Discovery of deeply bound π− states in the208Pb(d,3He) reaction

Yamazaki, T.; Hayano, R. S.; Itahashi, K.; Oyama, K.; Gillitzer, A.; Gilg, H. Albert; Knülle, M.; Münch, M.; Kienle, Paul; Schott, W.; Geißel, H.; Iwasa, N.; Münzenberg, G.

doi:10.1007/bf02769687

Cited by 51 publications

(73 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This narrowness is due to the repulsive s-wave pion interaction which 'pushes' its wave function outside of the nucleus, thus suppressing the absorption width. Recently the 1s and 2p π − 'deeply bound' atomic states (DBAS), which are inaccessible via the atomic cascade process, have been observed at GSI [20] using the recoilless (d, 3 He) reaction on two Pb isotopes, confirming the theoretical prediction.…”

Section: B Self Consistent Optical Potentials In Chirally Inspired Msupporting

confidence: 53%

“…4) these observables cease to rise approximately linearly with the strength of Im V opt . The lesson gained from discovering π − DBAS [20] is that nuclear reactions with momentum transfer q below 50 MeV/c should suit best the production of K − DBAS. First, the suppressive effects of the nuclear absorption on low-q production cross section are weaker than for reactions with higher values of q [25] and second, the angular momentum transfer is then minimal: ∆l ∼ 0, thus ensuring selectivity.…”

Section: B Self Consistent Optical Potentials In Chirally Inspired Mmentioning

confidence: 99%

See 1 more Smart Citation

Phenomenology of K− atoms and other strange hadronic atoms

Gal¹

2001

Nuclear Physics A

View full text Add to dashboard Cite

Recent optical-potential studies of the phenomenology of K − atoms are reviewed. It is shown that the data can be fitted by a complex optical potential with either a relatively shallow attractive component (∼ −50 MeV at ρ 0 ), as suggested by a self consistent application of chirally motivated coupled-channels models, or a relatively deep attractive component (∼ −180 MeV at ρ 0 ) as suggested by a mean-field extrapolation of a phenomenological low-density expansion. Both classes of these optical potentials, due to their strongly absorptive component, predict similarly structured relatively narrow 'deeply bound' K − atomic states with widths saturating at about 2 MeV. Possible formation reactions are briefly discussed. The more speculative case for relatively narrow deeply bound K − nuclear states is briefly mentioned. Recent works on other strange hadronic atom systems, for the Σ − and Ξ − hyperons, are also discussed.

show abstract

Section: B Self Consistent Optical Potentials In Chirally Inspired Msupporting

confidence: 53%

Section: B Self Consistent Optical Potentials In Chirally Inspired Mmentioning

confidence: 99%

Phenomenology of K− atoms and other strange hadronic atoms

Gal¹

2001

Nuclear Physics A

View full text Add to dashboard Cite

show abstract

“…Some extra repulsion comes also from the empirical dispersive component of the two-nucleon absorption term. The renewed interest in pionic atoms is based partly on the experimental observation of 'deeply bound' pionic atom states in the (d, 3 He) reaction [2][3][4][5], the existence of which was predicted a decade earlier [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Elastic scattering of low energy pions by nuclei and the in-medium isovectorπNamplitude

et al. 2005

View full text Add to dashboard Cite

Measurements of elastic scattering of 21.5 MeV π ± by Si, Ca, Ni and Zr were made using a single arm magnetic spectrometer. Absolute calibration was made by parallel measurements of Coulomb scattering of muons. Parameters of a pion-nucleus optical potential were obtained from fits to all eight angular distributions put together. The 'anomalous' s-wave repulsion known from pionic atoms is clearly observed and could be removed by introducing a chiral-motivated density dependence of the isovector scattering amplitude, which also greatly improved the fits to the data. The empirical energy dependence of the isoscalar amplitude also improves the fits to the data but, contrary to what is found with pionic atoms, on its own is incapable of removing the anomaly.

