 MeV? in finite T [in Au+Au collisions at RHIC] [experimentally observed enhanced production of soft pions Interpreted as mass reduction of in the hot medium [Csorgo et al., PRL15(1)18231]] 3

4 Our strategy for studying the properties Possible bound states and their formation» with missing mass spectroscopy : (,p), (,N), (p,d), H.N., S.Hirenzaki, PRL94 (5) H.N., M.Takizawa, S.Hirenzaki, PRC74 (6)4523 and references in title page! in-medium strongly affects its observation possibilities Experimental information [CBELSA/TAPS [M.Nanova et al., PLB71(12)6] Γ 1525MeV@ [estimated transparency ratio ] phenomenological approach [H.N., S. Hirenzaki, E. Oset, A, Ramos, PLB] Based on : Coupled-channel calculation [Oset-Ramos, PLB74(11)334] P-B N, N, N)+ V-B (K Λ, K Σ) + o B 4

5 Phenomenological approach for interaction Oset-Ramos, PLB74(11)334 Unitarized scattering amplitude by coupled-channel BS eq. Interaction kernel (1) Weinberg-Tomozawa interaction : pseudoscalar-baryon (PB) channel,,λ,σ their result :.1fm (2) Vector meson-baryon (VB) channel their result :.3fm by the - mixing ~.1.8 fm [PLB ] (3) coupling of the singlet component of pseudoscalar to baryons Borasoy, PRD61()1411 Kawarabayashi-Ohta, PTP66(81)1789 B B free parameter.1fm 5

6 phenomenological estimation for Optical potential [H.N., S. Hirenzaki, E. Oset, A. Ramos, PLB79(12)87] t N We consider only the attractive case & energy-independent potential. Re and Im with various values fm in unit of MeV Re Im 6

7 phenomenological estimation for The reason why Re Im in coupled channel calculation Kawarabayashi-Ohta, PTP66(81)1789 Borasoy, PRD61()1411 B B gives attraction This interaction WT interaction for resembles that of the anomaly effect discussed by D. Jido PRC85(12) seems to dominate the interaction contributes mostly to the elastic channel & barely to the inelastic channel B M B width [small] ongoing work [A. Hinata (NaraWU) et al. ] energy-dependence of : we discuss over a wide energy range (deep bound state possible value evaluated from, ex.) cross section at threshold ) 7

8 formation by (p,d) GSI ( Y.K.Tanaka s talk) missing mass spectroscopy K. Itahashi, H. Fujioka et al., PTP128(12)61 proton kinetic energy 2.5GeV target : 12 C, ( 16 O, 4 Ca) forward reaction : d = deg. neutron -hole p target meson d Momentum transfer q [GeV/c] momentum transfer elementary cross section No information m 5 MeV m 1 MeV proton kinetic energy Tp [GeV] J.Klaja et al., PRC81(1)3529 (COSY) assumptions 3 / Ω Itahashi et al., PTP128(12)61 K.Nakayama in private comm. 8

9 target-nucleus dependence merit demerit to see peaks light nucleus less (shallow) bound states less hole-states simpler structure heavy nucleus many (deeper) bound states many hole-states complex structure observed spectrum bound states :,, MeV case 11 C 15 O 39 Ca s, p s, p, d s, p, d, f, g one neutron-hole state (excited states of daughter nucleus) hole Δ Γ hole Δ Γ hole Δ Γ p 3/2 p 1/2 d 3/2 s 1/ p 3/ s 1/ s 1/ d 5/ p 1/ p 3/ s 1/

10 target-nucleus dependence : strong attraction case light nucleus less (shallow) bound states less hole-states simpler structure heavy nucleus many (deeper) bound states many hole-states complex structure [nb/sr/mev] C target, 16 O 1,1 MeV 4 Ca / 35 3 / / / 25 / / 2 / 15 1 / E ex E [MeV] E ex E [MeV] E ex E [MeV] 1

11 target-nucleus dependence : shallower case light nucleus less (shallow) bound states less hole-states simpler structure heavy nucleus many (deeper) bound states many hole-states complex structure 4 Shallower case :, 5,5 MeV 12 C target 4 Ca target 3 [nb/sr/mev] / / [nb/sr/mev] E ex E [MeV] E ex E [MeV] 11

12 Contributions from and mesons 18,,, [nb/sr/mev] contribution, MeV (repulsive case) large tail but smooth elementary corss sections b/sr (Lab.) b/sr (Lab.) b/sr (Lab.) total 4 2 contribution, 15,2 MeV E contribution ex E [MeV], 3,1MeV Nagahiro et al., PRC (213)

13 decomposition into different final states Based on the coupled-channel cal. three final states (a) escape (b) (c) 3 [nb/sr/mev] 5.3fm 3.5 fm 4 1. fm 2 2 escape E ex E [MeV] E ex E [MeV] E ex E [MeV] 13

14 ( N) and (,N) reactions are also possible cf. 12 C,nreaction with =1.8 GeV/c 1.6 b/sr MeV] (p 3/2 ) 1 p a N =.5 fm V@ = ( i) MeV total (p 3/2 ) 1 d d 2 dde.6 (p 3/2 ) 1 s E ex E [MeV] 2 4 H. Nagahiro et al., PLB 14

15 Briefly about on-going theoretical works : We are now revisiting the scattering and -nucleus optical potential different model for vector-meson-baryon channel (K.P. Khemchandani, PRD84) trying to extract possible value scattering length, production, transparency ratio, & also -mesic nuclei formation, Sakamoto, Kiyomura (Nara WU) considering possibility to have bound state subtraction const. positive negative value (Λ~1GeV) (Oset-Ramos, PLB) (Hinata et al.) 3 Calculations by A. Hinata (w/o VB channels) N*(1535) [GeV] [GeV] 15

16 Summary : (958)-meson-nucleus bound system Partial restoration of Chiral sym and U A (1) anomaly effect in the viewpoint of mesic-nuclei (possible) large mass reduction without large absorption special feature of attraction from contact interaction smaller inelastic channel possibilities to observe bound state peaks ongoing theoretical works in NaraWU estimate possible (strength of singlet meson-baryon int.) transparency ratio of cross section scattering length and so on 16