show abstract

“…Our program aims at measuring the isovector πN interaction parameter in the pion-nucleus potential (b * 1 (ρ)) [15] by studying deeply bound 1s states of π − in heavy N > Z nuclei [16,17,18,19,20]. Such states were predicted to be produced as discrete states by nuclear reactions [21,22,23,24,25] and to provide unique information on the s-wave interaction, whereas in most pionic atoms the repulsive s-wave interaction is nearly counterbalanced by the attractive p-wave interaction (see, for instance, Batty et al [26]).…”

mentioning

confidence: 99%

“…Since the 1s binding energy is insensitive to the p-wave potential, we could safely fix the p-wave parameters to the known values from pionic atom data [26]. Hereafter, the units of m Sn, 28 Si, 20 Ne, 16 The smallness of ReB 0 (−0.019 ± 0.017) supports the value (−0.038±0.025) claimed from the requirement that the effective b 0 consists of the free πN value and the double-scattering term [28]. The combined isoscalar parameter, b 0 + 0.215 ReB 0 = −0.0274 ± 0.0002, is in good agreement with that obtained in the analysis of the 205 Pb [28].…”

mentioning

confidence: 99%

Precision Spectroscopy of Pionic1sStates of Sn Nuclei and Evidence for Partial Restoration of Chiral Symmetry in the Nuclear Medium

et al. 2004

Self Cite

View full text Add to dashboard Cite

Deeply bound 1s states of π − in 115,119,123 Sn were preferentially observed using the Sn(d, 3 He) pion-transfer reaction under the recoil-free condition. The 1s binding energies and widths were precisely determined, and were used to deduce the isovector parameter of the s-wave pion-nucleus potential to be b1 = −0.115 ± 0.007 m −1 π . The observed enhancement of |b1| over the free πN value (b free 1 /b1 = 0.78 ± 0.05) indicates a reduction of the chiral order parameter, f * π (ρ) 2 /f 2 π ≈ 0.64, at the normal nuclear density, ρ = ρ0.PACS numbers: 36.10. Gv,13.75.Gx,14.40.Aq,25.45.Hi Our work deals with characteristic properties of strongly interacting bound sytems, hadrons, consisting of light quarks (u and d). Their masses are nearly two orders of magnitude smaller (m u ≃ 5MeV, m d ≃ 8MeV) than typical hadron masses of ≈ 1 GeV. This extraordinary phenomenon is proposed to be produced by spontaneous breaking of chiral symmetry for massless quarks subject to the strong interaction [1,2,3]. It results in a ground state, the vacuum state, with a finite expectation value of quark-antiquark pairs, qq 0 ≈ −(250 MeV) 3 [4]. In such a scenario the hadrons are considered as quasi particle excitations of the condensate, qq , separated by an energy gap of ∼ 1 GeV. The lowest energy excitation modes of the condensate, so called Nambu-Goldstone bosons, are identified as pions. Their s-wave interaction with nucleons is predicted to vanish in its isoscalar part, and determined by the pion decay constant, f 2 π , in its isovector part [5,6] which is consistent with recent experimental values [7,8]. The f 2 π is also the order parameter of chiral symmetry breaking and directly connected to the magnitude of qq through the Gell-Mann-OaksRenner relation [4].We examine this chiral symmetry scenario by implanting a π − in a nuclear medium of density ρ [9, 10], where a new vacuum state with a reduced condensate, qq ρ , is proposed to be created [2]. This is the most basic case of a large effort to study the density and temperature dependence of the qq in relativistic heavy ion collisions.The density dependence of the quark condensate is expressed in the leading order by the pion-nucleon σ-term (σ N ≈ 45 MeV) in the following form [11]:which yields a reduction of about 0.65 for the normal nuclear density, ρ = ρ 0 = 0.17 fm −3 . Likewise, the pion decay constant in a medium (identified as the time component of the axial current) is reduced as [12],where the parameter α is predicted to be αρ 0 ≈ 0.45 from the chiral dynamics [13]. This reduction of the ratio is associated with the free and the in-medium isovector πN scattering length (b free 1 and b * 1 , respectively) as [14]Our program aims at measuring the isovector πN interaction parameter in the pion-nucleus potential (b * 1 (ρ)) [15] by studying deeply bound 1s states of π − in heavy N > Z nuclei [16,17,18,19,20]. Such states were predicted to be produced as discrete states by nuclear reactions [21,22,23,24,25] and to provide unique information on the s-wave interaction, where...

show abstract

Discovery of deeply bound π− states in the208Pb(d,3He) reaction

Cited by 51 publications

References 7 publications

Phenomenology of K− atoms and other strange hadronic atoms

Phenomenology of K− atoms and other strange hadronic atoms

Elastic scattering of low energy pions by nuclei and the in-medium isovectorπNamplitude

Precision Spectroscopy of Pionic1sStates of Sn Nuclei and Evidence for Partial Restoration of Chiral Symmetry in the Nuclear Medium

Contact Info

Product

Resources

About